Bioequivalence evaluation of two roxithromycin formulations in healthy human volunteers by high performance liquid cromatography coupled to tandem mass spectrometry.

The bioequivalence of two different formulations containing roxithromycin (SPE-712-1). Oral suspension 300 mg/15 mL as test formulation and Rotram, tablets 300 mg as reference formulation, both by Schering Plough S.A., Brazil) was evaluated in 24 healthy volunteers of both sexes (12 male and 12 female). The study was conducted open with randomized two-period crossover design and a 14-day washout period. Each subject received 300 mg of each roxithromycin formulation. Plasma samples were obtained over a 72-hour interval and roxithromycin concentrations were analyzed by combined LC-MS/MS with positive ion electrospray ionization using selected ion monitoring method. From the plasma roxithromycin concentration vs time curves the following pharmacokinetic parameters were obtained: AUC(0-72 h), AUC(0-infinity), Cmax, t1/2 ratios and tmax individual differences. The 90% for confidence interval (CI) of geometric mean SPE-712-L/Rotram individual percent ratio were 105.0-128.3% for AUC(0-72 h), and 78.4-96.9 for Cmax. Although this 90% CI were marginally outside the interval proposed by the Food and Drug Administration, the probability assessed by the two-one sided West for ratios was included in the 0.8-1.25 interval, as we concluded that SPE-712-L oral suspension formulation was bioequivalent to Rotram tablet formulation for the extent and rate of absorption.