Background Single-drug regimens (SDR) with ritonavir-boosted protease inhibitors (PI) could potentially be a regimen simplification to avoid nucleoside reverse transcriptase inhibitor (NRTI) toxicities in patients carrying human immunodeficiency virus (HIV) who fulfil several requirements: virological suppression, high level of medicines adherence, no previous IP virological failure and high CD4 count (>100 cell/mcL).

Purpose To evaluate the effectiveness and safety of SDR with ritonavir-boosted lopinavir (Lp/r) and ritonavir-boosted darunavir (Dr/r) in HIV-positive patients pre-treated with three-drug regimens (TDRs) including an NRTI.

Material and methods Retrospective observational study of HIV-positive patients with treatment switches from TDR to SDR in a second-level hospital.

Data were collected from the Farmatools-Dominion program and medical records. Variables included: sex, age, duration of previous TDR, plasma viral load (PVL) pre- and post-treatment switching, virological failure with PIs, CD4 cell count before switching and months of SDR to date (June’11–September’14).

Results Twenty-two patients were identified, 9 treated with Lp/r (5 men) and 13 with Dr/r (all men). Mean age at the time of the study: 48 + 6 years. 4 patients (2 with Lp/r and 2 with Dr/r) were co-infected with Hepatitis C virus and all subjects had been treated with TDR for a minimum of 12 months prior to treatment change. In all subjects basal PVL was undetected for at least 6 months before switching and remained undetectable during the entire study. One exception was a single patient with confirmed viral rebound which led to treatment re-intensification with two NRTIs included in the previous TDR.

No patients presented virological failure with the previous PI and the median CD4 counts at treatment switch were normal (825 ± 583 cell/mcL). All subjects were treated with SDR for a median period of 22 months and both adherence and tolerance were considered successful before and after switching.

Conclusion SDR with a ritonavir-boosted PI might be an alternative as effective as traditional combinations. It involves a clear benefit for HIV-positive patients because it simplifies treatment with minor toxicity and a small number of interactions.

References and/or acknowledgements No conflict of interest.