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Tadalafil

INTRODUCTION Tadalafil is a potent and selective phosphodiesterase-5 (PDE-5) inhibitor, asecondary messenger for the smoothmuscle relaxing effects of nitric oxide,which plays an important role in thevasodilation of erectile tissues.1-3 OralPDE-5 inhibitors have become the preferredfirst-line treatment for erectile dysfunction worldwide.4

PREPARATION

  Stereoselective synthesis of (+)-tadalafil (1) and(+)-6-epi-tadalafil (8)[20]The target isomeric tadalafil molecule is shown . Thus,D-tryptophan methyl ester reacted with piperonal3under Pictet–Spen-gler reaction condition (TFA/CH2Cl2/MeOH) to furnish two diastereo-mers4and6in 25% and 24% yields, respectively. Condensation of4or6with chloroacetyl chloride provided acylated intermediate 5or7in almostquantitative yield. Subsequent cyclization of5withN-methyl amine inmethanol at 50C for 16 h provided diastereomers tadalafil (1) in 54%yield. Compound1is in full accordance with the literature data {[a]D20¼+71.4 (c 1.00, CHCl3); lit. [a]D20¼+71.2 (c 1.00, CHCl3)}[17,18]. Thus,under the elongated reaction time, 48 h, compound8was obtained fromprecursor7with decreased yield of 21%

SECTION 1         SECTION 2     .. SECTION 3 Journal of Pharmaceutical and Biomedical Analysis 47 (2008) 103–113 Analysis of illegally manufactured formulations of tadalafil (Cialis®) by 1H NMR, 2D DOSY 1H NMR and Raman spectroscopy Saleh Trefia, Corinne Routaboul b, Saleh Hamieh a, Veronique Gilard ´ a, Myriam Malet-Martino a,∗, Robert Martino a a Groupe de RMN Biom´edicale, Laboratoire SPCMIB (UMR CNRS 5068), France b Service commun de spectroscopie IR et Raman, Universit´e Paul Sa LC-DAD apparatus and chromatographic conditions HPLC was carried out using a Waters 2695 Alliance model with a Waters 2996 diode array detector. The analytical column was a reversed-phase column Luna C18 (100 mm × 3 mm i.d.; 3m particle size; Phenomenex, UK). The column temperature was 30 ◦C. The mobile phase consisted of a mixture (35:65, v/v) of acetonitrile and phosphate buffer (10 mmol L−1, pH 3). The flow rate was 0.6 mL min−1 and the volume injected 10 L. A detection wavelength of 225 nm was chosen as it allows the detection of all tadalafil or sildenafil analogues. For quantitative analysis, a calibration curve was constructed from the analysis of four solutions containing pure tadalafil in a concentration range of 0.01–0.1 mg mL−1. Each standard solution was injected in triplicate in the chromatographic system. The linearity (R2 > 0.999) was evaluated by least-squares linear regression analysis. LC–MS analysis The HPLC system used consisted of an Agilent 1100 series apparatus. An Applied System QTRAP triple quadrupole mass spectrometer, equipped with a turbo ion spray (TIS) interface, was used for detection. Both were controlled by an Agilent Analyst software (version 1.4). HPLC conditions were as follows. The column temperature was 30 ◦C. The mobile phase consisted of a mixture (50:50, v/v) of acetonitrile and a buffer solution (ammonium acetate 10 mmol L−1, pH 7). The flow rate was 0.6 mL min−1 and the volume injected 5 L. The mass spectrometer was operated in positive ionisation mode with TIS heater set at 450 ◦C. Nitrogen served both as auxiliary, collision gas and nebuliser gas. The operating conditions for TIS interface were—(i) in MS mode: mass range 200–550m (1 s), step size 0.1m; Q1 TIS MS spectra were recorded in profile mode, IS 5000 V, DP 85 V; (ii) in MS–MS mode: precursor mass 489 m; mass range 10–500 m (0.35 s); step size 0.15m; LC–MS–MS spectra were rec d in profile mode, IS 5000 V, DP 85 V and CE 40 V   Fig. 3. DOSY NMR spectra in CD3CN:D2O (80:20) of genuine Eli Lilly Cialis® (A), formulation 6   Fig. 2. Raman spectra of pure tadalafil (A) and genuine Eli Lilly Cialis®: whole tablet (B), uncoated tablet from 200 to 1800 cm−1 (C), from 2500 to 3200 cm−1 (D). TiO2; talc (as shoulders of TiO2 bands); () lactose; () sodium lauryl sulfate; () magnesium stearate; (T) tadalafil.   ……………   Instrumentation The HPLC system consisted of a 1100 series quaternary pump, degasser, automatic injector, thermostatted column compartment, and diode array detector (Agilent Technologies, Palo Alto, CA);Vortex TecnoKartell TK3; shaker BIOSAN Multi Bio RS-24, and innovative mixing cycle (VWR international, USA).The data were collected using the system software (Chemstation 1990- 2002, Agilent Technologies). Chromatographic Conditions The separation was achieved on an Agilent LiChrospher 100, C18 column, 5-μm particle size, 250 x 4 mm I.D., with a 2-μm precolumn filter.The mobile phase consisted of 65% water acidified with glacial acetic acid (0.1 mM, pH 2.5- 2.7) and 35% acetonitrile. The flow rate was 0.8 mL/min, and UV detection was performed at 280 nm. All analyses were made at room temperature. The injection volume was 25 μL, and a small volume of air was bubbled through each sample before injection.   pg 171-175

…………………………………… Research In Pharmaceutical Biotechnology Vol. 2(1), pp. 001-006, February, 2010 Available online at http://www.academicjournals.org/RPB Validation and stability indicating RP-HPLC method for the determination of tadalafil API in pharmaceutical formulations B. Prasanna Reddy1*, K. Amarnadh Reddy2 and M. S. Reddy3 1Department of Quality control, Nosch Labs Pvt Ltd, Hyderabad-500072, A.P, India. 2 Department of AR and D, Aurigene Discovery Technologies Ltd, Bangalore, India. 3Department of Plant Pathology and Entomology, Auburn University, USA.

Battu.Prasanna Reddy Ph.D

The present study describes the development and subsequent of a stability indicating RP-HPLC method for the analysis of tadalafil. The samples separated on an Inertsil C18, (5 m , 150 mm x 4.6 mm i.d) by isocratic run using acetonitrile and phosphate buffer as mobile phase), with a flow rate of 0.8 ml/min, and the determination wavelength was 260 nm for analysis of tadalafil. The described method was linear within range of 70 – 130 μg/ml (r2 = 0.999). The precision, ruggedness and robustness values were also within the prescribed limits (< 1% for system precision and < 2% for other parameters). Tadalafil was exposed to acidic, basic, oxidative and thermal stress conditions and the stressed samples were analyzed by the proposed method. Chromatographic peak purity results indicated the absence of coeluting peaks with the main peak of tadalafil, which demonstrated the specificity of assay method for estimation of tadalafil in presence of degradation products. The proposed method can be used for routine analysis of tadalafil in quality control laboratories. Tadalafil hydro-2-methyl-6-[3,4-(methylenedioxy)phenyl]pyrazino-[1’,2’:1,6]pyrido[3,4-b]indole-1,4-dione (Figure1), is a phosphodiesterase type 5 inhibitor used in the management of erectile dysfunction. It is not officially included in any of the pharmacopoeias. It is listed in the Merck Index (Budavari et al., 2001) and Martindle and complete drug reference (Sean et al., 2002). There are several (Cheng et al., 2005) methods for determination of tadalafil such as HPLC-EIMS (Zhu et al., 2005) and capillary electrophoresis methods (Aboul-Enein, 2005) and by HPLC (Aboul, 1994). The present work was designed to develop a simple, precise and rapid analytical LC procedure, which would serve as stability indicating assay method for analysis of tadalafil active pharmaceutical ingredient. *Corresponding author. E-mail: drbpkreddy@gmail.com. Tel: +91-9848392677. Prasanna Reddy. Manager, Quality Control, Nosch Labs Pvt Ltd. Hyderabad, INDIA  http://bloggerbattu.blogspot.in/   REFERENCES 1. Pomerol JM, Rabasseda X.Tadalafil, a furtherinnovation in the treatment of sexual dysfunction. Drugs Today (Barc). 2003;39:103-113. 2. Francis SH, Corbin JD. Molecular mechanismsand pharmacokinetics of phosphodiesterase-5 antagonists. Curr Urol Rep. 2003;4:457-465. 3. Seftel AD. Phosphodiesterase type 5 inhibitordifferentiation based on selectivity, pharmacokinetic,and efficacy profile. Clin Cardiol.2004;27(4 suppl 1):I14-I19. 4 Bella AJ, Brock GB.Tadalafil in the treatment of erectile dysfunction. Curr Urol Rep. 2003;4:472-478. 7A. Daugan, P. Grondin, C. Ruault, A.-C. Le Monnier de Gouville, H. Coste, J. Kirilovsky,F. Hyafil, R. Labaudinie

[9] M.W. Orme, J.C. Sawyer, L.M. Schultze, World Patent WO 02/036593 17 S. Xiao-Xin, L. Shi-Ling, X. Wei, X. Yu-Lan, Tetrahedron Asymmetr. 19 (2008) 435.

Tadalafil

Systematic (IUPAC) name
(6R–trans)-6-(1,3-benzodioxol-5-yl)- 2,3,6,7,12,12a-hexahydro-2-methyl-pyrazino [1′, 2′:1,6] pyrido[3,4-b]indole-1,4-dione
Clinical data
Trade names	Cialis
AHFS/Drugs.com	monograph
MedlinePlus	a604008
Pregnancy category	B
Legal status	℞ Prescription only
Routes	Oral
Pharmacokinetic data
Bioavailability	varies
Protein binding	94%
Metabolism	CYP3A4 (liver)
Half-life	17.5 hours
Excretion	feces (> 60%), urine (> 30%)
Identifiers
CAS number	171596-29-5
ATC code	G04BE08
PubChem	CID 110635
DrugBank	DB00820
ChemSpider	99301
UNII	742SXX0ICT
KEGG	D02008
ChEBI	CHEBI:71940
ChEMBL	CHEMBL779
PDB ligand ID	CIA (PDBe, RCSB PDB)
Chemical data
Formula	C22H19N3O4
Molecular mass	389.404 g/mol