Effects of isoniazid and pyrazinamide on bioavailability of rifampicin when co-administered rifampicin-isoniazid

The study was conducted to compare bioavailability of rifampicin at the same doses with and without isoniazid and pyrazinamide in the standard separate tablets in 12 healthy volunteers. Bioavailability of rifampicin was estimated by plasma concentration of rifampicin from 0h to 24h after administration. Plasma rifampicin concentration was determined by HPLC method. The results revealed that Cmax and AUC for rifampicin was reduced (31.24% and 25.95%, respectively) when rifampicin - isoniazid - pyrazinamide was administeredat the same time. It was concluded that bioavailability of rifampicin was affected by presence of isoniazid and pyrazinamide.

Study on the Bioavailability and Pharmacokinetics of Compound Rifampicin Tablets in Healthy Volunteers / 中国药房

OBJECTIVE:To study the pharmacokinetics and relative bioavailability of compound rifampicin tablets MET_HODS:Plasma levels of rifampicin(RFP),isoniazid(INH)and pyrazinamid(PZA) at different time were determined by HPLC methods,then we drew the time-concentration curves and got the pharmacokinetic parameters and relative bioavailability of test-tablets based on the curves RESULTS:The main pharmacokinetic parameters of RFP,INH and PZA in test-tablets were:Tmax,(1 69?0 60)h,(0 94?0 57)h and(2 36?1 10)h;Cmax,(9 86?2 09)?g/ml,(5 36?1 77)?g/ml and (16 20?4 85)?g/ml;T1/2,(3 43?0 72)h,(2 98?0 75)h and(9 26?1 58)h;AUC0～t,(59 34?13 17)?g/(ml?h),(21 87?14 29)?g/(ml?h) and(212 97?71 52)?g/(ml?h) respectively The main pharmacokinetic parameters of RFP,INH and PZA in control tablets were Tmax,(1 83?0 66)h,(0 86?0 38)h and (2 08?0 97)h;Cmax,(9 98?1 63)?g/ml,(5 60?2 01)?g/ml and (17 79?4 57)?g/ml;T1/2,(3 97?1 58)h,(3 15?0 88)h and (9 36?1 85)h;AUC0～t,(62 46?14 02)?g?h/ml,(21 39?14 53)?g/(ml?h) and (227 09?70 91)?g/(ml?h) respectively The relative bioavailability of test-tablets were (98 47?15 00)%,(103 76?15 80)% and (94 38?12 07)% CONCLUSION:The results of two one-sided tests and rank sum test showed that two formulae were statistically bioequivalent