Once-daily single-tablet regimens: a long and winding road to excellence in antiretroviral treatment.

Once-daily single-tablet regimens represent the paramount simplification of antiretroviral treatment achieved so far. They include drugs with favorable pharmacokinetics that allow once-daily administration, that do not need dose adjustments, have no additional toxicities, and do not require dissimilar intake conditions. Co-formulated efavirenz/tenofovir disoproxil fumarate/emtricitabine has been a gold standard of initial therapy since its approval in 2006. Galenic research and industry patent agreements may allow availability of single-tablet regimens with HIV-1 nonnucleoside reverse transcriptase inhibitors (efavirenz or rilpivirine), integrase inhibitors (cobicistat-boosted elvitegravir or dolutegravir), and protease inhibitors (cobicistat-boosted darunavir), combined with either tenofovir disoproxil fumarate/emtricitabine or abacavir/lamivudine. The introduction of the new phamacoenhancer cobicistat as a potential substitution for ritonavir and the investigational agent GS-7340, with one-tenth the tenofovir mass, is a breakthrough in antiretroviral drug development. Many HIV-1-infected patients who are treatment-naive or treatment-experienced with susceptible virus will potentially have more options to reduce pill burden and optimize dosage schedules with one pill once-daily regimens.