Bio-analytical Method Development and Validation of Tadalafil with a Special Emphasis on Pharmacokinetic Study in Healthy Indian Subjects for the ODS Formulation

Background: Tadalafil is an oral drug that is used for treating erectile dysfunction (impotence) and pulmonary arterial hypertension. It relaxes muscles and increases blood flow to particular areas of the body. Objective: The present study was aimed to investigate the different pharmacokinetic parameters of the two different formulations of Tadalafil (CAS no. 171596-29-5), one is conventional tablet dosage formulation and other is ODS (Orally Disintegrating Strips) each of which contains 20 mg of tadalafil. Materials and Methods: A simple, rapid bio-analytical LC-MS/MS method with appropriate sensitivity, selectivity, accuracy and precision was developed and validated to quantify tadalafil in human plasma. Sildenafil was used as Internal Standards (IS). Electrospray ionization (ESI) MS–MS was used to analyze tadalafil. A high proportion of organic solvent Methanol: 10mM Ammonium Acetate in water (pH 6.38):: 9:1 (v/v) had been found best to coelute both substances with a flow rate of 0.5 mL/min using Phenomenex Gemini C18 coloumn (4.6 mmx50 mm, 5 µm). Results: The pharmacokinetic data of tadalafil in healthy human subjects of two different formulations show that the new ODS (Orally Disintegrating Strips) formulation is bioequivalent with the conventional tablet dosage formulation. Both the formulations were well tolerated with no observed adverse reactions.