Pharmacokinetics of triflusal after single and repeated doses in man.

Triflusal pharmacokinetics were evaluated in 8 healthy subjects after a single 300 mg dose and after repeated doses of 300 mg every 8 h and 600 mg every 24 h during 13 days, with the aim of establishing a relationship between plasma levels and dosage patterns. Plasma concentrations of triflusal and its main metabolite, 2-hydroxi-4-trifluoromethylbenzoic acid (HTB), were determined by HPLC. Triflusal (t1/2 = 29-35 min) metabolized rapidly into HTB. Four h after the first or last repeated dose administration, triflusal levels could not be detected. After the administration of 300 mg every 8 h, the parameters obtained for HTB were: Cmax-ss = 178 +/- 42 micrograms/ml, tmax-ss = 1.9 +/- 0.7 h, Cmin-ss = 155.6 +/- 41.2 micrograms/ml, Cavg-ss = 168.0 +/- 41.8 micrograms/ml and a t1/2 of 48 +/- 15 h. The parameters obtained for the dosage of 600 mg every 24 h were: Cmax-ss = 153 +/- 40 micrograms/ml, tmax-ss = 2.7 +/- 0.9 h, and a t1/2 of 50 +/- 16 h. No significant differences were observed between the elimination half-life obtained after the single dose and after the two repeated dose regimens studied. This finding suggests that HTB displays a linear pharmacokinetic behaviour.