Determination of Vardenafil in Pure and Dosage Forms by Spectrophotometry.

Three simple, sensitive, precise, and rapid spectrophotometric methods are developed and optimized for the assay of vardenafil in pharmaceutical formulations. The procedures are ascertained on the oxidation of vardenafil with a slight excess of N-bromosuccinimide (NBS), and the unreacted oxidant is estimated by evaluating the amount of the unconsumed NBS by reacting with a fixed amount of safranin (method A), crystal violet (method B), and aniline blue (method C) in an acidic medium by measuring the absorbance at 530, 600, and 610 nm, respectively. In all the methods, the amount of NBS consumed corresponds to the amount of the drug. Beer's law range, Sandell's sensitivity, and the corresponding molar absorptivity values of 1.1104 × 10⁴, 1.0305 × 10⁴, and 6.217 × 10³ L/mol × cm for methods A, B, and C are calculated. The limits of detection and quantification are evaluated. The methods are also evaluated statistically by means of Student's t-test and F-test. The results show excellent agreement and insignificant difference between the proposed methods and the reference method. The developed methods are successfully applied to the assay of Vardenafil in pure and dosage forms, and no interference is observed from common excipients present in pharmaceutical formulations. [ABSTRACT FROM AUTHOR]