Spectrophotometric Analysis of Vardenafil in Tablet Dosage Forms by Using Electrophilic Coupling Reagents

Two new spectrophotometric methods (M1 and M2) are developed for the determination of vardenafil in bulk and in tablet dosage forms. The method M1 involves oxidative coupling of vardenafil with 3-methyl-2-benzothiazolinone hydrazone hydrochloride in presence of ferric chloride in acidic medium yielding green colored chromogen with absorption maxima at 625 nm. The method M2 is based on the oxidation of 4-aminoantipyrine by potassium periodate, which subsequently couples with vardenafil in an alkaline medium to form a red colored product having absorption maxima at 530 nm. The absorbance concentration graphs were rectilinear over the range of 4-40 μg ml-1 for the method M1 and 4-60 μg ml-1 for the method M2. The limit of detection values was found to be 0.044 μg ml-1 and 0.035 μg ml-1 for the methods M1 and M2, 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.