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Why India is becoming a preferable place for foreign companies to run a pharma franchise?

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Aug 092014
 

Why India is becoming a preferable place for foreign companies to run a pharma franchise?

Various pharma companies in abroad are looking for partners in India for their pharma franchise business. There are many reasons that influence them to show interest in India based pharma franchise industry. We all are aware of the fact that India is a place where one can easily get cheap labor and innovation. The great minds working for technology development come up with latest equipments and machineries based of better technology for production of pharma products.

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http://pharma-marketing-india.blogspot.in/2014/08/why-india-is-becoming-preferable-place.html

 

 

 

 

 

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Cefuroxime Axetil

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Aug 092014
 

Figure 1 :Chemical structure of Cefuroxime Axetil

Cefuroxime Axetil

[6R- [6alpha, 7beta (Z)]] – 3 – [[(Aminocarbonyl) oxy] methyl] -7 – [[2-furanyl (methoxyimino) acetyl] amino] -8-oxo-5-thia-1- azabicyclo [4.2.0] oct-2-ene-2-carboxylic acid 1- (acetyloxy) ethyl ester
64544-07-6, 55268-75-2 (free acid), 56238-63-2 (Na salt)
Ceftin; Zinnat; Elobact; Zinat; Cefuroxime 1-acetoxyethyl ester; Bioracef; CXM-AX; Coliofossim; Celocid
Molecular Formula: C20H22N4O10S   Molecular Weight: 510.47448

Cefuroxime Axetil (1-(acetyloxy) ethyl ester of cefuroxime, is (RS)-1-hydroxyethyl (6R,7R)-7-[2-(2-furyl)glyoxyl-amido]-3-(hydroxymethyl)-8-oxo-5-thia-1-azabicyclo[4.2.0]-oct-2-ene-2-carboxylate, 7 2 -(Z)-(O-methyl-oxime), 1-acetate 3-carbamate.

Its molecular formula is C 20 H 22 N 4 O 10S, and it has a molecular weight of 510.48.

Cefuroxime Axetil is used orally for the treatment of patients with mild-to-moderate infections, caused by susceptible strains of the designated microorganisms.

 

Cefuroxime axetil is a second generation oral cephalosporin antibiotic. It was discovered by Glaxo now GlaxoSmithKline and introduced in 1987 as Zinnat.[1] It was approved by FDA on Dec 28, 1987.[2] It is available by GSK as Ceftin in US[3] and Ceftum in India.[4]

It is an acetoxyethyl ester prodrug of cefuroxime which is effective orally.[5] The activity depends on in vivo hydrolysis and release of cefuroxime.

Cefuroxime is chemically (6R, 7R)-3-carbamoyloxymethyl-7-[(Z)-2-(fur-2-yl)-2-methoxy-iminoacetamido] ceph-3-em-4-carboxylic acid and has the structural Formula II:

Figure US06833452-20041221-C00001

 

Cefuroxime axetil having the structural Formula I:

Figure US06833452-20041221-C00002

 

is the 1-acetoxyethyl ester of cefuroxime, a cephalosporin antibiotic with a broad spectrum of activity against gram-positive and gram negative micro-organisms.

This compound as well as many other esters of cefuroxime, are disclosed and claimed in U.S. Pat. No. 4,267,320. According to this patent, the presence of an appropriate esterifying group, such as the 1-acetoxyethyl group of cefuroxime axetil, enhances absorption of cefuroxime from the gastrointestinal tract, whereupon the esterifying group is hydrolyzed by enzymes present in the human body.

Because of the presence of an asymmetric carbon atom at the 1-position of the 1-acetoxyethyl group, cefuroxime axetil can be produced as R and S diastereoisomers or as a racemic mixture of the R and S diastereoisomers. U.S. Pat. No. 4,267,320 discloses conventional methods for preparing a mixture of the R and S isomers in the crystalline form, as well as for separating the individual R and S diastereoisomers.

The difference in the activity of different polymorphic forms of a given drug has drawn the attention of many workers in recent years to undertake the study on polymorphism. Cefuroxime axetil is the classical example of amorphous form exhibiting higher bioavailability than the crystalline form.

U.S. Pat. No. 4,562,181 and the related U.S. Pat. Nos. 4,820,833; 4,994,567 and 5,013,833, disclose that cefuroxime axetil in amorphous form, essentially free from crystalline material and having a purity of at least 95% aside from residual solvents, has a higher bioavailability than the crystalline form while also having adequate chemical stability.

These patents disclose that highly pure cefuroxime axetil can be recovered in substantially amorphous form from a solution containing cefuroxime axetil by spray drying, roller drying, or solvent precipitation. In each case, crystalline cefuroxime axetil is dissolved in an organic solvent and the cefuroxime axetil is recovered from the solution in a highly pure, substantially amorphous form.

Another U.S. Pat. No. 5,063,224 discloses that crystalline R-cefuroxime axetil which is substantially free of S-isomer is readily absorbed from the stomach and gastrointestinal tract of animals and is therefore ideally suited to oral therapy of bacterial infections.

According to this patent, such selective administration of R-cefuroxime axetil results in surprisingly greater bioavailability ability of cefuroxime, and thus dramatically reduces the amount of unabsorbable cefuroxime remaining in the gut lumen, thereby diminishing adverse side effects attributable to cefuroxime.

British Patent Specification No. 2,145,409 discloses a process for obtaining pure crystalline cefuroxime axetil and is said to be an improvement over British Patent Specification No. 1,571,683. Sodium cefuroxime is used as the starting material in the disclosed specification, which in turn, is prepared from either 3-hydroxy cefuroxime or cefuroxime.

Said process involves an additional step of preparing sodium cefuroxime, and therefore is not economical from commercial point of view.

 

 

CEFTIN (cefuroxime axetil) Tablets and CEFTIN (cefuroxime axetil) for Oral Suspension contain cefuroxime as cefuroxime axetil. CEFTIN (cefuroxime axetil) is a semisynthetic, broad-spectrum cephalosporin antibiotic for oral administration.

Chemically, cefuroxime axetil, the 1-(acetyloxy) ethyl ester of cefuroxime, is (RS)-1-hydroxyethyl (6R,7R)-7-[2-(2-furyl)glyoxyl-amido]-3-(hydroxymethyl)-8-oxo-5-thia-1-azabicyclo[4.2.0]-oct-2-ene-2-carboxylate, 72-(Z)-(O-methyl-oxime), 1-acetate 3-carbamate. Its molecular formula is C20H22N4O10S, and it has a molecular weight of 510.48.

Cefuroxime axetil is in the amorphous form and has the following structural formula:

 

CEFTIN (cefuroxime axetil tablets) Structural Formula Illustration

 

CEFTIN (cefuroxime axetil) Tablets are film-coated and contain the equivalent of 250 or 500 mg of cefuroxime as cefuroxime axetil. CEFTIN (cefuroxime axetil) Tablets contain the inactive ingredients colloidal silicon dioxide, croscarmellose sodium, hydrogenated vegetable oil, hypromellose, methylparaben, microcrystalline cellulose, propylene glycol, propylparaben, sodium benzoate, sodium lauryl sulfate, and titanium dioxide.

CEFTIN (cefuroxime axetil) for Oral Suspension, when reconstituted with water, provides the equivalent of 125 mg or 250 mg of cefuroxime (as cefuroxime axetil) per 5 mL of suspension. CEFTIN (cefuroxime axetil) for Oral Suspension contains the inactive ingredients acesulfame potassium, aspartame, povidone K30, stearic acid, sucrose, tutti-frutti flavoring, and xanthan gum.

 

Cefuroxime axetil
Cefuroxime axetil.svg
Systematic (IUPAC) name
1-Acetoxyethyl (6R,7R)-3-[(carbamoyloxy)methyl]-7-{[(2Z)-2-(2-furyl)-2-(methoxyimino)acetyl]amino}-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate
Clinical data
 
Identifiers
 
PubChem CID 6321416
ChemSpider 4882027
ChEMBL CHEMBL1095930
Synonyms Cefuroxime 1-acetoxyethyl ester
Chemical data
Formula C20H22N4O10S 
Mol. mass 510.475 g/mol

Table 2 :FT-IR peaks of pure Cefuroxime Axetil, urea, and physical mixture of Cefuroxime Axetil and urea

dsc

Figure 2 :Differential scanning calorimetry of Cefuroxime Axetil

 

http://www.google.com/patents/US5013833

 

Chemical structure for cefuroxime axetil

http://www.google.com/patents/US6833452

EXAMPLE 1

Dicyclohexylamine (17.2 g) in N,N-dimethylacetamide (50 ml) was added to a solution of cefuroxime acid (42.4 g) in N,N-dimethylacetamide (300 ml) at about −10° C. (R,S)1-Acetoxethylbromide (33.4 g) in N,N-dimethylacetamide (50 ml) was added to the above solution and the reaction mixture was stirred for 45 minutes at about −3 to 0° C. Potassium carbonate (1.1 g) was added to the reaction mixture and it was further stirred at that temperature for about 4 hours. The reaction mixture was worked up by pouring into it ethyl acetate (1.0 It), water (1.2 It) and dilute hydrochloric acid (3.5% w/w, 200 ml). The organic layer was separated and the aqueous layer was again extracted with ethyl acetate. The combined organic extracts were washed with water, dilute sodium bicarbonate solution (1%), sodium chloride solution and evaporated in vacuo to give a residue. Methanol was added to the residue and the crude product was precipitated by adding water.

The resulting precipitate was filtered off and recrystallized from the mixture of ethylacetate, methanol and hexane. The precipitated product was filtered, washed and dried to give pure crystalline cefuroxime axetil (42.5 g).

Assay (by HPLC on anhydrous basis)-98.2% w/w; Diastereoisomer ratio-0.53; Total related substances-0.48% w/w.

…………………………………

http://www.google.com/patents/EP1409492B1?cl=en

    • The present invention relates to an improved method for synthesis of cefuroxime axetil of formula (I) in high purity substantially free of the corresponding 2-cephem(Δ2)-ester of formule (II) and other impurities. The compound produced is valuable as a prodrug ester of the corresponding cephalosporin- 4-carboxylic acid derivative i. e. cefuroxime, particularly suitable for oral administration in various animal species and in man for treatment of infections caused by gram-positive and gram-negative bacteria.
Figure imgb0001
Figure imgb0002

BACKGROUND OF THE INVENTION

  • [0002]
    One of the ways to improve the absorption of cephalosporin antibiotics which are poorly absorbed through the digestive tract is to prepare and administer the corresponding ester derivatives at the 4-carboxylic acid position. The esters are then readily and completely hydrolysed in vivoby enzymes present in the body to regenerate the active cephalosporin derivative having the free carboxylic acid at the 4-position.
  • [0003]
    Among the various ester groups that can be prepared and administered only a selected few are biologically acceptable, in addition to possessing high antibacterial activity and broad antibacterial spectrum. Clinical studies on many such potential “prodrug esters” such as cefcanel daloxate (Kyoto), cefdaloxime pentexil tosilate (Hoechst Marion Roussel) and ceftrazonal bopentil (Roche), to name a few have been discontinued, while ceftizoxime alapivoxil ((Kyoto) in under Phase III clinical studies. The cephalosporin prodrug esters which have been successfully commercialised and marketed include cefcapene pivoxil (Flomox® , Shionogi), cefditoren pivoxil (Spectracef®, Meiji Seika), cefetamet pivoxil (Globocef®, Roche), cefotiam hexetil (Taketiam®, Takeda), cefpodoxime proxetil (Vantin®, Sankyo), cefteram pivoxil (Tomiron®, Toyama) and cefuroxime axetil (Ceftin® and Zinnat®, Glaxo Wellcome).
  • [0004]
    Typically, such (3,7)-substituted-3-cephem-4-carboxylic acid esters represented by formula (I A) are synthesised by reacting the corresponding (3,7)-substituted-3- cephem-4-carboxylic acid derivative of formula (III A), with the desired haloester compound of formula (IV A) in a suitable organic solvent. The synthesis is summarised in Scheme-I, wherein in compounds of formula (I A), (II A), (III A) and (IV A) the groups R1 and R2 at the 3- and 7-positions of the β-lactam ring are substituents useful in cephalosporin chemistry ; R3 is the addendum which forms the ester function and X is halogen.
Figure imgb0003
  • [0005]
    However, the esterification reaction which essentially involves conversion of a polar acid or salt derivative to a neutral ester product invariably produces the corresponding (3,7)-substituted-2-cephem (Δ2)-4-carboxylic acid ester derivative of formula (II A) in varying amounts, arising out of isomerisation of the double bond from the 3-4 position to the 2-3 position as well as other unidentified impurities.
  • [0006]
    It has been suggested [D. H. Bentley, et. al., Tetrahedron Lett., 1976, 41, 3739] that the isomerisation results from the ability of the 4-carboxylate anion of the starting carboxylic acid to abstract a proton from the 2-position of the 3-cephem-4-carboxylic acid ester formed, followed by reprotonation at 4-position to give the said Δ2-ester. It has also been suggested [R. B. Morin, et. al., J. Am. Chem. Soc., 1969, 91, 1401 ; R. B. Woodward, et. al., J. Am. Chem. Soc., 1966, 88, 852] that the equilibrium position for isomerisation is largely determined by the size of the ester addendum attached at the 4-carboxylic acid position.
  • [0007]
    The 2-cephem-4-carboxylic acid esters of formula (II A) are not only unreactive as antibacterial agents but are undesired by-products. Pharmacopoeias of many countries are very stringent about the presence of the 2-cephem analogues in the finished sample of (3,7)-substituted-3-cephem-4-carboxylic acid esters and set limits for the permissible amounts of these isomers. Due to the structural similarity of the 2-cephem and 3-cephem analogues it is very difficult to separate the two isomers by conventional methods, such as chromatography as well as by fractional crystallisation. In addition to this removal of other unidentified impurities formed in the reaction, entails utilisation of tedious purification methods, thus overall resulting in,

    1. a) considerable loss in yield, increasing the cost of manufacture and
    2. b) a product of quality not conforming to and not easily amenable for upgradation to pharmacopoeial standards.
  • [0008]
    Several methods are reported in the prior art for synthesis of cefuroxime axetil of formula (I) and various (3,7)-substituted-3-cephem-4-carboxylic acid esters of formula (I A), with attempts to minimise the unwanted Δ2-isomers formed in such reactions as well as conversion of the Δ2-isomer thus formed back to the desired Δ3– isomer. The prior art methods can be summarised as follows:

    • i) US Patent No, 4 267 320 (Gregson et. al.) describes a method for synthesis of cefuroxime axetil comprising reaction of cefuroxime acid or its alkali metal salts or onium salts with (R,S)-1-acetoxyethyl bromide in an inert organic solvent selected from N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, acetone, acetonitrile and hexamethylphosphoric triamide at a temperature in the range of -50 to +1150° C. The patent mentions that when alkali metal salts, specially potassium salt of cefuroxime acid are employed the reaction can be carried out in a nitrile solvent in the presence of a crown ether. When cefuroxime acid is employed the reaction is carried out in the presence of a weak inorganic base such as sodium carbonate or potassium carbonate, which is added prior to the addition of the haloester. The patent further mentions that the use of potassium carbonate in conjunction with the haloester, specially the bromo or iodo ester is preferred since it helps to minimise the formation of the Δ2-isomer. Ideally, substantially equivalent amounts of cefuroxime acid and the base is employed.
      The US Patent No. 4 267 320 also describes methods, wherein the said esterification is carried out in the presence of an acid binding agent, which serve to bind hydrogen halide liberated in the reaction, thereby controlling the formation of the Δ2-isomer. The acid binding agents that are utilised include a tertiary amine base such as triethylamine or N, N-dimethylamine ; an inorganic base such as calcium carbonate or sodium bicarbonate and an oxirane compound such as ethylene oxide or propylene oxide.
      However, from the examples provided in the above patent the yield of cefuroxime axetil and other (3,7)-substituted-3-cephem-4-carboxylic acid esters obtained is found to be only of about 50%, implying formation of substantial amounts of impurities in the reaction. Indeed, when cefuroxime acid is reacted with (R,S)-1-acetoxyethyl bromide in the presence of 0.55 molar equivalents of sodium carbonate or potassium carbonate in N,N-dimethylacetamide as solvent, as per the process disclosed in this patent, it is found that substantial amounts of the Δ2-isomer in a proportion ranging from 10-22% is formed, in addition to other unknown impurities. Also, substantial amounts of the starting cefuroxime acid remains unreacted even after 5 hrs of reaction. Isolation of the product generally affords a gummy material, which resists purification even after repeated crystallisations.
      Moreover, the use of the acid binding agents mentioned in the above patent, specially tertiary amines and inorganic bases lead to cleavage of the β-lactam ring and also promote the undesired Δ2-isomerisation, thereby enhancing the level of impurities formed in the reaction.
    • ii) GB Patent No. 2 218 094 describes a method by which the Δ2-isomers formed during esterification can be converted back to the desired Δ3-isomers. The method comprises of oxidation of the dihydrothiazine ring in the mixture of Δ2– and Δ3– cephalosporin acid esters to the corresponding sulfoxide derivatives with suitable oxidising agents, whereby the Δ2-isomer gets isomerised to the corresponding Δ3-isomer during oxidation and the Δ3– cephalosporin acid ester sulfoxide is isolated. The sulfide group is regenerated back by reduction of the sulfoxide function with suitable reducing agents.
      Typically, the oxidation is carried out using m-chloroperbenzoic acid and the reduction achieved by use of an alkali metal halide in presence of acetyl chloride in presence of an inert organic solvent or by use of a phosphorous trihalide.
      Although, this method provides the desired Δ3-isomers in good purity, it cannot be considered as an industrially feasible method since it involves a two step process of oxidation and reduction, isolation of the intermediate products at each stage and necessary purifications, all resulting in considerable loss of the desired product and increase in the cost of manufacture. Moreover, the use of acetyl halide and phosphorous trihalide in the reduction step cannot be applied to cephalosporin derivatives that are sensitive to these reagents.
      A similar method has been reported by Kaiser et. al. in J. Org. Chem., 1970, 35, 2430.
    • (iii)Mobasherry et. al. in J. Org. Chem., 1986, 51, 4723 describe preparation of certain Δ3-cephalosporin-4-carboxylic acid esters by reaction of the corresponding 3-cephem-4-carboxylic acids (in turn prepared form the corresponding carboxylic acid alkali metal salts) with an haloester in presence of 1.1 eq of sodium carbonate in the presence 1.2-1.5 eq of an alkyl halide and in presence of a solvent comprising of a mixture of N,N-dimethylformamide and dioxane. The authors claim that the method provides of Δ3– cephalosporin-4-carboxylic acid esters unaccompanied by the corresponding Δ2-isomer.
      However, the method involves an additional step in that the starting 3-cephem-4-carboxylic acid ester derivatives are obtained from the corresponding alkali metal salts prior to reaction. In addition, longer reaction times of about 24 hrs coupled with the fact that it utilises dioxane, a potent carcinogen, not recommended by International Conference on Harmonisation (ICH) on industrial scale renders the method unattractive commercially.
      Moreover, on duplication of the method exactly as described in the article it is found that about 3-4% of the corresponding Δ2-isomer is indeed formed in the reaction in addition to other unidentified impurities. Also, substantial amounts of the starting cephalosporin carboxylic acid is recovered unreacted.
    • (iv)Shigeto et. al. in Chem. Pharm. Bull., 1995, 43(11), 1998 have carried out the esterification of certain 7-substituted-3-cephem-4-carboxylic acid derivatives with 1-iodoethyl isopropyl carbonate in a solvent system containing a mixture of N, N-dimethylformamide and dioxane in a 3:5 ratio. A conversion to the corresponding 3-cephem- 4-carboxylate ester was achieved in only 34%, out of which the Δ2-isomer amounted to about 8%.
      Esterification of 7-formamido-3-(N,N-dimethylcarbamoyloxy)methyl-3-cephem-4-carboxylic acid sodium salt with a suitable haloester in presence of solvents such as N, N-dimethylacetamide and N, N-dimethylformamide, with formation of about 0.8 to 3.0% of the Δ2-isomer is also reported in the above article by Shigeto et. al. The 7-formamido group was cleaved under acidic conditions to give the corresponding 7-amino derivative contaminated with only about 0.4% of the corresponding Δ2-isomer. The minimisation of the percentage of Δ2-isomer is attributed to the relative unstability of 7-amino-2-cephem-4-carboxylic acid esters in acidic conditions, facilitating isomerisation of the 2-cephem intermediate to the 3-cephem derivative.
      However, the method does not have a general application, especially for synthesis of commercially valuable cephalosporin derivatives containing hydroxyimino or alkoxyimino substituents in the 7-amino side chain addendum, since these oxyimino functions exhibit a tendency to isomerise from the stable (Z)-configuration to the relatively undesirable(E)-configuration under acidic conditions. This would render separation of the two isomers cumbersome. Moreover, longer reaction times of about 18-20 hrs to effect the isomerisation of the double bond from the 2- position to the 3-position and use of toxic dioxane as solvent impose further limitations on the method.
      (v) Demuth et. al. in J. Antibiotics, 1991, 44, 200 have utilised the N, N-dimethylformamide-dioxane system in the coupling of 1-iodocephem-4-nitrobenzyl ester with naldixic acid sodium salt and recommend use of dioxane since it reduces the basicity of the quinolone carboxylate and lowers the polarity of the reaction medium.
      However, low yields of about 35% and use of toxic dioxane makes the method of little industrial application.
    • (vi) Wang et. al. in US Patent No. 5 498 787 claim a method for preparation of certain (3,7)-substituted-3-cephem-4-carboxylic acid prodrug esters, unaccompanied by the analogous 2-cephem esters comprising reaction of the corresponding (3,7)-substituted-3-cephem-4-carboxylic acid alkali metal salts with suitable haloesters in the presence of catalytic amounts of a quaternary ammonium or quarternary phosphonium salt. Among the prodrug esters covered in this patent is cefuroxime axetil.
      US Patent No. 5 498 787 claims that among the quarternary ammonium salts, such salts with acid counter ion, specially tetrabutyl ammonium sulfate (TBA+HSO4 –) is the most preferred. When the molar ratio of TBA+HSO4 –/cefuroxime sodium was above 0.40 no Δ2-isomer was detected, when the said molar ratio was below 0.40 and near about 0.20 the molar ratio of Δ2/Δ3 isomers formed was about 2.0%. When no TBA+HSO4 – was added the molar ratio of Δ2/Δ3 isomers formed was about 10.0%. Examples 1 and 2 of this patent illustrate the esterification of cefuroxime sodium in presence of TBA+HSO4 – and indicate that the Δ2-isomer was not detected after 3-12 hours of reaction. The same patent also establishes the superiority of TBA+HSO4 – over other salts, specially tetrabutyl ammonium iodide (TBA+I–) since use of the latter salt resulted in considerable isomerisation of the double bond giving the undesired Δ2-isomer in predominant amounts.
      The present inventors have, however, found that when cefuroxime sodium is reacted with (R,S)- 1-acetoxyethyl bromide in the presence of tetrabutylammonium sulfate (TBA+HSO4 –) as per the method covered in US Patent No. 5,498 787 the same did not necessarily result in the production of the desired Δ3isomer free of the undesired Δ2 isomer and other impurities. Also, such process had limitations in that the reaction could not be completed at times even at the end of 5.0hrs. Moreover, the separation of the impurities; from the product proved cumbersome and could not be removed from the product even after successive crystallisations.
    • (vii) H. W. Lee et. al., Syntheic Communications, 1998, 28(23), 4345-4354 have demonstrated a method essentially similar to that claimed in US Patent No. 5 498 787 . The method of preparation of various esters of cefotaxime consists of reacting cefotaxime sodium with the requisite haloester compound in a suitable solvent and in presence of quarternary ammonium salts as phase transfer catalysts. It is claimed that when no quarternary ammonium salts are added the molar ratio (%) of Δ2/Δ3 isomers formed is about 10%. The formation of Δ2– isomer is minimised when quarternary ammonium salts are added and particularly when the molar ratio of TBA+HSO4 –/cefotaxime sodium employed is 0.80 the formation of the Δ2– isomer is completely inhibited.
      However, this method requires long hours (~18-24 hrs) and is carried out at higher temperatures (40-45° C) and as such may not be suitable for cephalosporin derivatives that are sensitive to heat.
    • (viii)H. W. Lee et. al. in Synthetic Communications, 1999, 29(11), 1873-1887 demonstrate a method for preparation of number of (3,7)-substituted-3-cephem-4-carboxylic acid esters comprising reacting the corresponding (3,7)-substituted-3-cephem-4-carboxylic acid derivatives with a base selected form cesium carbonate or cesium bicarbonate either used alone or in combination with potassium carbonate, sodium carbonate, potassium bicarbonate and sodium bicarbonate. The authors established that the formation of Δ2– isomers could be minimised by utilisation of a solvent combination ofN, N-dimethyl formamide and dioxane. The use of the latter mentioned solvent i. e. dioxane was expected to lower polarity of the reaction medium and thereby reduce the basicity of the transient 3-cephem-4-carboxylate anion formed in the reaction and thus preventing the isomerisation of the double bond from the 3-4 position to the 2-3 position.
      The formation of the Δ2– isomer was found to be dependent on the amount of dioxane in the solvent mixture, the more the proportion of dioxane lesser the degree of isomerisation.
      However, yields of representative esters obtained by the method are in the range of 45-85 %, implying that the reaction is accompanied by formation of substantial amounts of impurities and that the isomerisation is dependent on the nature of the substituent at 3α-position of the cephalosporin nucleus as well as on the nature of the haloester employed. Moreover, the method utilises dioxane, not desirable for reasons mentioned herein earlier and expensive cesium salts. This method, therefore, also has limited application.
    • (ix) Y.S. Cho et. al., in Korean J. Med. Chem., 1995, 5(1), 60-63 describe synthesis of several cephalosporin prodrug esters and their efficacy on oral administration. The esters were synthesised by reacting the corresponding cephalosporin-4-carboxylic acid derivative with the respective haloester derivative in presence of cesium carbonate and N, N-dimethylacetamide. The yields of the ester derivatives obtained are in the range of only 25-56%, indicating formation of substantial amounts of impurities in the reaction.

Example – 1

      Preparation of (R, S -1-Acetoxyethyl-3-carbamoyloxymethyl-7-[(Z)-2-(fur-2-yl)-2-methoxyiminoacetamido]ceph-3-em-4-carboxylate (Cefuroxime axetil, I) :

Without use of GrouplI

      /

II metal phosphate and C1-4 alcohol

  • [0045]
    (R, S)-1-Acetoxyethyl bromide (1.6gms; 0.0094moles) was added to a mixture of cefuroxime acid (2gms; 0.0047moles) and potassium carbonate (0.326gms; 0.00235moles) in N,N-dimethylacetamide (10 ml) at 5°C and stirred at 0 to 20° C for 180 minutes Ethyl acetate was added to the reaction mixture, followed by 3% aqueous sodium bicarbonate solution (15ml). The organic layer containing the title product, Δ2 isomer (8.51%) and unidentified impurities (X1-1.86% and X2 – 3.54%) was separated and washed with 10% aqueous NaCl solution. The organic solvent was evaporated off under vacuum to give 1.08gms (44.90%) of the title compound as a gummy solid.
  • [0046]
    HPLC analysis : Purity (compound I) – 89.11% ; Impurities : Δ2 isomer (II) – 8.51%, X1 – 1.86% and X2 – 3.54%

 

………………………………..

The reaction of 3-hydroxymethyl-7- [2- (2-furyl) -2-methoxyiminoacetamido] -3-cephem-4-carboxylic acid (I) with chlorosulfonyl isocyanate (II) and then with sodium 2-ethylhexanoate gives sodium cefuroxime (III), which is then treated with 1-bromoethyl acetate (IV) in DMA.

 

 

References

  1.  “Our history – About GSK”. GlaxoSmithKline.
  2.  http://www.drugs.com/monograph/cefuroxime-axetil.html
  3.  https://www.gsksource.com/gskprm/en/US/adirect/gskprm?cmd=ProductsByName#C
  4.  “Our products”. GlaxoSmithKline.
  5.  Walter Sneader. Drug Discovery: A History. John Wiley, Chichester, UK. ISBN 0-471-89979-8.

 

5-18-2005
Intermediates in cephalosporin production
12-22-2004
Process for the preparation of highly pure crystalline (R,S)-cefuroxime axetil

 

Citing Patent Filing date Publication date Applicant Title
US5847118 * Jul 25, 1997 Dec 8, 1998 Apotex, Inc. Methods for the manufacture of amorphous cefuroxime axetil
US6060599 * Jun 17, 1998 May 9, 2000 Ranbaxy Laboratories Limited Process for the preparation of cefuroxime axetil in an amorphous form
US6107290 * Sep 16, 1999 Aug 22, 2000 Hammi Pharm Co., Ltd. Non-crystalline cefuroxime axetil solid dispersant, process for preparing same and composition for oral administration thereof
US6323193 Aug 21, 2000 Nov 27, 2001 Ranbaxy Laboratories Limited Bioavailable oral dosage form of cefuroxime axetil
US6384213 May 19, 2000 May 7, 2002 Ranbaxy Laboratories Limited Process for preparing a pure, pharmacopoeial grade amorphous form of cefuroxime axetil
US6534494 Jan 27, 1999 Mar 18, 2003 Ranbaxy Laboratories Limited Process for the preparation of cefuroxime axetil in an amorphous form
US6833452 Jul 16, 2001 Dec 21, 2004 Ranbaxy Laboratories Limited Process for the preparation of highly pure crystalline (R,S)—cefuroxime axetil
US6911441 * Dec 16, 2002 Jun 28, 2005 Akzo Nobel N.V. Prolonged release pharmaceutical composition
US7507813 Jul 22, 2005 Mar 24, 2009 Nanomaterials Technology Pte Ltd. Amorphous cefuroxime axetil and preparation process therefore
CN1909889B Jan 10, 2005 Jun 2, 2010 韩美药品株式会社 Cefuroxime axetil granule and process for the preparation thereof
EP1619198A1 * Jul 14, 2005 Jan 25, 2006 Nanomaterials Technology Pte Ltd Amorphous cefuroxime axetil and preparation process therefore
WO1999065919A1 * Jan 27, 1999 Dec 23, 1999 Ranbaxy Lab Ltd Process for the preparation of cefuroxime axetil in an amorphous form
WO2001010410A1 * Jul 25, 2000 Feb 15, 2001 Hanmi Pharm Ind Co Ltd Non-crystalline cefuroxime axetil solid dispersant, process for preparing same and composition for oral administration thereof
WO2003014126A1 * Aug 1, 2002 Feb 20, 2003 Marco Alpegiani Process for the preparation of highly pure cefuroxime axetil
WO2005065658A1 * Jan 10, 2005 Jul 21, 2005 Hee Chul Chang Cefuroxime axetil granule and process for the preparation thereof
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Key steps in implementation of QbD for a biotech product…….Quality by design for biopharmaceuticals

 regulatory  Comments Off on Key steps in implementation of QbD for a biotech product…….Quality by design for biopharmaceuticals
Aug 052014
 

Unfortunately we are unable to provide accessible alternative text for this. If you require assistance to access this image, or to obtain a text description, please contact npg@nature.com

 

 

Identifying target product profile (TPP). TPP has been defined as a “prospective and dynamic summary of the quality characteristics of a drug product that ideally will be achieved to ensure that the desired quality, and thus the safety and efficacy, of a drug product is realized”. This includes dosage form and route of administration, dosage form strength(s), therapeutic moiety release or delivery and pharmacokinetic characteristics (e.g., dissolution and aerodynamic performance) appropriate to the drug product dosage form being developed and drug product-quality criteria (e.g., sterility and purity) appropriate for the intended marketed product. The concept of TPP in this form and its application is novel in the QbD paradigm.

Identifying CQAs. Once TPP has been identified, the next step is to identify the relevant CQAs. A CQA has been defined as “a physical, chemical, biological, or microbiological property or characteristic that should be within an appropriate limit, range, or distribution to ensure the desired product quality”10. Identification of CQAs is done through risk assessment as per the ICH guidance Q9 . Prior product knowledge, such as the accumulated laboratory, nonclinical and clinical experience with a specific product-quality attribute, is key in making these risk assessments. Such knowledge may also include relevant data from similar molecules and data from literature references. Taken together, this information provides a rationale for relating the CQA to product safety and efficacy. The outcome of the risk assessment would be a list of CQAs ranked in order of importance. Use of robust risk assessment methods for identification of CQAs is novel to the QbD paradigm.

Defining product design space. After CQAs for a product have been identified, the next step is to define the product design space (that is, specifications for in-process, drug substance and drug product attributes). These specifications are established based on several sources of information that link the attributes to the safety and efficacy of the product, including, but not limited to, the following:

  • Clinical design space
  • Nonclinical studies with the product, such as binding assays, in vivo assays and in vitro cell-based assays
  • Clinical and nonclinical studies with similar platform products
  • Published literature on other similar products
  • Process capability with respect to the variability observed in the manufactured lots

The difference between the actual experience in the clinic and the specifications set for the product would depend on our level of understanding of the impact that the CQA under consideration can have on the safety and efficacy of the product. For example, taking host cell proteins as a CQA, it is common to propose a specification that is considerably broader than the clinical experience. This is possible because of a greater ability to use data from other platform molecules to justify the broader specifications. On the other hand, in the case of an impurity that is unique to the product, the specifications would rely solely on clinical and nonclinical studies.

In QbD, an improved understanding of the linkages between the CQA and safety and efficacy of the product is required. QbD has brought a realization of the importance of the analytical, nonclinical and animal studies in establishing these linkages and has led to the creation of novel approaches.

Defining process design space. The overall approach toward process characterization involves three key steps. First, risk analysis is performed to identify parameters for process characterization. Second, studies are designed using design of experiments (DOE), such that the data are amenable for use in understanding and defining the design space. And third, the studies are executed and the results analyzed to determine the importance of the parameters as well as their role in establishing design space.

Failure mode and effects analysis (FMEA) is commonly used to assess the potential degree of risk for every operating parameter in a systematic manner and to prioritize the activities, such as experiments, necessary to understand the impact of these parameters on overall process performance. A team consisting of representatives from process development, manufacturing and other relevant disciplines performs an assessment to determine severity, occurrence and detection. The severity score measures the seriousness of a particular failure and is based on an estimate of the severity of the potential failure effect at a local or process level and the potential failure effect at end product use or patient level. Occurrence and detection scores are based on an excursion (manufacturing deviation) outside the operating range that results in the identified failure. Although the occurrence score measures how frequently the failure might occur, the detection score indicates the probability of timely detection and correction of the excursion or the probability of detection before end product use. All three scores are multiplied to provide a risk priority number (RPN) and the RPN scores are then ranked to identify the parameters with a high enough risk to merit process characterization.  FMEA outcome for a process chromatography step in a biotech process. RPN scores are calculated and operating parameters with an RPN score >50 are characterized using a qualified scaled-down model. For the case study presented here, these include gradient slope, temperature, flow rate, product loading, end of pool collection, buffer A pH, start of pool collection, volume of wash 1, buffer B pH, buffer C pH and bed height. Process characterization focused on parameters such as temperature, that have a high impact on the process (severity = 6), occur frequently in the manufacturing plant (occurrence = 6) and are difficult to quickly correct if detected (detection = 7). In contrast, parameters such as equilibration volume, with a low impact on the process (severity = 3), low occurrence (occurrence = 2) and a limited ability to detect and correct (detection = 5), were not examined in process characterization.

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Scientists Find Sniffing Rosemary Can Increase Memory By 75%

 Ayurveda  Comments Off on Scientists Find Sniffing Rosemary Can Increase Memory By 75%
Aug 032014
 

Scientists Find Sniffing Rosemary Can Increase Memory By 75 Percent

Rosemary is a wonderful herb with a tradition of use spanning millennia. It has innumerable uses in both the kitchen and in herbal medicine.

read at

http://www.herbs-info.com/blog/scientists-find-sniffing-rosemary-can-increase-memory-by-75/

 

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Cystic Fibrosis Letdown Explained Drug Combo: Cell studies suggest way to boost clinical outcomes

 Uncategorized  Comments Off on Cystic Fibrosis Letdown Explained Drug Combo: Cell studies suggest way to boost clinical outcomes
Jul 312014
 
09230-notw8-therapy

Combination therapies are a promising strategy for correcting the most common gene mutation responsible for cystic fibrosis. A “corrector” drug rescues a misfolded ion channel (purple squiggle) and brings it to the cell membrane (yellow). Then, a “potentiator” drug coaxes the channel open, allowing more chloride ions (green) out.
Credit: Sci. Transl. Med.
One of the two drugs in a promising cystic fibrosis therapy might be undoing the beneficial effects of the other, two studies suggest. The work, conducted in cells, may explain the modest results from a major clinical trial and provide an avenue for improved drugs.
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ROFECOXIB

 Uncategorized  Comments Off on ROFECOXIB
Jul 312014
 

Rofecoxib.svg

ROFECOXIB

MK-966, MK-0966, Vioxx

162011-90-7

C17-H14-O4-S
314.3596

Rofecoxib /ˌrɒfɨˈkɒksɪb/ is a nonsteroidal anti-inflammatory drug (NSAID) that has now been withdrawn over safety concerns. It was marketed by Merck & Co. to treat osteoarthritis, acute pain conditions, and dysmenorrhoea. Rofecoxib was approved by the Food and Drug Administration (FDA) on May 20, 1999, and was marketed under the brand names Vioxx, Ceoxx, and Ceeoxx.

Rofecoxib
Rofecoxib.svg
Rofecoxib-3D.png
Systematic (IUPAC) name
4-(4-methylsulfonylphenyl)-3-phenyl-5H-furan-2-one
Clinical data
Pregnancy cat. C (AU)
Legal status Prescription Only (S4) (AU)withdrawn
Routes oral
Pharmacokinetic data
Bioavailability 93%
Protein binding 87%
Metabolism hepatic
Half-life 17 hours
Excretion biliary/renal
Identifiers
CAS number 162011-90-7 Yes
ATC code M01AH02
PubChem CID 5090
DrugBank DB00533
ChemSpider 4911 Yes
UNII 0QTW8Z7MCR Yes
 
Chemical data
Formula C17H14O4S 
Mol. mass 314.357 g/mol

Rofecoxib gained widespread acceptance among physicians treating patients with arthritis and other conditions causing chronic or acute pain. Worldwide, over 80 million people were prescribed rofecoxib at some time.[1]

On September 30, 2004, Merck withdrew rofecoxib from the market because of concerns about increased risk of heart attack and stroke associated with long-term, high-dosage use. Merck withdrew the drug after disclosures that it withheld information about rofecoxib’s risks from doctors and patients for over five years, resulting in between 88,000 and 140,000 cases of serious heart disease.[2] Rofecoxib was one of the most widely used drugs ever to be withdrawn from the market. In the year before withdrawal, Merck had sales revenue of US$2.5 billion from Vioxx.[3] Merck reserved $970 million to pay for its Vioxx-related legal expenses through 2007, and have set aside $4.85bn for legal claims from US citizens.

Rofecoxib was available on prescription in both tablet-form and as an oral suspension. It was available by injection for hospital use.

 

Mode of action

See also: Cyclooxygenase

Cyclooxygenase (COX) has two well-studied isoforms, called COX-1 and COX-2. COX-1 mediates the synthesis of prostaglandinsresponsible for protection of the stomach lining, while COX-2 mediates the synthesis of prostaglandins responsible for pain and inflammation. By creating “selective” NSAIDs that inhibit COX-2, but not COX-1, the same pain relief as traditional NSAIDs is offered, but with greatly reduced risk of fatal or debilitating peptic ulcers. Rofecoxib is a selective COX-2 inhibitor, or “coxib”.

Others include Merck’s etoricoxib (Arcoxia), Pfizer’s celecoxib (Celebrex) and valdecoxib (Bextra). Interestingly, at the time of its withdrawal, rofecoxib was the only coxib with clinical evidence of its superior gastrointestinal adverse effect profile over conventional NSAIDs. This was largely based on the VIGOR (Vioxx GI Outcomes Research) study, which compared the efficacy and adverse effect profiles of rofecoxib and naproxen.[4]

Pharmacokinetics

The therapeutic recommended dosages were 12.5, 25, and 50 mg with an approximate bioavailability of 93%.[5][6][7] Rofecoxib crossed the placenta and blood–brain barrier,[5][6][8]and took 1–3 hours to reach peak plasma concentration with an effective half-life (based on steady-state levels) of approximately 17 hours.[5][7][9] The metabolic products are cis-dihydro and trans-dihydro derivatives of rofecoxib[5][9] which are primarily excreted through urine.

Fabricated efficacy studies

On March 11, 2009, Scott S. Reuben, former chief of acute pain at Baystate Medical Center, Springfield, Mass., revealed that data for 21 studies he had authored for the efficacy of the drug (along with others such as celecoxib) had been fabricated in order to augment the analgesic effects of the drugs. There is no evidence that Reuben colluded with Merck in falsifying his data. Reuben was also a former paid spokesperson for the drug company Pfizer (which owns the intellectual property rights for marketing celecoxib in the United States). The retracted studies were not submitted to either the FDA or the European Union’s regulatory agencies prior to the drug’s approval. Drug manufacturer Merckhad no comment on the disclosure.[10]

Adverse drug reactions

VIOXX sample blister pack.jpg

Aside from the reduced incidence of gastric ulceration, rofecoxib exhibits a similar adverse effect profile to other NSAIDs.

Prostaglandin is a large family of lipids. Prostaglandin I2/PGI2/prostacyclin is just one member of it. Prostaglandins other than PGI2 (such as PGE2) also play important roles in vascular tone regulation. Prostacyclin/thromboxane are produced by both COX-1 and COX-2, and rofecoxib suppresses just COX-2 enzyme, so there is no reason to believe that prostacyclin levels are significantly reduced by the drug. And there is no reason to believe that only the balance between quantities of prostacyclin and thromboxane is the determinant factor for vascular tone.[11] Indeed Merck has stated that there was no effect on prostacyclin production in blood vessels in animal testing.[12] Other researchers have speculated that the cardiotoxicity may be associated with maleic anhydride metabolites formed when rofecoxib becomes ionized under physiological conditions. (Reddy & Corey, 2005)

Adverse cardiovascular events

VIGOR study and publishing controversy

The VIGOR (Vioxx GI Outcomes Research) study, conducted by Bombardier, et al., which compared the efficacy and adverse effect profiles of rofecoxib and naproxen, had indicated a significant 4-fold increased risk of acute myocardial infarction (heart attack) in rofecoxib patients when compared with naproxen patients (0.4% vs 0.1%, RR 0.25) over the 12 month span of the study. The elevated risk began during the second month on rofecoxib. There was no significant difference in the mortality from cardiovascular events between the two groups, nor was there any significant difference in the rate of myocardial infarction between the rofecoxib and naproxen treatment groups in patients without high cardiovascular risk. The difference in overall risk was by the patients at higher risk of heart attack, i.e. those meeting the criteria for low-dose aspirin prophylaxis of secondary cardiovascular events (previous myocardial infarction, angina, cerebrovascular accident, transient ischemic attack, or coronary artery bypass).

Merck’s scientists interpreted the finding as a protective effect of naproxen, telling the FDA that the difference in heart attacks “is primarily due to” this protective effect (Targum, 2001). Some commentators have noted that naproxen would have to be three times as effective as aspirin to account for all of the difference (Michaels 2005), and some outside scientists warned Merck that this claim was implausible before VIGOR was published.[13] No evidence has since emerged for such a large cardioprotective effect of naproxen, although a number of studies have found protective effects similar in size to those of aspirin.[14][15] Though Dr. Topol’s 2004 paper criticized Merck’s naproxen hypothesis, he himself co-authored a 2001 JAMA article stating “because of the evidence for an antiplatelet effect of naproxen, it is difficult to assess whether the difference in cardiovascular event rates in VIGOR was due to a benefit from naproxen or to a prothrombotic effect from rofecoxib.” (Mukherjee, Nissen and Topol, 2001.)

The results of the VIGOR study were submitted to the United States Food and Drug Administration (FDA) in February 2001. In September 2001, the FDA sent a warning letter to the CEO of Merck, stating, “Your promotional campaign discounts the fact that in the VIGOR study, patients on Vioxx were observed to have a four to five fold increase in myocardial infarctions (MIs) compared to patients on the comparator non-steroidal anti-inflammatory drug (NSAID), Naprosyn (naproxen).”[16] This led to the introduction, in April 2002, of warnings on Vioxx labeling concerning the increased risk of cardiovascular events (heart attack and stroke).

Months after the preliminary version of VIGOR was published in the New England Journal of Medicine, the journal editors learned that certain data reported to the FDA were not included in the NEJM article. Several years later, when they were shown a Merck memo during the depositions for the first federal Vioxx trial, they realized that these data had been available to the authors months before publication. The editors wrote an editorial accusing the authors of deliberately withholding the data.[17] They released the editorial to the media on December 8, 2005, before giving the authors a chance to respond. NEJM editor Gregory Curfman explained that the quick release was due to the imminent presentation of his deposition testimony, which he feared would be misinterpreted in the media. He had earlier denied any relationship between the timing of the editorial and the trial. Although his testimony was not actually used in the December trial, Curfman had testified well before the publication of the editorial.[18]

The editors charged that “more than four months before the article was published, at least two of its authors were aware of critical data on an array of adverse cardiovascular events that were not included in the VIGOR article.” These additional data included three additional heart attacks, and raised the relative risk of Vioxx from 4.25-fold to 5-fold. All the additional heart attacks occurred in the group at low risk of heart attack (the “aspirin not indicated” group) and the editors noted that the omission “resulted in the misleading conclusion that there was a difference in the risk of myocardial infarction between the aspirin indicated and aspirin not indicated groups.” The relative risk for myocardial infarctions among the aspirin not indicated patients increased from 2.25 to 3 (although it remained statitistically insignificant). The editors also noted a statistically significant (2-fold) increase in risk for serious thromboembolic events for this group, an outcome that Merck had not reported in the NEJM, though it had disclosed that information publicly in March 2000, eight months before publication.[19]

The authors of the study, including the non-Merck authors, responded by claiming that the three additional heart attacks had occurred after the prespecified cutoff date for data collection and thus were appropriately not included. (Utilizing the prespecified cutoff date also meant that an additional stroke in the naproxen population was not reported.) Furthermore, they said that the additional data did not qualitatively change any of the conclusions of the study, and the results of the full analyses were disclosed to the FDA and reflected on the Vioxx warning label. They further noted that all of the data in the “omitted” table were printed in the text of the article. The authors stood by the original article.[20]

NEJM stood by its editorial, noting that the cutoff date was never mentioned in the article, nor did the authors report that the cutoff for cardiovascular adverse events was before that for gastrointestinal adverse events. The different cutoffs increased the reported benefits of Vioxx (reduced stomach problems) relative to the risks (increased heart attacks).[19]

Some scientists have accused the NEJM editorial board of making unfounded accusations.[21][22] Others have applauded the editorial. Renowned research cardiologist Eric Topol,[23] a prominent Merck critic, accused Merck of “manipulation of data” and said “I think now the scientific misconduct trial is really fully backed up”.[24] Phil Fontanarosa, executive editor of the prestigious Journal of the American Medical Association, welcomed the editorial, saying “this is another in the long list of recent examples that have generated real concerns about trust and confidence in industry-sponsored studies”.[25]

On May 15, 2006, the Wall Street Journal reported that a late night email, written by an outside public relations specialist and sent to Journal staffers hours before the Expression of Concern was released, predicted that “the rebuke would divert attention to Merck and induce the media to ignore the New England Journal of Medicine‘s own role in aiding Vioxx sales.”[26]

“Internal emails show the New England Journal’s expression of concern was timed to divert attention from a deposition in which Executive Editor Gregory Curfman made potentially damaging admissions about the journal’s handling of the Vioxx study. In the deposition, part of the Vioxx litigation, Dr. Curfman acknowledged that lax editing might have helped the authors make misleading claims in the article.” The Journal stated that NEJM‘s “ambiguous” language misled reporters into incorrectly believing that Merck had deleted data regarding the three additional heart attacks, rather than a blank table that contained no statistical information; “the New England Journal says it didn’t attempt to have these mistakes corrected.”[26]

Alzheimer’s studies

In 2000 and 2001, Merck conducted several studies of rofecoxib aimed at determining if the drug slowed the onset of Alzheimer’s disease. Merck has placed great emphasis on these studies on the grounds that they are relatively large (almost 3000 patients) and compared rofecoxib to a placebo rather than to another pain reliever. These studies found an elevated death rate among rofecoxib patients, although the deaths were not generally heart-related. However, they did not find any elevated cardiovascular risk due to rofecoxib.[27] Before 2004, Merck cited these studies as providing evidence, contrary to VIGOR, of rofecoxib’s safety.

APPROVe study

In 2001, Merck commenced the APPROVe (Adenomatous Polyp PRevention On Vioxx) study, a three-year trial with the primary aim of evaluating the efficacy of rofecoxib for theprophylaxis of colorectal polyps. Celecoxib had already been approved for this indication, and it was hoped to add this to the indications for rofecoxib as well. An additional aim of the study was to further evaluate the cardiovascular safety of rofecoxib.

The APPROVe study was terminated early when the preliminary data from the study showed an increased relative risk of adverse thrombotic cardiovascular events (includingheart attack and stroke), beginning after 18 months of rofecoxib therapy. In patients taking rofecoxib, versus placebo, the relative risk of these events was 1.92 (rofecoxib 1.50 events vs placebo 0.78 events per 100 patient years). The results from the first 18 months of the APPROVe study did not show an increased relative risk of adverse cardiovascular events. Moreover, overall and cardiovascular mortality rates were similar between the rofecoxib and placebo populations.[28]

In summary, the APPROVe study suggested that long-term use of rofecoxib resulted in nearly twice the risk of suffering a heart attack or stroke compared to patients receiving a placebo.

Other studies

Pre-approval Phase III clinical trials, like the APPROVe study, showed no increased relative risk of adverse cardiovascular events for the first eighteen months of rofecoxib usage (Merck, 2004). Others have pointed out that “study 090,” a pre-approval trial, showed a 3-fold increase in cardiovascular events compared to placebo, a 7-fold increase compared to nabumetone (another [NSAID]), and an 8-fold increase in heart attacks and strokes combined compared to both control groups.[29][30] Although this was a relatively small study and only the last result was statistically significant, critics have charged that this early finding should have prompted Merck to quickly conduct larger studies of rofecoxib’s cardiovascular safety. Merck notes that it had already begun VIGOR at the time Study 090 was completed. Although VIGOR was primarily designed to demonstrate new uses for rofecoxib, it also collected data on adverse cardiovascular outcomes.

Several very large observational studies have also found elevated risk of heart attack from rofecoxib. For example, a recent retrospective study of 113,000 elderly Canadians suggested a borderline statistically significant increased relative risk of heart attacks of 1.24 from Vioxx usage, with a relative risk of 1.73 for higher-dose Vioxx usage. (Levesque, 2005). Another study, using Kaiser Permanente data, found a 1.47 relative risk for low-dose Vioxx usage and 3.58 for high-dose Vioxx usage compared to current use of celecoxib, though the smaller number was not statistically significant, and relative risk compared to other populations was not statistically significant. (Graham, 2005).

Furthermore, a more recent meta-study of 114 randomized trials with a total of 116,000+ participants, published in JAMA, showed that Vioxx uniquely increased risk of renal (kidney) disease, and heart arrhythmia.[31]

Other COX-2 inhibitors

Any increased risk of renal and arrhythmia pathologies associated with the class of COX-2 inhibitors, e.g. celecoxib (Celebrex), valdecoxib (Bextra), parecoxib (Dynastat),lumiracoxib, and etoricoxib is not evident,[31] although smaller studies[32][33] had demonstrated such effects earlier with the use of celecoxib, valdecoxib and parecoxib.

Nevertheless, it is likely that trials of newer drugs in the category will be extended in order to supply additional evidence of cardiovascular safety. Examples are some more specific COX-2 inhibitors, including etoricoxib (Arcoxia) and lumiracoxib (Prexige), which are currently (circa 2005) undergoing Phase III/IV clinical trials.

Besides, regulatory authorities worldwide now require warnings about cardiovascular risk of COX-2 inhibitors still on the market. For example, in 2005, EU regulators required the following changes to the product information and/or packaging of all COX-2 inhibitors:[34]

  • Contraindications stating that COX-2 inhibitors must not be used in patients with established ischaemic heart disease and/or cerebrovascular disease (stroke), and also in patients with peripheral arterial disease
  • Reinforced warnings to healthcare professionals to exercise caution when prescribing COX-2 inhibitors to patients with risk factors for heart disease, such as hypertension, hyperlipidaemia (high cholesterol levels), diabetes and smoking
  • Given the association between cardiovascular risk and exposure to COX-2 inhibitors, doctors are advised to use the lowest effective dose for the shortest possible duration of treatment

Other NSAIDs

Since the withdrawal of Vioxx it has come to light that there may be negative cardiovascular effects with not only other COX-2 inhibitiors, but even the majority of other NSAIDs. It is only with the recent development of drugs like Vioxx that drug companies have carried out the kind of well executed trials that could establish such effects and these sort of trials have never been carried out in older “trusted” NSAIDs such as ibuprofen, diclofenac and others. The possible exceptions may be aspirin and naproxen due to their anti-platelet aggregation properties.

Withdrawal

Due to the findings of its own APPROVe study, Merck publicly announced its voluntary withdrawal of the drug from the market worldwide on September 30, 2004.[35]

In addition to its own studies, on September 23, 2004 Merck apparently received information about new research by the FDA that supported previous findings of increased risk of heart attack among rofecoxib users (Grassley, 2004). FDA analysts estimated that Vioxx caused between 88,000 and 139,000 heart attacks, 30 to 40 percent of which were probably fatal, in the five years the drug was on the market.[36]

On November 5, the medical journal The Lancet published a meta-analysis of the available studies on the safety of rofecoxib (Jüni et al., 2004). The authors concluded that, owing to the known cardiovascular risk, rofecoxib should have been withdrawn several years earlier. The Lancet published an editorial which condemned both Merck and the FDA for the continued availability of rofecoxib from 2000 until the recall. Merck responded by issuing a rebuttal of the Jüni et al. meta-analysis that noted that Jüni omitted several studies that showed no increased cardiovascular risk. (Merck & Co., 2004).

In 2005, advisory panels in both the U.S. and Canada encouraged the return of rofecoxib to the market, stating that rofecoxib’s benefits outweighed the risks for some patients. The FDA advisory panel voted 17-15 to allow the drug to return to the market despite being found to increase heart risk. The vote in Canada was 12-1, and the Canadian panel noted that the cardiovascular risks from rofecoxib seemed to be no worse than those from ibuprofen—though the panel recommended that further study was needed for all NSAIDs to fully understand their risk profiles. Notwithstanding these recommendations, Merck has not returned rofecoxib to the market.[37]

In 2005, Merck retained Debevoise & Plimpton LLP to investigate Vioxx study results and communications conducted by Merck. Through the report, it was found that Merck’s senior management acted in good faith, and that the confusion over the clinical safety of Vioxx was due to the sales team’s overzealous behavior. The report that was filed gave a timeline of the events surrounding Vioxx and showed that Merck intended to operate honestly throughout the process. Any mistakes that were made regarding the mishandling of clinical trial results and withholding of information was the result of oversight, not malicious behavior. The Martin Report did conclude that the Merck’s marketing team exaggerated the safety of Vioxx and replaced truthful information with sales tactics.[citation needed] The report was published in February 2006, and Merck was satisfied with the findings of the report and promised to consider the recommendations contained in the Martin Report. Advisers to the US Food and Drug Administration (FDA) have voted, by a narrow margin, that it should not ban Vioxx — the painkiller withdrawn by drug-maker Merck.

They also said that Pfizer’s Celebrex and Bextra, two other members of the family of painkillers known as COX-2 inhibitors, should remain available, despite the fact that they too boost patients’ risk of heart attack and stroke. url = http://www.nature.com/drugdisc/news/articles/433790b.html The recommendations of the arthritis and drug safety advisory panel offer some measure of relief to the pharmaceutical industry, which has faced a barrage of criticism for its promotion of the painkillers. But the advice of the panel, which met near Washington DC over 16–18 February, comes with several strings attached.

For example, most panel members said that manufacturers should be required to add a prominent warning about the drugs’ risks to their labels; to stop direct-to-consumer advertising of the drugs; and to include detailed, written risk information with each prescription. The panel also unanimously stated that all three painkillers “significantly increase the risk of cardiovascular events”.

The panel voted 17 to 15 against banning Vioxx (rofecoxib) entirely; the vote on Bextra (valdecoxib) was 17 to 13 with 2 abstentions; Celebrex (celecoxib) was endorsed 31 to 1. Shares of Merck, based in Whitehouse Station, New Jersey, and New York-based Pfizer closed up 13% and 7% respectively on 18 February, 2013, the day of the votes.

The FDA is expected to act on the recommendations within weeks. Although the agency usually follows the recommendations of its outside advisers, it is not bound to do so. A top official said that, in light of the closeness of some of the votes, the agency will examine the panel members’ comments in detail before deciding what to do.

An official from Merck said during the meeting that it would consider reintroducing Vioxx, which it withdrew in September 2004. On April 7, 2005, Pfizer withdrew Bextra from the U.S. market on recommendation by the FDA. Pfizer’s other painkiller, Celebrex, is still on the market.

Litigation

As of March 2006, there had been over 10,000 cases and 190 class actions filed against Merck[citation needed] over adverse cardiovascular events associated with rofecoxib and the adequacy of Merck’s warnings. The first wrongful death trial, Rogers v. Merck, was scheduled in Alabama in the spring of 2005, but was postponed after Merck argued that the plaintiff had falsified evidence of rofecoxib use.[1]

On August 19, 2005, a jury in Texas voted 10-2 to hold Merck liable for the death of Robert Ernst, a 59-year-old man who allegedly died of a rofecoxib-induced heart attack. The plaintiffs’ lead attorney was Mark Lanier. Merck argued that the death was due to cardiac arrhythmia, which had not been shown to be associated with rofecoxib use. The jury awarded Carol Ernst, widow of Robert Ernst, $253.4 million in damages. This award will almost certainly be capped at no more than US$26.1 million because of punitive damages limits under Texas law.[2] As of March 2006, the plaintiff had yet to ask the court to enter a judgment on the verdict; Merck has stated that it will appeal.

On November 3, 2005, Merck won the second case Humeston v. Merck, a personal injury case, in Atlantic City, New Jersey. The plaintiff experienced a mild myocardial infarction and claimed that rofecoxib was responsible, after having taken it for two months. Merck argued that there was no evidence that rofecoxib was the cause of Humeston’s injury and that there is no scientific evidence linking rofecoxib to cardiac events with short durations of use. The jury ruled that Merck had adequately warned doctors and patients of the drug’s risk.[3]

The first federal trial on rofecoxib, Plunkett v. Merck, began on November 29, 2005 in Houston. The trial ended in a hung jury and a mistrial was declared on December 12, 2005. According to the Wall Street Journal, the jury hung by an eight to one majority, favoring the defense. Upon retrial in February 2006 in New Orleans, where the Vioxx multidistrict litigation (MDL) is based, a jury found Merck not liable, even though the plaintiffs had the NEJM editor testify as to his objections to the VIGOR study.

On January 30, 2006, a New Jersey state court dismissed a case brought by Edgar Lee Boyd, who blamed Vioxx for gastrointestinal bleeding that he experienced after taking the drug. The judge said that Boyd failed to prove the drug caused his stomach pain and internal bleeding.

In January 2006, Garza v. Merck began trial in Rio Grande City, Texas. The plaintiff, a 71-year-old smoker with heart disease, had a fatal heart attack three weeks after finishing a one-week sample of rofecoxib. On April 21, 2006 the jury awarded the plaintiff $7 million compensatory and $25 million punitive. The Texas state court of appeals in San Antonio later rules Garza’s fatal heart attack probably resulted from pre-existing health conditions unrelated to his taking of Vioxx, thus reversing the $32 million jury award.[4]

On April 5, 2006, the jury held Merck liable for the heart attack of 77-year-old John McDarby, and awarded Mr McDarby $4.5 million in compensatory damages based on Merck’s failure to properly warn of Vioxx safety risks. After a hearing on April 11, 2006, the jury also awarded Mr McDarby an additional $9 million in punitive damages. The same jury found Merck not liable for the heart attack of 60-year-old Thomas Cona, a second plaintiff in the trial, but was liable for fraud in the sale of the drug to Cona.

Merck has reserved $970 million to pay for its Vioxx-related legal expenses through 2007, and have set aside $4.85bn for legal claims from US citizens. Patients who claim to have suffered as a result of taking Vioxx in countries outside the US are campaigning for this to be extended.

In March 2010, an Australian class-action lawsuit against Merck ruled that Vioxx doubled the risk of heart attacks, and that Merck had breached the Trade Practices Act by selling a drug which was unfit for sale.[38]

In November 2011, Merck announced a civil settlement with the US Attorney’s Office for the District of Massachusetts, and individually with 43 US states and the District of Columbia, to resolve civil claims relating to Vioxx.[5] Under the terms of the settlement, Merck agreed to pay two-thirds of a previously recorded $950 million reserve charge in exchange for release from civil liability. Litigation with seven additional states remains outstanding. Under separate criminal proceedings, Merck plead guilty to a federal misdemeanor charge relating to the marketing of the drug across state lines, incurring a fine of $321.6 million.[6]

Other effects

Rofecoxib was shown to improve premenstrual acne vulgaris in a placebo controlled study.[39]

Synthesis

Rofecoxib synthesis.[40]

 

,,,,,,,,,,,,,,,,,

The oxidation of 4- (methylsulfanyl) acetophenone (X) with monoperoxyphthalic acid (MMPP) in dichloro-methane / methanol gives the corresponding sulfone (XI), which is brominated with Br2 / AlCl3 in chloroform, yielding the expected phenacyl bromide ( XII). Finally, this compound is cyclocondensed with phenylacetic acid (I) by means of 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) and triethylamine in acetonitrile. 5) Reaction of [4- (methylsulfonyl ) phenyl] phenylacetyl-ene (XIII) with CO catalyzed by Rh4 (CO) 12 in THF at 100 C in a stainless steel autoclave at 100 Atm pressure, followed by a chromatographic separation in a silicagel column to eliminate the undesired regioisomer.

 

……………….

The synthesis of rofecoxib can be performed by several different ways: 1) The condensation of phenylacetic acid (I) with ethyl bromoacetate (II) by means of triethylamine in THF yields 2- (phenylacetoxy) acetic acid ethyl ester (III), which is cyclized to the hydroxyfuranone (IV) by means of potassium tert-butoxide in tert-butanol. The reaction of (IV) with triflic anhydride and diisopropylethylamine in dichloro-methane affords the corresponding triflate (V), which by reaction with LiBr in hot acetone yields the bromofuranone (VI) The condensation of (VI) with 4- (methylsulfanyl) phenylboronic acid (VII) by means of Na2CO3 and Pd (Ph3P) 4 in hot toluene gives 4- [4- (methylsulfanyl) -phenyl]. – 3-phenylfuran-2 (5H) -one (VIII), which is finally oxidized with 2KHSO5.KHSO4.K2SO4 (oxone). 2) The intermediate (VIII) can also be obtained by condensation of triflate (V) with boronic acid ( VII) by means of Na2CO3 and Pd (Ph3P) 4 in hot toluene. 3) The intermediate (VIII) can also be synthesized by the reaction of triflate (V) with tetramethylammonium chloride, giving the chlorofuranone (IX), which is then condensed with boronic acid (VII) as before.

Footnotes

  1. Jump up^ http://www.npr.org/templates/story/story.php?storyId=4054991
  2. Jump up^ “Up to 140,000 heart attacks linked to Vioxx.”. New Scientist. 2005-01-25. p. 1.
  3. Jump up^ “Merck Sees Slightly Higher 2007 Earnings”. New York Times. Reuters. 2006-12-07. p. A1.
  4. Jump up^ Bombardier, C.; Laine, L.; Reicin, A.; Shapiro, D.; Burgos-Vargas, R.; Davis, B.; Day, R.; Ferraz, M. B.; Hawkey, C. J.; Hochberg, M. C.; Kvien, T. K.; Schnitzer, T. J.; Vigor Study, G. (2000). “Comparison of Upper Gastrointestinal Toxicity of Rofecoxib and Naproxen in Patients with Rheumatoid Arthritis”. New England Journal of Medicine 343 (21): 1520–1528, 2 1528 following 1528. doi:10.1056/NEJM200011233432103. PMID 11087881. edit
  5. ^ Jump up to:a b c d Merck & Co. VIOXX (rofecoxib tablets and oral suspension). Accessed at: http://www.merck.com/product/usa/pi_circulars/v/vioxx/vioxx_pi.pdf 01 Feb 2010
  6. ^ Jump up to:a b Gold Standard Inc. Rofecoxib Vioxx Accessed at: http://www.mdconsult.com/das/pharm/body/181267313-3/946823742/full/2399 01 Feb 2010
  7. ^ Jump up to:a b Davies, N. M.; Teng, X. W.; Skjodt, N. M. (2003). “Pharmacokinetics of rofecoxib: a specific cyclo-oxygenase-2 inhibitor”. Clinical pharmacokinetics 42 (6): 545–556.PMID 12793839. edit
  8. Jump up^ Padi, S.; Kulkarni, S. (2004). “Differential effects of naproxen and rofecoxib on the development of hypersensitivity following nerve injury in rats”. Pharmacology, Biochemistry, and Behavior 79 (2): 349–358. doi:10.1016/j.pbb.2004.08.005. PMID 15501312. edit
  9. ^ Jump up to:a b Scott, L. J.; Lamb, H. M. (1999). “Rofecoxib”. Drugs 58 (3): 499–505; discussion 506–7. doi:10.2165/00003495-199958030-00016. PMID 10493277. edit
  10. Jump up^ Winstein, Keith J. (March 11, 2009). “Top Pain Scientist Fabricated Data in Studies, Hospital Says”. The Wall Street Journal.
  11. Jump up^ Vane, J.; Bakhle, Y.; Botting, R. (1998). “Cyclooxygenases 1 and 2”. Annual review of pharmacology and toxicology 38: 97–120. doi:10.1146/annurev.pharmtox.38.1.97.PMID 9597150. edit
  12. Jump up^ sfgate.com
  13. Jump up^ www.saferdrugsnow.org
  14. Jump up^ Karha, J.; Topol, E. J. (2004). “The sad story of Vioxx, and what we should learn from it”. Cleveland Clinic journal of medicine 71 (12): 933–934, 936, 934–9.doi:10.3949/ccjm.71.12.933. PMID 15641522. edit
  15. Jump up^ Solomon, D. H.; Glynn, R. J.; Levin, R.; Avorn, J. (2002). “Nonsteroidal anti-inflammatory drug use and acute myocardial infarction”. Archives of Internal Medicine 162 (10): 1099–1104.doi:10.1001/archinte.162.10.1099. PMID 12020178. edit
  16. Jump up^http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/EnforcementActivitiesbyFDA/WarningLettersandNoticeofViolationLetterstoPharmaceuticalCompanies/UCM166383.pdf
  17. Jump up^ Curfman, G.; Morrissey, S.; Drazen, J. (2005). “Expression of concern: Bombardier et al., “Comparison of upper gastrointestinal toxicity of rofecoxib and naproxen in patients with rheumatoid arthritis,” N Engl J Med 2000;343:1520-8″. The New England Journal of Medicine 353 (26): 2813–2814. doi:10.1056/NEJMe058314. PMID 16339408. edit
  18. Jump up^ http://www.forbes.com/work/feeds/ap/2006/02/13/ap2523250.html. Missing or empty |title= (help)[dead link]
  19. ^ Jump up to:a b Curfman, G.; Morrissey, S.; Drazen, J. (2006). “Expression of concern reaffirmed”. The New England Journal of Medicine 354 (11): 1193. doi:10.1056/NEJMe068054.PMID 16495386. edit
  20. Jump up^ Bombardier, C.; Laine, L.; Burgos-Vargas, R.; Davis, B.; Day, R.; Ferraz, M.; Hawkey, C.; Hochberg, M.; Kvien, T.; Schnitzer, T. J.; Weaver, A. (2006). “Response to expression of concern regarding VIGOR study”. The New England Journal of Medicine 354 (11): 1196–1199. doi:10.1056/NEJMc066096. PMID 16495387. edit
  21. Jump up^ http://pipeline.corante.com/archives/2006/02/22/nejm_vs_its_contributors_round_two.php
  22. Jump up^ http://dimer.tamu.edu/simplog/archive.php?blogid=3&pid=3293
  23. Jump up^ http://genetics.case.edu/faculty2.php?fac=ejt9
  24. Jump up^ http://www.medicinenet.com/script/main/art.asp?articlekey=56384&page=2
  25. Jump up^ http://www.beasleyallen.com/news/vioxx-plaintiffs-seek-mistrial-after-allegation-on-merck-study/
  26. ^ Jump up to:a b David Armstrong (2006-05-15). “How the New England Journal Missed Warning Signs on Vioxx”. Wall Street Journal. p. A1.
  27. Jump up^ Konstam, M. A.; Weir, M. R.; Reicin, A.; Shapiro, D.; Sperling, R. S.; Barr, E.; Gertz, B. J. (2001). “Cardiovascular thrombotic events in controlled, clinical trials of rofecoxib”. Circulation104 (19): 2280–2288. doi:10.1161/hc4401.100078. PMID 11696466. edit
  28. Jump up^ Bresalier, R.; Sandler, R.; Quan, H.; Bolognese, J.; Oxenius, B.; Horgan, K.; Lines, C.; Riddell, R.; Morton, D.; Lanas, A.; Konstam, M. A.; Baron, J. A.; Adenomatous Polyp Prevention on Vioxx (APPROVe) Trial Investigators (2005). “Cardiovascular events associated with rofecoxib in a colorectal adenoma chemoprevention trial”. The New England Journal of Medicine 352(11): 1092–1102. doi:10.1056/NEJMoa050493. PMID 15713943. edit
  29. Jump up^ http://www.fda.gov/ohrms/dockets/ac/01/briefing/3677b2_06_cardio.pdf
  30. Jump up^ Wolfe, M. M. (2004). “Rofecoxib, Merck, and the FDA”. The New England Journal of Medicine 351 (27): 2875–2878; author 2878 2875–2878. doi:10.1056/NEJM200412303512719.PMID 15625749. edit
  31. ^ Jump up to:a b Zhang, J.; Ding, E.; Song, Y. (2006). “Adverse effects of cyclooxygenase 2 inhibitors on renal and arrhythmia events: meta-analysis of randomized trials”. Journal of the American Medical Association 296 (13): 1619–1632. doi:10.1001/jama.296.13.jrv60015. PMID 16968832. edit
  32. Jump up^ Solomon, S.; McMurray, J.; Pfeffer, M.; Wittes, J.; Fowler, R.; Finn, P.; Anderson, W.; Zauber, A.; Hawk, E.; Bertagnolli, M.; Adenoma Prevention with Celecoxib (APC) Study Investigators (2005). “Cardiovascular risk associated with celecoxib in a clinical trial for colorectal adenoma prevention”. The New England Journal of Medicine 352 (11): 1071–1080.doi:10.1056/NEJMoa050405. PMID 15713944. edit
  33. Jump up^ Nussmeier, N.; Whelton, A.; Brown, M.; Langford, R.; Hoeft, A.; Parlow, J.; Boyce, S.; Verburg, K. (2005). “Complications of the COX-2 inhibitors parecoxib and valdecoxib after cardiac surgery”. The New England Journal of Medicine 352 (11): 1081–1091. doi:10.1056/NEJMoa050330. PMID 15713945. edit
  34. Jump up^ “European Medicines Agency concludes action on COX-2 inhibitors” (pdf). European Medicines Agency. Retrieved 2008-04-16.
  35. Jump up^ “Merck Announces Voluntary Worldwide Withdrawal of VIOXX” (pdf). Retrieved 2008-04-16.
  36. Jump up^ “Congress Questions Vioxx, FDA”. PBS NewsHour. 2004-11-18. Retrieved 2013-06-03.
  37. Jump up^ “SUMMARY: Report of the Expert Advisory Panel on the Safety of Cox-2 Selective Non-steroidal Anti-Inflammatory Drugs (NSAIDs)”. Health Canada. 2005-07-06. Retrieved 2011-06-04.
  38. Jump up^ Drug unfit for sale, says judge in compo case The Age, March 6, 2010
  39. Jump up^ http://bioline.utsc.utoronto.ca/archive/00002693/01/dv04120.pdf#search=%22acne%20rofecoxib%22
  40. Jump up^ http://vioxxlawyer.org/rofecoxib-synthesis/

References

  • FDA (2005). “Summary minutes for the February 16, 17 and 18, 2005, Joint meeting of the Arthritis Advisory Committee and the Drug Safety and Risk Management Advisory Committee.” Published on the internet, March 2005. Link
  • Fitzgerald GA, Coxibs and Cardiovascular Disease, N Engl J Med 2004;351(17): 1709–1711. PMID 15470192.
  • Grassley CE (15 Oct 2004). Grassley questions Merck about communication with the FDA on Vioxx. Press Release.
  • Jüni P, Nartey L, Reichenbach S, Sterchi R, Dieppe PA, Egger M (2004). Risk of cardiovascular events and rofecoxib: cumulative meta-analysis. Lancet (published online; see also Merck response below)
  • Karha J and Topol EJ. The sad story of Vioxx, and what we should learn from it Cleve Clin J Med 2004; 71(12):933-939. PMID 15641522
  • Michaels, D. (June 2005) DOUBT Is Their Product, Scientific American, 292 (6).
  • Merck & Co., (5 Nov 2004). Response to Article by Juni et al. Published in The Lancet on Nov. 5. Press Release.
  • Merck & Co (30 Sep 2004) Merck Announces Voluntary Worldwide Withdrawal of VIOXX. Press release [7].
  • D. M. Mukherjee, S. E. Nissen, and E. J. Topol, “Risk of Cardiovascular Events Associated with Selective COX-2 Inhibitors,” Journal of the American Medical Association 186 (2001): 954–959.
  • Nussmeier NA, Whelton AA, Brown MT, Langford RM, Hoeft A, Parlow JL, et al. Complications of the COX-2 inhibitors parecoxib and valdecoxib after cardiac surgery. N Engl J Med 2005;352(11):1081-91. PMID 15713945
  • Okie, S (2005) “Raising the safety bar–the FDA’s coxib meeting.” N Engl J Med. 2005 Mar 31;352(13):1283-5. PMID 15800221.
  • Leleti Rajender Reddy, Corey EJ. Facile air oxidation of the conjugate base of rofecoxib (Vioxx), a possible contributor to chronic human toxicity Tetrahedron Lett 2005, 46: 927. doi:10.1016/j.tetlet.2004.12.055
  • Swan SK et al., Effect of Cyclooxygenase-2 Inhibition on Renal Function in Elderly Persons Receiving a Low-Salt Diet. Annals of Int Med 2000; 133:1–9
  • Targum, SL. (1 Feb. 2001) Review of cardiovascular safety database. FDA memorandum. [8]
  • Wolfe, MM et al., Gastrointestinal Toxicity of Nonsteroidal Anti-anflamattory Drugs, New England Journal of Medicine. 1999; 340; 1888-98.

External links

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4-methoxycinnamaldehyde spectral data for learners

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Jul 292014
 

4-Methoxycinnamaldehyde 

C10H10O2 
NMR Solvent: CDCl3

Note(s):
In the 13C NMR Spectrum, there are two nearly overlapping signals near 127 ppm which are indistinguishable at the initial magnification

 MASS

162.1852 MW

 

 

IR SPECTRUM

 

1H NMR

SPECTRUM

ChemicalStructure

 

 Assign.     Shift(ppm)
      A             9.651
      B             7.523
      C             7.422
      D             6.947
      E             6.610
      F             3.857

     J(A,E)=8.0HZ
     J(C,E)=15.7HZ

DEPT

 

13 C NMR

193.6  C=O

162.2

152.7

130.3

126.7

126.4

114.5

77.4

77.1

76.8

55.4  O-CH3

 

SPECTRUM

 

 

ChemicalStructure 
       ppm   Int.  Assign.
      193.41   257      1
      162.33   119      2
      152.42   259      3
      130.34   810      4
      126.98   139      5
      126.71   464      6
      114.68  1000      7
       55.47   414      8

 

 

 

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4-Ethoxybenzaldehyde NMR

 Uncategorized  Comments Off on 4-Ethoxybenzaldehyde NMR
Jul 282014
 

 

 

Example

C9H10O2

MW 150

Calculate the degree of unsaturation: the answer is 5. If the degree of unsaturation is 4 or greater, look for an aromatic ring, which has a degree of unsaturation of 4 (3 double bonds plus 1 ring). In addition to an aromatic ring, the molecule can have a carbon-carbon double bond, a carbonyl, or another ring.

IR Spectrum

Look for a carbonyl, since the degree of unsaturation indicates that the compound could have a double bond and we know that the molecule has an oxygen. There is a band at 1697, suggesting an alpha, beta unsaturated aldehyde or ketone(1710-1665). To see if the compound might be an aldehyde, look for bands in the region 2830-2695. In the spectrum below, note the two bands in this region, suggesting that the compound is indeed an aldehyde.

The IR can also help determine whether or not the compound is an aromatic (although the NMR is a better diagnostic method for this). Look for the C–H stretch in aromatics from 3100-3000. There are a couple very small bands in this region.

There is one more oxygen in the molecule, it could be an ether or even an ester (if we are incorrect in assuming an aldehyde is indicated). Ether IR bands are difficult to distinguish from any other C-O stretch band – the C-O stretch of alcohols, carboxylic acids, esters, and ethers all show up in the region 1320-1000 (see Ethers).

Consult the section on Aromatics for more information on IR spectroscopy of aromatics.

NMR Spectrum

From the IR, we know that compound is probably an aromatic and an aldehyde. Aldehydes and aromatics are quite distinctive in the NMR: aldehydes show up from 9-10, usually as a small singlet; aromatic protons show up from 6.5-8.5 ppm. Let’s look at the NMR:

 

The singlet at 9.9 ppm indicates an aldehyde; the 4 protons from 7-8 ppm indicate a di-substituted aromatic ring.

The remaining two peaks represent an ethyl group, -CH2CH3: 2 protons split by 3 protons adjacent to 3 protons split by 2 protons. The -CH2– portion of the ethyl group is shifted downfield further than the benzylic protons this indicates that it is next to an oxygen

Let’s draw an 8-carbon 10-hydrogen molecule incorporating these features: an aldehyde, a di-substituted aromatic ring, and an ethyl group:

The molecule is drawn as the para-substituted aromatic; this is indicated by the symmetry of the peaks in the aromatic region.

The following structure with the hydrogens in different colors shows how the protons correlate with the NMR peaks:

 

NOTE TWO AROM -H ORTHO TO O ATOM APPEAR AT 6.9 PPM

Summary

Example  is 4-ethoxybenzaldehyde:

 

 

13 C NMR OF 3-Ethoxy-4-methoxybenzaldehyde(1131-52-8)

Alittle complicated than above example

The interpretation is available in form of numbering

13CNMR

 

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3-BUTYL PYRIDINE, A simple nmr example

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Jul 272014
 

 

3 Butyl pyridine

Formula: C9H13N, 135.2062

IR 

IR spectrum

IH NMR

 

NMR spectrum

SEE

http://www.sigmaaldrich.com/spectra/fnmr/FNMR006274.PDF

 

 Unsaturation answer

C9H13N
Rule 3, omit the N and one H, gives C9H12
9 – 12/2 + 1 = 4 degrees of unsaturation.
Look for an aromatic ring.

IR interpretation

The bands at 3000-2850 indicate C-H alkane stretches. The band at 3028 indicates C-H aromatic stretch; aromatics also show bands in the regions 1600-1585 and 1500-1400 (C-C in-ring stretch), and 900-675 (C-H out-of-plane). The bands in the region 1250-1020 could be due to C-N stretch. The weak, broad banc at about 3500 could be amine N-H stretch or it could be a slight contamination of an impurity (water) in the sample.

 Structure answer

Structure answer
This is the structure. See if you can assign the peaks on your own.

NMR structure interpretation

NMR answer

 

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ETHYL PROPIONATE NMR, carbonyl is dad and oxygen mom, a methyl gets more attention

 Uncategorized  Comments Off on ETHYL PROPIONATE NMR, carbonyl is dad and oxygen mom, a methyl gets more attention
Jul 242014
 

Dedicated to all moms

C=O group is dad

 

O atom is mom

 

 

Carbonyl is dad and oxygen mom hence c labelled methyl has higher chemical shift  and gets a little more attention

SEE BELOW

NMR IS EASY

A chemical has Formula: C5H10O2

C5H10O2
Rule 2, omit O, gives C5H10
5 – 10/2 + 1 = 1 degree of unsaturation.
Look for 1 pi bond or aliphatic ring.

IR

IR spectrum

 

 

The band at 1740 indicates a carbonyl, probably a saturated aliphatic ester. The bands at 3000-2850 indicate C-H alkane stretches. The bands in the region 1320-1000 could be due to C-O stretch, consistent with an ester.

 

 

NMR spectrum

 Structure answer

Structure answerThis is the structure. See if you can assign the peaks on your own.

NMR answer

NMR answerC has a higher chemical shift than D because it’s closer to a more electron-withdrawing functional group.

Carbonyl is dad and oxygen mom,  hence c has higher chemical shift  and gets a little more attention in proton nmr

13 C NMR

Mass spectrum

 

RAMAN

 

 

 

WHAT HAPPENS WHEN A CHLORO IS INTRODUCED

 

 

 

WHEN THERE IS ONE METHYL

 

 

 

WHEN THERE ONE CH2 SHORT 

 

WHEN MOM HAS ONE MORE CH2

PROPYL PROPIONATE, try this on your own

Propyl propanoate.png

1H NMR

image of Propyl proprionate

 

 

image of Propyl proprionate

 

13C NMR

image of Propyl proprionate

 

APT

image of Propyl proprionate

 

COSY

image of Propyl proprionate

WILL PASTE INTERPRETATION AFTER ONE WEEK……………….

 

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