Bioequivalence of two oral formulations of triflusal capsules in healthy volunteers

Triflusal (CAS 322-79-2) is an antiplatelet agent related to salicylates used in several European and Latin American countries in the treatment of cardiovascular diseases. The aim of this paper was to evaluate the bioequivalence of triflusal derived from two preparations using both parent drug and metabolite pharmacokinetic data. The bioavailability was measured in 24 healthy male Caucasian volunteers following a single oral dose (600 mg) of the test or reference products in the fasting state. Blood samples were collected for 120 h. Plasma concentrations of triflusal and its metabolite 3-hydroxy-4-trifluoromethylbenzoic acid (HTB) were analyzed by high-performance liquid chromatography with UV and fluorescence detection, respectively. The non-compartmental method was used for pharmacokinetic analysis. Log-transformed C-max, AUC(0-t) and AUC(0-infinity) were tested for bioequivalence using ANOVA and Schuirmann's two-one sided t-test. T-max was analyzed by nonparametric pharmacokinetic parameters of triflusal and HTB derived from the two formulations were nearly consistent with previous observations. Triflusal parameters derived from the test and reference drug were as follows: C-max (16.85 +/- 11.41 vs 14.48 +/- 7.22 mg/l), AUC(0-t) (18.43 +/- 10.91 vs 16.22 +/- 7.58 mg/l per hour), T-max (1 range 0.25-2 h vs 0.875 range 0.25-1.5 h), and t(1/2) (0.49 +/- 00.27 vs 0.76 +/- 0.64). HTB parameters after test and reference formulation administration were as follows: C-max (68.13 +/- 23.05 vs 65.51 +/- 19.44 mg/l), AUC(0-t) (2748.18 +/- 971.91 vs 2877.97 +/- 881.2 h . mg/l), AUC(0-infinity) (3350.15 +/- 1182.62 vs 3372.49 +/- 1110.35 h . mg/l), T-max (2 range 1-10 h vs 2 range 0.75-12 h), and t(1/2) (42.19 +/- 7.82 vs 43.13 +/- 6.36 h). 90% of confidence intervals for the test/reference ratio of C-max AUC(0-t) and AUC(0-infinity) derived from both triflusal and HTB were found within the range of 80%-125% acceptable for bioequivalence. No significant difference was found between the T-max values for triflusal and HTB. It was concluded that the two preparations are bioequivalent and may be prescribed interchangeably.