Coadministration of buprenorphine (14-16 mg once daily, stable dose with naloxone) and tenofovir-DF (300 mg once daily) was studied in 10 opioid-dependent patients and values compared to 10 matched controls receiving tenofovir-DF alone. Coadministration had no significant effect on buprenorphine (AUC and Cmax increased by ~5% and ~9%, Cmin was unchanged) or its metabolites (norbuprenorphine AUC, Cmax and Cmin increased by ~7%, ~4% and ~1%, respectively; buprenorphine-3-glucuronide AUC and Cmin decreased by ~14% and ~9%, Cmax increased by ~9%; norbuprenorphine-3-glucuronide AUC increased by ~1%, Cmax decreased by ~3% and Cmin was unchanged). There was no effect on tenofovir disposition and concentrations of tenofovir remained in the therapeutic range during coadministration. The authors conclude that standard doses of tenofovir-DF may be safely given with standard buprenorphine/naloxone treatment.