FDA Approves Doravirine/Islatravir as Treatment for HIV

The FDA approved doravirine/islatravir (Idvynso) as a new 2-drug treatment of HIV for adults to replace their current antiretroviral regimen when virologically suppressed on a stable antiretroviral regimen with no history of virologic treatment failure. This approval introduces the first and only nonintegrase strand transfer inhibitor, a tenofovir-free, 2-drug complete regimen, to the market.¹

Consisting of 100 mg of the nonnucleoside reverse transcriptase inhibitor doravirine and 0.25 mg of the next-generation nucleoside analog reverse transcriptase inhibitor islatravir, the tablet is indicated specifically for patients who are stable on their current antiretroviral therapy with no history of treatment failure or known resistance to doravirine.

“Advances in HIV treatment mean more people living with HIV are living longer—a remarkable achievement,” Carl Baloney Jr, president and chief executive officer of AIDS United, said in a news release. “People aging with HIV face additional health challenges, including managing multiple chronic conditions and medications at the same time. It is essential that management of HIV considers these factors in addition to virologic suppression when choosing an HIV treatment regimen.”

Pharmacists should note that Idvynso will be available in pharmacies starting May 11, providing a new option for clinicians managing the evolving needs of adults living with HIV. The regimen’s unique pharmacological profile combines doravirine’s established safety with islatravir’s multiple mechanisms of action, which include translocation inhibition and delayed chain termination.

This dual-action approach was shown to be noninferior in efficacy to the 3-drug regimen Biktarvy in double-blind phase 3 trials. Specifically, in Trial 052, only 1% of participants who switched to Idvynso had a viral load of 50 copies/mL or greater at week 48, a result identical to those who remained on their baseline Biktarvy therapy.

The clinical development of the 0.25 mg islatravir dose used in Idvynso is particularly relevant to pharmacy practice, as earlier studies with higher doses faced challenges. A partial clinical hold was previously placed on higher doses of islatravir—such as the 0.75 mg dose evaluated in heavily treatment-experienced patients—due to observations of exposure-related decreases in CD4+ T-cell and total lymphocyte counts.²

Consequently, the approved 0.25 mg dose was selected based on modeling and phase 3 data to maintain efficacy while avoiding these lymphocyte decreases. Although Idvynso is highly effective for suppressed switch populations, it is not currently recommended for heavily treatment-experienced patients with multidrug resistance, as the lower islatravir dose may take several weeks to reach steady-state levels, potentially risking underdosing in those with high-level resistance.

From a safety and counseling perspective, Idvynso was generally well-tolerated in clinical trials, with a safety profile comparable to standard oral antiretroviral regimens. Unlike some older regimens, Idvynso was associated with minimal weight change from baseline. For instance, participants in Trial 052 saw a mean weight change of only -0.03 kg compared to a 0.28 kg increase in the Biktarvy group.¹

However, pharmacists must be vigilant regarding potential skin reactions, as severe cases of Stevens-Johnson syndrome, toxic epidermal necrolysis, and Drug Rash with Eosinophilia and Systemic Symptoms (DRESS) have been reported with doravirine-containing products. Additionally, a single case of severe immune thrombocytopenia was reported in clinical trials, though no broader pattern of platelet decrease was observed across the study population.

Idvynso is a complete regimen, and its co-administration with other antiretrovirals for the treatment of HIV-1 is not recommended. It is strictly contraindicated with strong cytochrome P450 (CYP)3A enzyme inducers, which can significantly decrease doravirine plasma concentrations and reduce efficacy. Furthermore, Idvynso should not be coadministered with lamivudine or emtricitabine because these drugs may decrease the active concentrations of islatravir-triphosphate. For patients requiring rifabutin, a dose adjustment involving an additional 100 mg tablet of doravirine taken 12 hours after the Idvynso dose is necessary. Pharmacists should also monitor patients with hepatitis B (HBV) coinfection closely when switching to this regimen, as Idvynso does not possess activity against HBV.¹

READ MORE: HIV Resource Center

Are you ready to elevate your pharmacy practice? Sign up today for our free Drug Topics newsletter and get the latest drug information, industry trends, and patient care tips straight to your inbox.

REFERENCES

1. FDA Approves Merck’s Once-Daily IDVYNSO (doravirine/islatravir). News release. Merck. April 21, 2026. Accessed April 21, 2026. https://www.merck.com/news/fda-approves-mercks-once-daily-idvynso-doravirine-islatravir/

2. Carr A, Mngqibisa R, Khaertynova I, et al. Efficacy and safety of doravirine/islatravir in heavily treatment-experienced participants living with HIV-1: results from a randomized trial. AIDS. 2026;40(2):189-197. doi:10.1097/QAD.0000000000004367