Comparative bioavailability of two once-daily tramadol HCl 200 mg extended-release products in healthy volunteers.

An open-label, randomized, 2-way crossover study was conducted to compare the pharmacokinetics of Tramadol Contramid OAD 200 mg tablets and Monocrixo L.P. 200 mg capsules following single-dose administration under fasting conditions in 30 healthy adult volunteers. Serial blood samples were collected at predefined time points over 48 hours post-dose and racemic tramadol and O-desmethyltramadol concentrations in plasma were determined using a validated LC-MS/MS method. Pharmacokinetic parameters were derived using noncompartmental methods. Results were compared using an analysis of variance (ANOVA) and the bioequivalence determination was based on the 90% confidence intervals for C(max), AUC(0-t) and AUC(0-infinity). Although the two products were determined to be bioequivalent with respect to C(max) and AUC, the time to reach peak tramadol concentrations was significantly earlier for Tramadol Contramid OAD (6 hours vs. 10 hours). A mean tramadol concentration of 100 ng/ml was attained within 1 hour for Tramadol Contramid OAD compared with > 4 hours for Monocrixo L.P. Both products were well tolerated.