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The FDA on April 20, 2026 approved Idvynso (doravirine and islatravir), Merck's once-daily two-drug tablet, for adults with HIV-1 who are virologically suppressed on a stable regimen and switching from it.
Doravirine is a non-nucleoside reverse transcriptase inhibitor Merck already sells alone as Pifeltro. Islatravir is a nucleoside analog reverse transcriptase inhibitor the company licensed from Yamasa Corporation of Japan in 2012. One tablet carries 100 mg of doravirine and 0.25 mg of islatravir.
Two switch trials read out at week 48. In Trial 052, 342 patients moved off bictegravir, emtricitabine and tenofovir alafenamide while 171 stayed on it, and 1% of each arm ended above 50 copies per mL. In Trial 051, 366 patients switched from their own regimens against 185 who did not, at 1% against 5%.
The label warns of severe skin reactions, including Stevens-Johnson syndrome and drug rash with eosinophilia, and directs immediate discontinuation.
The FDA placed islatravir on clinical hold in December 2021 after total lymphocyte and CD4 counts fell in trial participants. Merck cut the dose and restarted, and what emerged is a switch regimen for people already suppressed in the labeled population.
Sources: FDA prescribing information; Drugs@FDA, NDA 216964; Merck press release; Merck clinical hold announcement, December 2021; aidsmap on the 2021 holds; Fierce Pharma
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