Claudia Bernardini, Franco Maggiolo

The combination rilpivirine (RPV)/emtricitabine (FTC)/tenofovir (TDF) is a once-daily, single-tablet regimen (STR) containing one nonnucleoside reverse-transcriptase inhibitor associated with two nucleos(t)ide reverse transcriptase inhibitors. It is approved by regulatory agencies (eg, US Food and Drug Association, European Medicines Agency) in all countries in which it is manufactured, except Switzerland, as first-line highly active antiretroviral therapy (HAART) for the treatment of naïve patients with HIV infection and a viral load HIV-RNA level of ≤100,000 copies/mL. Two large trials (ECHO and THRIVE) comparing RPV with efavirenz, along with different background regimens, led to approval of the drug, while a more recent trial (STaR) explored the use of STR. RPV showed noninferiority to efavirenz in all the studies, including superiority as an STR in patients with HIV-RNA ≤100,000 copies/mL in the STaR study. A positive CD4 cell response was observed in all the studies, both in the RPV and efavirenz groups. The incidence of virologic failures was higher for RPV, but was mostly referred to patients with HIV-RNA >100,000 copies/mL. There were fewer adverse events (AEs) with the RPV-based regimens versus efavirenz-based regimens, with a lower discontinuation rate because of AEs, especially psychiatric-neurological AEs, and a significantly lower rate of blood-lipid abnormalities. In the SPIRIT study (a switch study), significantly greater improvements from baseline in serum total cholesterol, low-density lipoprotein cholesterol, and trygliceride were demonstrated in patients switching to RPV/FTC/TDF from a ritonavir-boosted protease inhibitor (PI/r)-based regimen, than in those who continued treatment with a PI/r regimen. RPV's better tolerability, associated with its once-daily STR formulation, is key to improving patients' adherence and quality of life, which are among the most important factors affecting the therapeutic efficacy of an antiretroviral regimen. In summary, RPV/FTC/TDF STR is a valuable treatment option for the majority of antiretroviral-naïve HIV-infected patients. Furthermore, the use of this STR in the therapeutic switch, like in the SPIRIT study, can result in another valuable option by which to reduce AEs and improve patients' quality of life.