Comparative single-dose bioavailability study of two oral formulations of ibuprofen in healthy volunteers

Objective: To compare the bioavailability of equivalent doses of two oral formulations of ibuprofen: ibuprofen lysinate 1025mg (powder for oral suspension) and ibuprofen free acid 600mg (effervescent granules). Design and Setting: Nonblind, comparative, two-way, crossover, randomised design carried out in a phase I study unit. Participants: 24 healthy volunteers (10 males, 14 females) with mean age 23.42 years, mean bodyweight 65.38kg, mean height 170.75cm and mean body mass index 22.31 kg/m(2) Interventions: During each study period, a single oral dose of one of the formulations was administered, and 15 plasma samples were obtained to determine ibuprofen concentrations and calculate kinetic parameters. Results: The kinetic parameters [ibuprofen lysinate vs ibuprofen free acid (mean +/- SD)] were: area under the concentration-time curve from zero to infinity (AUC(0-infinity)) 181.64 +/- 64.84 vs 176.99 +/- 62.35 mg.h/L; maximum plasma concentration (C-max) 62.03 +/- 9.66 vs 51.39 +/- 12.84 mg/L; time to reach Cmax (t(max)) [median] 0.54 vs 1.75h. The 90% confidence intervals (CIs) of the ratios of logarithmically transformed values were 98.05 to 107.79% for AUC(0-infinity) and 112.87 to 137.07% for C-max; the 90% CI of the difference in t(max) was -1.5 to -1.0h. Conclusions: The extent of ibuprofen absorption is the same with both formulations. The speed of release/absorption is greater with the lysinate formulation. This is of particular significance for achieving a rapid analgesic or antipyretic.