The pharmacokinetics of single and multiple doses of tiaprofenic acid in elderly patients with arthritis.

We have studied the single dose and steady-state pharmacokinetic of tiaprofenic acid in ten elderly arthritic patients living in the community (5 men and 5 women) taking 200 mg tid for 8 days. The mean area under the plasma concentration-time curves to 8 h (AUC (0-8)) did not alter significantly from day 1 to day 8 (77.25 to 79.61 micrograms X ml-1 X h). The mean terminal phase half-life (t1/2) was 2.05 h and 2.25 h on Days 1 and 8 respectively in patients in whom the calculations were possible (7 patients on Day 1 and 6 patients on Day 8). The median observed time of maximum concentration (tmax) and the mean observed maximum plasma concentration (Cmax) of 100 min and 21.3 micrograms X ml-1 respectively on Day 1 were not significantly different from the values obtained on Day 8 (tmax 120 min; Cmax 20.7 micrograms X ml-1). The kinetic data suggest that there should be no significant accumulation of tiaprofenic acid in elderly ambulant people suffering from arthritis.