No Interaction Expected
Quality of Evidence: Very Low
Coadministration of tenofovir-DF and isoniazid alone has not been studied but based on metabolism and clearance, a clinically significant interaction is unlikely. Isoniazid is acetylated in the liver to form acetylisoniazid which is then hydrolysed to isonicotinic acid and acetylhydrazine. Coadministration of TB treatment containing isoniazid (with rifampicin, ethambutol and pyrazinamide) and tenofovir-DF (with emtricitabine and efavirenz) increased tenofovir AUC and Cmin by 13% and 9% and decreased Cmax by 2%; isoniazid Cmax decreased by 5%.