Pharmacology: Pharmacodynamics: Ibuprofen lysine is the lysine salt of ibuprofen, a propionic acid derivative, having analgesic, anti-inflammatory and antipyretic activity. The therapeutic effects of ibuprofen lysine as a non steroidal anti-inflammatory drug are thought to result from inhibitory activity on prostaglandin synthesis.
Following oral administration, ibuprofen lysine dissociates to ibuprofen acid and lysine. Lysine has no recognized pharmacological activity. The pharmacological propeties of ibuprofen lysine, therefore, are the same as those of ibuprofen acid. Experimental data suggest that ibuprofen may inhibit the effect of low dose aspirin on platelet aggregation when they are dosed concomitantly. In one study, when a single dose of ibuprofen 400 mg was taken within 8 hours before or within 30 minutes after immediate release aspirin dosing (81 mg), a decreased effect of ASA on the formation of thromboxane or platelet aggregation occurred. However, the limitations of these data and the uncertainties regarding extrapolation of ex vivo data to the clinical situation imply that no firm conclusion can be made for regular ibuprofen use, and no relavant effect is considered to be likely for occasional ibuprofen use.
Pharmacokinetics: Most pharmacokinetic data obtained following the administration of ibuprofen acid also apply to ibuprofen lysine. Peak plasma concentrations occur 1-2 hours after administration of ibuprofen acid. However, ibuprofen is more rapidly absorbed from the gastrointestinal tract following the administration of Nurofen Express 342 mg and 684 mg Caplet, with peak plasma concentrations occurring approximately 35 minutes after administration in the fasting state.
The elimination half-life of ibuprofen acid is approximately 2 hours.
The drug is extensively bound to plasma proteins.
Ibuprofen is metabolized in the liver to two inactive metabolites and these, together with unchanged ibuprofen, are excreted by the kidney either as such or as conjugates. Excretion by the kidney is both rapid and complete. No specific difference in pharmacokinetic profile is observed in the elderly.