Propafenone quantification in human plasma by high-performance liquid chromatography coupled with electrospray tandem mass spectrometry in a bioequivalence study

Propafenone is an antiarrhythmic drug applied to ventricular arrhythmias, initially recognized as a sodium channel blocker. This study aims to evaluate the bioequivalence of two propafenone formulations (300 mg tablet) in healthy subjects under non-fasting conditions. The study was conducted as an open, randomized, 2-period design with a 2-sequence (RT, TR) with a 1-week washout interval. The subjects were selected for the study after having their health status previously assessed by a clinical evaluation and laboratory tests (biochemical and hematological parameters, and urinalysis). Debrisoquine phenotype of healthy subjects was determined by analysis of urinary excretion of debrisoquine and its major metabolite, 4-hydroxydebrisoquine. A single propafenone tablet (300 mg) was given in each occasion. Plasma propafenone concentrations were analyzed by liquid chromatography coupled to tandem mass spectrometry (HPLC/MS/MS) with positive ion electrospray ionization using multiple reactions monitoring (MRM). The geometric mean and 90% confidence intervals (CI) of propafenone/Ritmonorm (R) (T/R) percent ratio were 100.44% (88.39 - 114.13%) for AUC(last) 9.84% (90.31 - 110.36%) for AUCmf(inf,)nd 99.30% (90.08 - 109.47%) for C-max. Since the 90% Cl Ior C-max, (A)UCla(st, a)nd AUCmf(inr)atios were all inside the 80 - 125% interval proposed by the US Food and Drug Administration Agency, it was concluded that the propafenone formulation elaborated by Biolab Sanus Farmaceutica Ltda. is bioequivalent to Ritmonorm* (R) ormulation for both the rate and the extent of absorption. The drug was well tolerated by the subjects, indicating that it is safe to perforrm propafenone bioequivalence studies in healthy subjects with intermediate/extensive metabolism.