Atkuru Veera Venkata Naga Krishna Kumar - Department of Chemistry, NRI College
Tamanampudi Reddy - Department of Chemistry, Mallareddy College of engineering
Chandra Sekharan - Department of Pharmaceutical Biotechnology & Pharmaceutical analysis, Medarametla Anjamma Mastan Rao College of Pharmacy

Two new spectrophotometric methods (M۱ and M۲) are developed for the determination of vardenafil in bulk and in tablet dosage forms. The method M۱ involves oxidative coupling of vardenafil with ۳-methyl-۲-benzothiazolinone hydrazone hydrochloride in presence of ferric chloride in acidic medium yielding green colored chromogen with absorption maxima at ۶۲۵ nm. The method M۲ is based on the oxidation of ۴-aminoantipyrine by potassium periodate, which subsequently couples with vardenafil in an alkaline medium to form a red colored product having absorption maxima at ۵۳۰ nm. The absorbance concentration graphs were rectilinear over the range of ۴-۴۰ μg ml-۱ for the method M۱ and ۴-۶۰ μg ml-۱ for the method M۲. The limit of detection values was found to be ۰.۰۴۴ μg ml-۱ and ۰.۰۳۵ μg ml-۱ for the methods M۱ and M۲, respectively. The analytical performance of the developed methods was fully validated as per the guidelines prescribed by International Conference on Harmonization. The results were found to be acceptable. The application of the proposed methods in the determination of vardenafil in their commercial tablet dosage forms was successful showing good percentage recoveries.

Vardenafil, Electrophilic coupling agent, ۳-Methyl-۲-benzothiazolinone hydrazone, Aminoantipyrine, Analysis