Bioequivalence of tiopronin enteric capsules in healthy volunteers

OBJECTIVE: To evaluate the bioequivalence of tiopronin enteric capsules (testing preparation, T) versus tablets (reference preparation, R). METHODS: A single oral dose of tiopronin enteric capsules or tablets at 200 mg was administered in 2 groups of Chinese healthy volunteers (n=9) in a randomized crossover design at the interval of 2 weeks. The plasma concentrations of tiopronin were measured by HPLC-MS/MS, and the pharmacokinetic parameters were calculated by DAS 2.0 program. The bioequivalence between the two preparations was evaluated. RESULTS: The main pharmacokinetic parameters were as follows: C(max)(microg.ml(-1)) 3.612-/+1.2393 (R), 3.644-/+1.540 (T); t(max) 4.333-/+1.0853 (R), 3.611-/+1.420 (T); t((1/2))(h) 18.245-/+11.270 (R), 23.403-/+10.500 (T); AUC0-t (microg.h.ml(-1)) 18.732-/+6.92318 (R), 18.713-/+6.585 (T); AUC0-infinity (microg.h.ml(-1)) 21.900-/+7.31220 (R), 20.780-/+7.965 (T). The relative bioavailability of tiopronin enteric capsule was 103.712-/+23.956%, with 90% confidential intervals of ln(AUC0-->72), ln(AUC0-infinity) and ln(C(max)) of 91.1%-111.8%, 96.8%-118.3%, and 85.1%-113.0%, respectively. CONCLUSION: The tiopronin enteric capsules were bioequivalent to the tablets.