According to a new announcement from Merck, the company has reached an agreement with the ADAP Crisis Task Force (ACTF) to help state AIDS Drug Assistance Programs (ADAPs) provide access to doravirine/islatravir (IDVYNSO; Merck), the company’s once-daily HIV-1 treatment.1 State ADAPs supported more than 250,000 people with HIV in the United States in 2024.
Doravirine/islatravir received FDA approval in April 2026 as a 2-drug single-tablet regimen combining 100 mg doravirine and 0.25 mg islatravir.1 The drug is indicated to replace a current antiretroviral regimen in adults who are virologically suppressed, defined as HIV-1 RNA below 50 copies per mL, on a stable regimen with no history of virologic treatment failure and no known doravirine resistance substitutions.2
ADAPs serve as a critical safety net for people with HIV who are uninsured or underinsured, and pharmaceutical agreements with the ACTF have historically determined pricing and access terms for state programs operating under constrained budgets. The agreement extends this access pathway to a recently approved single-tablet regimen, positioning state programs to offer IDVYNSO alongside existing covered therapies for eligible, virologically suppressed patients seeking to switch regimens.
READ MORE>> Lenacapavir and the Future of HIV Prevention: PURPOSE Trials, Long-Acting PrEP, and What Comes Next
“This agreement reflects our long-standing commitment to working with the ACTF, state ADAPs, and the HIV community to strengthen access and help address persistent gaps in care,” Conrod Kelly, US HIV business unit head at Merck, said in a statement.1
Frequently Asked Questions
What is doravirine/islatravir approved for?
Doravirine/islatravir (IDVYNSO; Merck) is approved as a once-daily, single-tablet regimen to replace a current antiretroviral regimen in adults with HIV-1 who are virologically suppressed on a stable regimen, with no history of virologic treatment failure and no known doravirine resistance substitutions.
How does doravirine/islatravir work?
IDVYNSO combines doravirine, an NNRTI that inhibits HIV-1 reverse transcriptase, with islatravir, an NRTI that blocks HIV-1 replication through reverse transcriptase translocation inhibition and induction of structural changes in viral DNA.
What does the ADAP Crisis Task Force agreement mean for access to doravirine/islatravir?
The agreement helps state AIDS Drug Assistance Programs add IDVYNSO to covered formularies, extending access to a recently approved switch regimen for uninsured and underinsured people with HIV who rely on ADAP coverage.
Doravirine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) that inhibits HIV-1 replication through noncompetitive inhibition of HIV-1 reverse transcriptase. Islatravir is a nucleoside analog reverse transcriptase inhibitor (NRTI) that blocks HIV-1 replication through 2 mechanisms: inhibition of reverse transcriptase translocation, producing immediate chain termination, and induction of structural changes in viral DNA, producing delayed chain termination.2
IDVYNSO safety profile and Merck’s broader HIV treatment pipeline
Doravirine/islatravir carries warnings for severe skin reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis, reported during postmarketing experience with doravirine-containing regimens, and drug rash with eosinophilia and systemic symptoms (DRESS syndrome), reported in a clinical trial.2 The most common adverse reactions occurring in 2% or more of participants across trials 051 and 052 were diarrhea, dizziness, fatigue, abdominal distension, headache, and weight increase.
A single case of severe immune thrombocytopenia, with a platelet count nadir of 2 x 10⁹/L, occurred in a participant 32 days after IDVYNSO initiation. The case resolved following discontinuation and treatment with corticosteroids and intravenous immunoglobulin. No patterns of platelet decline over time or treatment-arm differences in mean platelet count change were observed across trial participants.2
IDVYNSO is contraindicated with strong CYP3A enzyme inducers and with lamivudine or emtricitabine, since concurrent use with either nucleoside reverse transcriptase inhibitor may reduce islatravir-triphosphate concentrations and therapeutic effectiveness. The regimen is not recommended in patients with eGFR below 30 mL/min/1.73 m² or severe hepatic impairment and lacks activity against the hepatitis B virus, requiring close monitoring in patients with HBV coinfection.2
“ADAP programs play a critical role in supporting access to treatment for people living with HIV who are uninsured or underserved,” Tim Horn, director of medication access at the National Alliance of State and Territorial AIDS Directors, said in a statement.1
Merck’s HIV pipeline extends beyond IDVYNSO into multiple islatravir-based combinations. Islatravir paired with Gilead’s lenacapavir is in phase 3 development as a once-weekly oral regimen under the ISLEND-1 (NCT06630286) and ISLEND-2 (NCT06630299) trials, while islatravir combined with Merck’s investigational NNRTI ulonivirine is in phase 2b development. MK-8527, an investigational once-monthly oral PrEP candidate, is advancing through the phase 3 EXPrESSIVE-10 (NCT07071623) and EXPrESSIVE-11 (NCT07044297) trials in collaboration with the Gates Foundation.
References
Merck & Co., Inc. Merck Announces New Agreement with ADAP Crisis Task Force to Improve Access and Care for People Living with HIV. Published June 29, 2026. Accessed June 29, 2026. https://www.businesswire.com/news/home/20260629823507/en/Merck-Announces-New-Agreement-with-ADAP-Crisis-Task-Force-to-Improve-Access-and-Care-for-People-Living-with-HIV
IDVYNSO (doravirine and islatravir) Prescribing Information. Merck & Co., Inc. Accessed June 29, 2026. https://www.merck.com/product/usa/pi_circulars/i/idvynso/idvynso_pi.pdf
