Ibuprofen and acetaminophen kinetics when taken concurrently.

We evaluated kinetics of ibuprofen and acetaminophen taken concurrently by 20 healthy adults in a randomized crossover design. Steady-state blood levels of ibuprofen and acetaminophen were measured by gas-liquid chromatography and HPLC. There were no significant differences in any of the ibuprofen serum concentrations, but there were differences in acetaminophen serum concentrations in 5 of 19 sampling times. When bioavailability and kinetic parameters for both drugs were compared, there were no significant differences. Our data demonstrate that steady-state kinetics of ibuprofen and acetaminophen are not changed when taken concurrently.