Possible Interaction: Quinine and Rifampin

“ Rifampin should not be combined with quinine for the treatment of malaria, and the doses of quinine should probably be increased in patients who are already receiving rifampin treatment.”

“ Rifampin significantly increases the metabolic clearance of quinine and thereby reduces cure rates.”

“The mean elimination half-life of quinine when coadministered with rifampicin (5.5 +/- 3.0 h) was significantly shorter than when quinine was given alone (11.1 +/- 3.0 h; the 95% C.I. for the mean difference was -8.6 to -2.6).”

“The unbound clearance (CLu/F) of quinine, which reflects the …, was considerably greater (6.9-fold) in subjects when rifampicin … quinine than that of quinine alone (6.9 +/- 3.6 vs 1.0 +/- 0.5 …; the 95% C.I. for the mean difference was 3.3 to 8.5).”

“clearance (CL/F) of quinine coadministered with rifampicin (0.87 +/- 0.35 1 h-1 kg-1) was significantly greater than that of quinine alone (0.14 +/- 0.05 1 h-1 kg-1).”

“Quinine is mainly metabolized by the cytochrome P450 3A4 isozyme (CYP3A4), whereas rifampin , a potent inducer of CYP3A4, is known to markedly decrease plasma quinine concentration.”

“Our previous studies have shown that cigarette smoking and rifampicin pretreatment enhance the elimination of quinine , metabolism assumed, by analogy with quinidine, to be carried out by CYP3A (P450IIIA).”