[01] Atkuru Veera Venkata Naga Krishna Sunil Kumar, Department of Chemistry, NRI Institute of Technology, Pothavarappadu, Andhra Pradesh, India. [02] Chandra Bala Sekaran, Department of Pharmaceutical Biotechnology and Pharmaceutical Analysis, Medarametla Anjamma Mastan Rao College of Pharmacy, Narasaraopet, Andhra Pradesh, India. [03] Tamanampudi Varahala Reddy, Department of Chemistry, Mallareddy College of Engineering, Secundrabad, Andhra Pradesh, India.

The purpose of the present investigation is to develop and validate three spectrophotometric methods (1, 2 & 3) for the determination of vardenafil (VDL). Method 1 is based on the oxidation of VDL with KMnO4 in 0.6 M NaOH at room temperature and measurement of the green colored manganate ions at 630 nm. Method 2 involves the formation of yellow colored chloroform extractable ion-pair complex of VDL with bromocresol green under acidic condition. The colored ion-pair complex is quantitated spectrophotometrically at 420 nm. Method 3 is based on the inner molecular complex formation of the VDL with acetaldehyde and sodium nitroprusside in alkaline medium. The colored inner molecular complex is measured at 560 nm. Under the optimized experimental conditions, the absorbance vs concentration plot was linear over the range of 10-100 µg/ml, 5-60 µg/ml and 2-20 µg/ml with molar absorptivities of 4.299 x 10³, 3.755 x 104 and 4.079 x 104 L/mole/cm for methods 1, 2 and 3, respectively. The limits of detection and quantification values were calculated to be 0.335 & 1.015 µg/ml (method 1), 0.055 & 0.166 µg/ml (method 2) and 0.013 & 0.039 µg/ml (method 3). The relative standard deviations obtained in the intra- and inter-day analyses were in the range of 0.082%-0.890% (method 1), 0.114%-1.515% (method 2) and 0.372%-0.942% (method 3). The methods are successfully applied to the quantification of VDL tablets with percentage recovery in the range of 99.30-99.88% (method 1), 99.60-99.88% (method 2) and 99.80-99.90% (method 3). Common excipients present in tablet formulations did not interfere with the assay. The results demonstrate that the proposed methods are accurate, reproducible and can be useful for routine analysis of VDL in tablets.

Vardenafil, Ion-Pair Complex, Oxidoreduction, Inner Molecular Complex, Spectrophotometric Analysis

[01] G. M. Keating and L. J. Scott, Vardenafil: A review of its use in erectile dysfunction, Drugs, 2003, 63, 2673-2703. [02] A. M. Morales, V. Mirone, J. Dean and P. Costa, Vardenafil for the treatment of erectile dysfunction: an overview of the clinical evidence, Clin. Interv. Aging, 2009, 4, 463-472. [03] I. Eardley, J. C. Lee, R. Shabsigh, J. Dean, M. Maggi, D. Neuser and C. Norenberg, Vardenafil improves erectile function in men with erectile dysfunction and associated underlying conditions, irrespective of the use of concomitant medications, J. Sex Med., 2010, 7, 244-255. [04] G. Manisha, P. Usha and P. Vandana, Development and validation of RP-HPLC method for estimation of vardenafil in bulk and pharmaceutical formulation. Am. J. Pharm Tech Res., 2013, 3, 928-938. [05] D. V. Subba Rao, K. V. Surendranath, P. Radhakrishnan, M. V. Suryanarayana and P. Raghuram, A stability indicating LC method for vardenafil HCl, Chromatographia, 2008, 68, 829-835. [06] Y. Di, M. Zhao, Y. Nie, F. Wang and J. Lv, A high-performance liquid chromatography: chemiluminescence method for potential determination of vardenafil in dietary supplement, J. Autom. Methods Manag. Chem., 2011, 2011, 1-6. [07] K. K. Kumar, C. K. Rao, Y. R.K. Reddy and K. Mukkanti, A validated rapid stability-indicating method for the determination of related substances in vardenafil hydrochloride by ultra-performance liquid chromatography, American J. Anal. Chem., 2012, 3, 59-66. [08] A. M. Idris and A. O. Alnajjar, Multi-Response optimization of a capillary electrophoretic method for determination of vardenafil in the bulk drug and in a tablet formulation, Acta Chromatogr., 2007, 19, 97-109. [09] J. R. Flores, J. J. B. Nevado, G. C. Penalvo and N.M. Diez, Development of a micellar electrokinetic capillary chromatography method for the determination of three drugs employed in the erectile dysfunction therapy, J. Chromatogr. B., 2004, 811, 231-236. [10] S.R. Gratz, C. L. Flurer and K. A. Wolnik, Analysis of undeclared synthetic phosphodiesterase-5 inhibitors in dietary supplements and herbal matrices by LC-ESI-MS and LC-UV, J. Pharm. Biomed. Anal., 2004, 36, 525-533. [11] International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use, ICH Harmonized Tripartite Guidelines, Validation of Analytical Procedures: Text and Methodology Q2 (R1), Current Step 4 version, Nov. 1996, Geneva, Nov. 2005. [12] D. Sukalyan, P. Sabita and K. M. Bijay, Oxidation by permanganate: synthetic and mechanistic aspects, Tetrahedron, 2009, 65, 707–739. [13] A. P. K. Aftab, M. Ayaz, B. Shaista, K. S. Siddiqi and M. A. Abdullah, Spectrophotometric methods for the determination of ampicillin by potassium permanganate and 1-chloro-2,4-dinitrobenzene in pharmaceutical preparations, Arabian J. Chem., 2015, 8, 255–263. [14] A. E. F. G. Ayman, E. S. Ragaa, E. S. Zeineb, H. Nagda and E. A. Rham, Spectrophotometric determination of pipazethate HCl and dextromethorphan HBr using potassium permanganate, Int. J. Biomed. Sci., 2008, 4, 294–302. [15] S. M. Fraihat and K. M. Bahgat, Spectrophotometric methods for the determination of ketoconazole in pharmaceutical dosage forms, Trop. J. Pharma. Res., 2014, 13, 1511-1514. [16] B.K. Jayanna, A facile spectrophotometric method for the determination of donepezil hydrochloride in tablets formulation using potassium permanganate, Asian J. Phar. Biol. Res., 2012, 2, 216-218. [17] T. Vetrichelvan, K. Arul, M. Sumithra and B. Umadevi, Colorimetric method for the estimation of escitalopram oxalate in tablet dosage form, Indian J. Pharm. Sci., 2012, 72, 269-271. [18] G. Balamma, N. S. M. Sagari, B. S. M., Kumar and P. J. Reddy, Spectrophotometric estimation of promethazine hydrochloride in bulk and pharmaceutical formulations, Int. J. Pharma. Res. Anal., 2012, 2, 6-8. [19] P. Ashwin, S. Alankar, J. Anurekha and G. K. Singh, Method development and validation for estimation of trihexyphenedyl hydrochloride in tablet dosage forms, Asian J. Res. Chem., 2009, 2, 104-107. [20] M. El-Adl Sobhy, M. E. Sadek, E. Hossinny and M. H. Hassan, Extractive spectro estimation of clarithromycin and clindamycin in bulk and dosage forms, Asian J. Res. Pharma. Sci., 2014, 4, 179-186. [21] C. F. Cullis and C. J. Waddington, The colorimetric determination of secondary amines, Anal. Chim. Acta, 1956, 15, 158–163. [22] S. K. Wolfe and J. H. Swinehart, Photochemistry of [22] pentacyanonitrosylferrate (2-), nitroprusside, Inorg. Chem., 1975, 14, 1049–1053. [23] B. M. Gurupadayya, M. N. Trinath and K. Shilpa, Spectrophotometric determination of meloxicam by sodium nitroprusside and 1,10-phenanthroline reagent in bulk and its pharmaceutical formulation, Indian J. Chem. Tech., 2013, 20, 111-115. [24] B. KalyanaRamu, Estimation of tianeptine in its tablet form using visible spectrophotometric methods, Asian J. Pharmaceu. Res. Health Care, 2013, 5, 72-79. [25] B. Kalyanaramu, K. Raghubabu and Y. Vamsikumar, Development of a simple colorimetric determination of ramipril from pharmaceutical formulations, J. Chem. Pharm. Res., 2011, 3, 863-869.