[Comparative hepatic toxicity of isoniazid, rifampicin and ethambutol]

Isoniazid, rifampicin and ethambutol administered in equimolecular dosages (50, 250 and 100 mg/kg, respectively) for 4 days caused liver affection. This was manifested by elevated activity of serum aminotransferases and alkaline phosphatase, inhibition of lipid peroxidation of hepatocyte membranes and antioxidative system dysfunctions. Isoniazid and rifampicin were proved to be most hepatotoxic. The combined use of antituberculous drugs increases their membrane-damaging action, especially when isoniazid and rifampicin are used together, but mostly when isoniazid in combination with rifampicin and ethambutol is applied.