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FDA approval · Merck · Infectious Disease

Idvynsodoravirine/islatravir

FDA approves a once-daily two-drug HIV-1 switch tablet without an INSTI or tenofovir.

CompareMerck press release
FDA approval · New moleculeOnly non-INSTI, tenofovir-free two-drug regimen55-second read

Idvynsodoravirine and islatravir

Merck · NNRTI plus NRTI (translocation inhibitor) two-drug regimen · Infectious Disease

Bottom line for your patients

Suppressed patients who need to switch have a complete two-drug daily tablet that contains no integrase inhibitor and no tenofovir. It is a switch option only, and patients with hepatitis B coinfection need separate monitoring and consideration of anti-HBV therapy.

Drug brief
Drug IQ
Who it is for
Adults with HIV-1 who are virologically suppressed (HIV-1 RNA less than 50 copies per mL) on a stable antiretroviral regimen, with no history of virologic treatment failure and no known substitutions associated with resistance to doravirine, to replace their current regimen.
What changes
Trial 052 compared switching to Idvynso with staying on Biktarvy (BIC/FTC/TAF), and Trial 051 compared switching with staying on baseline oral antiretroviral therapy. Merck describes it as the only two-drug, non-INSTI, tenofovir-free regimen.
The evidence
In Trial 052, 1% on Idvynso and 1% on BIC/FTC/TAF had HIV-1 RNA of 50 copies/mL or more at Week 48 (treatment difference 0.9%, 95% CI, -1.9%, 2.9%). In Trial 051, the figures were 1% on Idvynso and 5% on baseline ART.Head-to-head randomized trialTrial 052 (double-blind, vs Biktarvy, 513 participants) and Trial 051 (open-label, vs baseline ART, 551 participants) · Phase 3Randomized against an active treatment: the most direct evidence on how it compares with an existing option.
Watch for
Severe skin reactions, including Stevens-Johnson syndrome/toxic epidermal necrolysis, have been reported with doravirine-containing regimens, and DRESS was reported with Idvynso. A single case of severe immune thrombocytopenia was reported; the most common adverse reactions were diarrhea, dizziness, fatigue, abdominal distension, headache and increased weight.
How it is given
OralOnce-daily single tablet (100 mg doravirine and 0.25 mg islatravir)
What the approval tells you
New molecule. An active ingredient the FDA had not approved before.

Clinical summary

Idvynso is a single tablet of 100 mg doravirine and 0.25 mg islatravir for adults with virologically suppressed HIV-1 who are on a stable regimen with no history of virologic treatment failure and no known doravirine resistance substitutions. In the double-blind Trial 052, 1% of participants switched to Idvynso had HIV-1 RNA of 50 copies/mL or more at Week 48, compared to 1% who stayed on Biktarvy, meeting non-inferiority. It is contraindicated with strong CYP3A inducers and with lamivudine or emtricitabine, and it has no activity against hepatitis B virus.

From the source 13

Merck press release

The Merck press release's own words, quoted exactly. Each line is what a claim on this page was checked against.

  1. Merck (NYSE: MRK), known as MSD outside of the United States and Canada, announced today that the U.S. Food and Drug Administration (FDA) approved IDVYNSO™, a new, two-drug single-tablet regimen of 100 mg doravirine and 0.25 mg islatravir, for the treatment of HIV-1 infection in adults to replace the current antiretroviral regimen in those who are virologically suppressed (HIV-1 RNA less than 50 copies per mL) on a stable antiretroviral regimen with no history of virologic treatment failure and no known substitutions associated with resistance to doravirine.

    Backs · 100 mg doravirine and 0.25 mg islatravir; approved population; less than 50 copies per mL

  2. IDVYNSO is the first and only non-INSTI, tenofovir-free, once-daily, complete two-drug regimen to demonstrate non-inferior efficacy in a head-to-head Phase 3 trial versus three-drug regimen BIKTARVY®i (BIC/FTC/TAF)

    Backs · First and only non-INSTI, tenofovir-free, once-daily two-drug regimen; head-to-head Phase 3

  3. IDVYNSO is contraindicated when co-administered with drugs that are strong cytochrome P450 (CYP)3A enzyme inducers and lamivudine (3TC) or emtricitabine (FTC).

    Backs · Contraindications

View all 13 lines

  1. A total of 513 participants were randomized (2:1) and were switched to once-daily IDVYNSO (n=342) or remained on BIC/FTC/TAF (n=171).

    Backs · Trial 052 enrolled 513 participants

  2. In the double-blind Trial 052, results for the primary endpoint (HIV-1 RNA ≥50 copies/mL) showed that 1% of participants who were switched to IDVYNSO (n=342) had a viral load of ≥50 copies/mL at Week 48, compared to 1% who continued on BIC/FTC/TAF (n=171; treatment difference 0.9%, 95% CI, -1.9%, 2.9%).

    Backs · Trial 052 result: 1% vs 1%, difference 0.9%, Week 48

  3. In the open-label Trial 051, results for the primary endpoint (HIV-1 RNA ≥50 copies/mL) showed that 1% of participants who were switched to IDVYNSO (n=366) had a viral load of ≥50 copies/mL at Week 48, compared to 5% who continued on bART (n=185; treatment difference -3.6%, 95% CI, -7.8%, -0.8%).

    Backs · Trial 051 result: 1% vs 5%

  4. IDVYNSO was non-inferior to BIC/FTC/TAF (in Trial 052) and bART (in Trial 051) as assessed by the proportion of participants with HIV-1 RNA ≥50 copies/mL at Week 48.

    Backs · Non-inferiority in both trials

  5. As the only two-drug, non-INSTI, tenofovir-free regimen, IDVYNSO expands therapeutic diversity beyond the currently available oral treatment options,

    Backs · Only two-drug, non-INSTI, tenofovir-free regimen; NNRTI and NRTI classes

  6. IDVYNSO does not have activity against hepatitis B virus (HBV).

    Backs · No HBV activity

  7. Severe skin reactions, including Stevens-Johnson syndrome/toxic epidermal necrolysis, have been reported with doravirine-containing regimens. Drug Rash with Eosinophilia and Systemic Symptoms was reported with IDVYNSO.

    Backs · Skin reactions

  8. 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.

    Backs · Single case of severe immune thrombocytopenia

  9. The most common adverse reactions (incidence ≥ 2%, all grades in any treatment group) reported in virologically suppressed participants in the IDVYNSO treatment groups from 2 clinical trials, respectively, were: diarrhea (3% and 1%), dizziness (2% and 1%), fatigue (2% and 1%), abdominal distension (2% and 1%), headache (2% and 1%) and increased weight (2% and <1%).

    Backs · Most common adverse reactions

  10. Idvynso | doravirine and islatravir | 4/20/2026

    Backs · FDA action date 2026-04-20 (from FDA Novel Drug Approvals for 2026 table, https://www.fda.gov/drugs/novel-drug-approvals-fda/novel-drug-approvals-2026; the Merck release is dated April 21, 2026)

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