Effects of rifampin and isoniazid on the isolated perfused rat liver

The effect of the antitubercular drugs rifampin and isoniazid on the function of the isolated, perfused rat liver was evaluated by monitoring the rate of bile flow and sulfobromophthalein (BSP) clearance. The effect of rifampin on bile flow was biphasic: rifampin concentration of 100 micrograms/ml increased the flow to 134% of baseline, while 1,000 micrograms/ml decreased the flow to 58% of baseline (p less than 0.01 for both). Rifampin also caused a dose-dependent inhibition of BSP removal from the perfusate and excretion in the bile. Isoniazid had no adverse effect on bile flow and BSP clearance, and the combination of isoniazid and rifampin had the same effects on the perfused liver as rifampin alone.