No Interaction Expected
Emtricitabine/Tenofovir-DF (FTC/TDF, PrEP)
Quality of Evidence: Very Low
Coadministration of emtricitabine/tenofovir-DF and ethambutol alone has not been studied but based on metabolism and clearance a clinically significant interaction is unlikely. Ethambutol is partly metabolized by alcohol dehydrogenase (20%) and partly eliminated unchanged in the faeces (20%) and in the urine (50%). Coadministration of TB treatment containing ethambutol (with rifampicin, isoniazid and pyrazinamide) and emtricitabine/tenofovir-DF (with efavirenz) had no effect on ethambutol concentrations. Emtricitabine AUC and Cmin increased by 5% and 26% and Cmax decreased by 3%. Tenofovir AUC and Cmin increased by 13% and 9% and Cmax decreased by 2%.