<p>Rifampicin may reduce effectivity of hormonal contraceptives, ACE inhibitors (e.g. enalapril, imidapril), antiemetics (e.g. aprepitant), antineoplastics (e.g. imatinib), diuretics (e.g. eplerenone), drugs for erectile dysfunction (e.g. tadalafil), oral hypoglycaemics (e.g. nateglinide, repaglinide), NSAIDs (e.g. etoricoxib). Rifampicin may reduce serum levels of atovaquone, ketoconazole. Antacids may reduce absorption of rifampicin. Anaesthetics and halothane may increase risk for hepatotoxicity with rifampicin and isoniazid.<br />
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Isoniazid may increase serum levels of phenytoin and theophylline; and may decrease carbamazepine metabolism. Stavudine may increase risk of distal sensory neuropathy with isoniazid. Antacids may reduce isoniazid absorption. May increase plasma levels of isoniazid with para-aminosalicylic acid. Increased risk of CNS toxicity when isoniazid is used concomitantly with cycloserine.<br />
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Pyrazinamide antagonizes the effects of probenecid and sulfinpyrazone.<br />
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Potentially Fatal: Concominant use with saquinavir/ritonavir may increase risk of severe hepatotoxicity. May reduce antiviral efficacy of atazanavir, darunavir, fosamprenavir, saquinavir, or tipranavir.</p>