Determination of Vardenafil in Human Plasma by LC/MS/MS and its Clinical Applications

Abstract

Background: Sexual dysfunction as a result of the inability to achieve or maintain an erection is a common problem that increases with age. Vardenafil has shown results as an efficacious and safe therapeutic agent for treatment of erectile dysfunction. AIM: Development of a bio-analytical method for rapid quantification of vardenafil in biological fluids and its application in pharmacokinetics and bioavailability studies, clinical trials, and monitor its therapeutic levels to help attaining effective clinical results in treating erectile dysfunction. Methods: Vardenafil was extracted from plasma samples and chromatographed with eluting solvent consisting of 10mM Ammonium Acetate: Methanol (30:70) v/v at flow rate of 0.55ml/min, ESI positive mode, and m/z 489  151, 475  100 for vardenafil and sildenafil as internal standard respectively. As an application of the validated developed bioanalytical method, a comparative bioavailability study of vardenafil 20mg tablets generic product versus reference product was conducted in a randomized open label crossover design invovlving 24 volunteers. The criteria used to assess bioequivalence of the two products were Cmax, AUC 0-t, AUC 0-inf, and Tmax. Results: The average recovery of vardenafil from human plasma was 95.104 % with limit of quantitation of 0.05 ng/ml and the correlation coefficient (r2) obtained was 0.9998, moreover, statistical analysis (ANOVA) of the measured parameters showed that there was no significance between the two products. Conclusion: The developed bioanalytical LC/MS/MS method was valid for vardenafil quantification in human plasma and is suitable for application in pharmacokinetic studies and therapeutic monitoring of vardenafil in treating erectile dysfunction to ensure effective therapeutic drug levels and avoid potential undesired adverse events.