FDA
New FDA‑approved 2‑drug option: once‑daily Idvynso for suppressed HIV
Brand name: Idvynso
Generic name: doravirine/islatravir
Manufacturer: Merck Sharp & Dohme LLC
Approval date: April 20, 2026
Idvynso (doravirine/islatravir) is an oral, once-daily combination of doravirine, a HIV-1 nonnucleoside reverse transcriptase inhibitor (NNRTI), and islatravir, a nucleoside analog reverse transcriptase inhibitor (NRTI). It's indicated as a complete regimen for the treatment of HIV-1 infection in adults to replace the current antiretroviral regimen in those who are virologically-suppressed (HIV-1 RNA <50 copies/mL) on a stable antiretroviral regimen with no history of virologic treatment failure and no known substitutions associated with resistance to doravirine.
“Idvynso is the first non-INSTI, tenofovir-free, two-drug regimen to demonstrate non-inferior efficacy to standard oral antiretroviral regimens, including Biktarvy. This makes Idvynso a potential alternative for people with virologically suppressed HIV who may need to switch their treatment,” said Dr. Amy Colson, director of research at Community Resource Initiative, Boston, Massachusetts.
Efficacy
The efficacy of Idvynso is supported by data from two randomized, active-controlled, non-inferiority trials (Trial 051 [NCT05631093] and Trial 052 [NCT05630755]) in virologically-suppressed adults living with HIV. Participants were stably suppressed on baseline therapy for at least 3 months, with no treatment failure history; active HBV infection was excluded.
In open‑label Trial 051, 551 participants were randomized 2:1 to switch to once‑daily Idvynso (n=366) or continue baseline antiretroviral therapy (n=185). At enrollment, 64% of the participants were receiving INSTI-based regimens, 5% PI-based regimens (including combinations with INSTI), and 30% other regimens.
In the double-blind Trial 052, 513 participants were randomized 2:1 to switch to once-daily Idvynso (n=342) or continue on bictegravir/emtricitabine/tenofovir alafenamide (Biktarvy) (n=171).
Idvynso was non-inferior to Biktarvy (in Trial 052) and baseline ART (in Trial 051). The primary endpoint for both studies was the proportion of participants with HIV-1 RNA ≥50 copies/mL at week 48. In Trial 052, 1% of participants who switched to Idvynso had a viral load of ≥50 copies/mL at week 48 vs. 1% who continued on Biktarvy (treatment difference 0.9%, 95% CI, -1.9%, 2.9%). In Trial 051, 1% of participants who switched to Idvynso had a viral load of ≥50 copies/mL at week 48 vs. 5% who continued on baseline ART (treatment difference -3.6%, 95% CI, -7.8%, -0.8%).
Safety
Most common adverse reactions (≥2%, all grades): diarrhea, dizziness, fatigue, abdominal distension, headache, and increased weight.
A single case of severe immune thrombocytopenia (platelet count nadir of 2 x109/L) characterized by abrupt onset of subcutaneous hematoma, petechiae, and hematuria was reported in a participant 32 days after initiating Idvynso in Trial 052. This serious adverse reaction resolved with discontinuation of the drug, in conjunction with treatments including corticosteroids and IVIG.
Severe skin reactions, including Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN), have been reported during postmarketing experience with doravirine-containing regimens. In addition, DRESS syndrome was reported with Idvynso in a clinical trial.
Idvynso is contraindicated when co-administered with other drugs that are strong CYP3A enzyme inducers, as well as lamivudine and emtricitabine.
Recommended dosing
One tablet taken orally once daily with or without food in adults.
Dosage adjustment with rifabutin: Take one tablet of Idvynso once daily, followed by one tablet of doravirine (Pifeltro) 100 mg approximately 12 hours after the dose of Idvynso.
Sources:
Merck. (2026, April 21). Press release. FDA Approves Merck’s Once-Daily Idvynso (doravirine/islatravir)
Idvynso (doravirine/islatravir). [Package insert]. Merck. https://www.merck.com/product/usa/pi_circulars/i/idvynso/idvynso_pi.pdf Revised April 2026. Accessed April 22, 2026.