Predicting rapid analgesic onset of ibuprofen salts compared with ibuprofen acid: Tlag, Tlow, Tmed, and a novel parameter, TCmaxRef

AbstractObjective: This study evaluated the early absorption characteristics of ibuprofen salt formulations and standard ibuprofen acid (the reference).Methods: In this open-label, crossover, single-center study (NCT02452450) in 32 healthy, fasted adults receiving single oral doses (400 mg ibuprofen) of ibuprofen lysine, ibuprofen liquid capsule, ibuprofen sodium, ibuprofen acid, and paracetamol, intensive blood sampling was conducted for up to 6 h. Time between dosing and the start of absorption (Tlag); a novel parameter, time at which the test formulations (ibuprofen salts) reached the observed maximum plasma concentration (Cmax) of the reference (standard ibuprofen acid) (TCmaxRef); and time to achieve therapeutic plasma concentration were measured.Results: Ibuprofen was absorbed more rapidly from the salt formulations than the reference; Tlag was 3.3–6.4 min for salt formulations compared with 10.9 min for the reference, and 100% of subjects had a Tlag ≤ 5 min for ibuprofen lysine, compared with 61% f...