Switching from Efavirenz to Rilpivirine
January 2, 2012
It has been reported previously that efavirenz reduces serum levels of rilpivirine and that this effect may be prolonged, even after discontinuation of efavirenz (see Sustained Effect of Efavirenz on Rilpivirine Serum Concentrations). A small, nonrandomized study was designed to answer the question of whether it is possible to switch directly from efavirenz to rilpivirine without loss of virologic control.
Forty-nine subjects who complained of adverse effects on efavirenz/tenofovir/emtricitabine (Atripla) were changed to rilpivirine/tenofovir/emtricitabine (Complera). Subjects were on their first antiretroviral regimen with virologic suppression for ≥3 months (most had >1 year of suppressed HIV RNA), and had no baseline reverse transcriptase (RT) mutations. Twelve weeks after the switch, all subjects maintained HIV RNA levels of <50 copies/mL (that was the primary end point). Pharmacokinetic analysis showed that rilpivirine trough levels were suppressed initially but, within 2-4 weeks had risen to the levels that were seen in the Phase 3 studies of rilpivirine, whereas efavirenz levels remained in therapeutic range for several weeks after discontinuation.
Clinical bottom line
This small study provides some reassurance that switching directly from efavirenz to rilpivirine may be a successful treatment strategy, at least for the specific group of patients who have wild-type HIV and have long-term virologic control on efavirenz-based ART. For other patients, including those who have detectable viremia on efavirenz (eg, during the early weeks of ART) and those who have been virologically suppressed for only a short time, these results may not be applicable. Optimal strategies for managing the interaction between efavirenz and rilpivirine have yet to be identified, and if direct switches are made from efavirenz to rilpivirine, they should be made with caution.
- Mills A, Cohen C, Dejesus E, et al. Switching from efavirenz/emtricitabine/tenofovir disoproxil fumarate (EFV/FTC/TDF) single tablet regimen (STR) to emtricitabine/rilpivirine/tenofovir disoproxil fumarate (FTC/RPV/TDF) STR in virologically suppressed, HIV-1 infected subjects. In: Program and abstracts of the 51st Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC); September 17-20, 2011; Chicago. Abstract H2-794c.
Susa Coffey is medical editor of the NCRC. She is a Professor of Medicine at UCSF in the Division of HIV, Infectious Diseases and Global Medicine and a longtime clinician and educator in the HIV at San Francisco General Hospital clinic (“Ward 86”). She also is medical editor of HIV InSite.