Background. HIV protease inhibitors exhibit concentration-dependent viral inhibition. Higher once daily doses of darunavir boosted with ritonavir (DRV/r) may achieve viral suppression in place of twice daily dosing. International antiretroviral adherence guidelines recommend once daily regimens whenever possible. We present data on virologic suppression achieved with DRV 1,200？mg and ritonavir 100？mg once daily compared to approved DRV regimens. Methods. This retrospective observational study included all patients treated with DRV after documented use of another protease inhibitor at an urban immunodeficiency clinic. Data collection from inception of DRV use in August 2006 through March 2012 included patient demographics, viral loads, CD4+ cell counts, and resistance test results. The primary outcome of virologic suppression was defined as <50？copies/mL at 24 weeks. Differences in baseline characteristics and virologic outcomes across dosing groups were analyzed via one-way analysis of variance. Results. One hundred and thirty-five patients were included in the ITT analysis. Most patients had no known DRV RAMs at baseline. Virologic suppression rate was not different among treatment groups: 53.6% of patients on 1,200？mg daily, 52.3% on 600？mg twice daily, and 42.9% on 800？mg daily ( ). Conclusions. Darunavir 1,200？mg daily should be investigated for use in protease inhibitor-experienced patients. Darunavir 600？mg with 100？mg of ritonavir (DRV/r) dosed twice daily is currently approved in treatment-experienced patients as part of combination antiretroviral therapy (cART) which effectively suppresses HIV in this patient population [1]. DRV/r 800？mg daily is approved for patients lacking any DRV resistance associated mutations (RAMs), including treatment-na？ve patients [2]. DRV has a high genetic barrier to resistance enabling successful treatment even in the presence of multiple DRV RAMs [3]. The expansion of the antiretroviral armamentarium in recent years has led to ever more effective DRV/r-based cART against multiclass resistant HIV-1 [4, 5]. Treatment-experienced patients often have failed previous regimens due to poor adherence, adverse drug events, and the development of drug resistance. Therefore, the ideal regimen for treatment-experienced patients is well-tolerated, efficacious against drug-resistant virus, and convenient [6, 7]. Added emphasis has recently been placed on selecting once daily antiretroviral regimens for all patients to promote treatment adherence [7]. The regimen should suppress viremia below the lower limit of detection for the
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