The durability of virological success of tenofovir and didanosine dosed at either 400 or 250 mg once daily.

Tenofovir (TDF) co-administered with didanosine (ddI) 400 mg increases ddI plasma concentrations by up to 60%, raising concerns over toxicity. To limit this interaction, the dosage of ddI may be reduced to 250 mg once daily when co-prescribed with TDF. In this clinical cohort, highly active antiretroviral therapy regimens containing TDF and ddI 250 mg were significantly better tolerated than combinations with TDF and ddI at a dose of 400 mg. Low-dose ddI 250 mg once daily plus TDF as part of antiretroviral therapy was effective.