What Is Idvynso, and Why Does It Matter?
Idvynso (doravirine/islatravir) is a fixed-dose combination of two prescription medicines and is taken as a single, once-daily pill to treat HIV type 1 (HIV-1) infection in adults. Idvynso is recommended for patients who have very low levels of the virus, who don’t have a history of treatment failure, and in whom HIV-1 has not undergone any changes that would make doravirine less effective.
HIV‑1 is the most common type of HIV. If left untreated, the infection gradually weakens the body’s immune system. The most advanced stage of HIV is called AIDS, a condition in which the body becomes highly vulnerable to serious infections and certain cancers.
The Idvynso tablet is a combination of two medicines: doravirine and islatravir. Doravirine is a non-nucleoside reverse transcriptase inhibitor that blocks the reverse transcriptase enzyme, which HIV needs to make copies of itself. Islatravir is a next-generation medicine that prevents the virus from multiplying via various mechanisms — by preventing HIV from building new genetic material and by changing the structure of viral DNA. Together, these actions help suppress HIV from multiplying and keep the virus under control.
This approval matters because it broadens choices for oral medicines for people who are stable on treatment and may require a change in their therapy plan. Studies have shown that Idvynso is the first two-drug combination without an integrase inhibitor (also called an integrase strand transfer inhibitor, or INSTI) and without tenofovir to be as effective as standard oral regimens, including Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide [BIC/FTC/TAF]).
Why Was It Approved?
The FDA’s approval was based on data from two clinical trials involving adults with HIV-1 infection in whom the viral load was already well controlled and who had no history of treatment failure. In these studies, switching to once-daily Idvynso was found to be safe and just as effective in keeping the virus suppressed as staying on the standard three-drug combo of BIC/FTC/TAF. Both treatments resulted in maintaining very low viral levels and similar safety profiles.
In one clinical study involving 513 participants, 342 patients switched from the existing single-tablet regimen of BIC/FTC/TAF to once-daily Idvynso, and the remaining 171 patients stayed on their original BIC/FTC/TAF treatment. After 48 weeks, 1% of patients in both groups showed viral levels of 50 or more copies per milliliter. Also, viral levels remained fully suppressed in 92% of those who switched to Idvynso vs 94% who stayed on their original BIC/FTC/TAF treatment.
In the second clinical study involving 551 participants, 366 patients switched from various standard baseline antiretroviral therapy (bART) to once-daily Idvynso, and 185 patients continued with their original bART regimen. After 48 weeks, viral levels of 50 or more copies per milliliter were observed in 1% of those on Idvynso versus 5% of those on bART. Also, 96% of patients on Idvynso versus 92% on bART maintained viral suppression.
Overall, the results showed that the new pill worked as effectively as the existing therapies in keeping HIV load under control, with similar outcomes across age, sex, and racial groups, including adults 65 or older.
The common side effects seen included diarrhea, dizziness, fatigue, bloating, headache, and weight gain. The less common side effects included abdominal pain, rash, itching, and difficulty falling asleep.
A serious side effect involving a severe drop in platelet counts with sudden bruising (immune thrombocytopenia) after taking Idvynso for a month was seen in one patient. The patient recovered after stopping the medicine and receiving appropriate treatment.
What Do I Need to Know?
Take one Idvynso tablet every day, with or without food. If you miss a dose, take it right away unless it is almost time for the next dose. If you also take rifabutin, your health care provider may prescribe one doravirine tablet about 12 hours after your Idvynso dose.
Some medicines can reduce the amount of Idvynso in the body and make it less effective. Because of this, Idvynso should not be taken together with certain drugs that speed up the process by which the body breaks down medicines (e.g., cytochrome P450 3A inducers) or with the HIV medicines emtricitabine or lamivudine. Do not use Idvynso with other HIV-1 medicines because it is already a complete regimen.
Idvynso does not treat hepatitis B virus (HBV) infection. If you have HBV infection and switch from a plan that treats it, you should be monitored closely, and a specific HBV treatment should be considered as needed.
Share your full list of prescription, over-the-counter, and herbal medicines including St. John’s wort with your health care provider. Inform your health care provider about your medical history and whether you have taken rifabutin either recently or are planning to take it. They can check whether it is safe to use it with Idvynso or whether it may interfere with the treatment.
It is not known whether Idvynso affects a fetus or passes into breast milk. Talk to your health care provider if you are pregnant, planning to become pregnant, or breastfeeding.
Severe skin and hypersensitivity reactions have been reported in patients receiving doravirine‑containing regimens, including Stevens-Johnson syndrome/toxic epidermal necrolysis and DRESS (drug rash with eosinophilia and systemic symptoms). Call your health care provider right away if you develop a painful rash with fever, mouth sores, skin blisters or peeling, a swollen face or glands, red eyes, or if you feel very unwell.
Discuss your goals with your health care provider so that together you can decide if and when a switch to Idvynso fits your plan. Idvynso is expected to be available in pharmacies after May 11. Merck offers support to help you understand insurance coverage and possible copay assistance if you qualify.