Pharmacokinetics of triflusal and its main metabolite HTB in healthy subjects following a single oral dose.

The pharmacokinetic profile of triflusal (2-acetoxy-4-trifluoromethyl benzoic acid) and its main metabolite HTB (2-hydroxy-4-trifluoromethyl benzoic acid) has been studied in 8 healthy subjects (4 males and 4 females), after a single oral dose of 900 mg of triflusal. Plasma concentrations were determined by a sensitive HPLC method. Sampling was performed up to 120 h post medication. Triflusal displays a Cmax of 11.6 +/- 1.7 micrograms/ml and a tmax of 0.88 +/- 0.26 h. The elimination half-life (t1/2) was 0.55 h with a clearance (Cl/F) of 45.5 +/- 11.0 l/h. HTB kinetic parameters were: tmax 4.96 +/- 1.37 h and Cmax 92.7 +/- 17.1 micrograms/ml, with an elimination t1/2 of 34.3 +/- 5.3 and a clearance of 0.18 +/- 0.04 l/h. The results obtained in this study show a rapid absorption of triflusal and an immediate biotransformation into HTB. The long lasting platelet anti-aggregatory effect of triflusal in spite of its short t1/2, could be explained by the irreversible inhibition of platelet cyclo-oxygenase and the sustained levels of HTB, which also possess anti-aggregant properties.