A once-a-month PrEP pill may be on its way. For a new drug to come to market, it must pass at least three different trials before being submitted to the FDA for approval for use in the U.S. Islatravir, formerly known as MK-8591, is being developed by the pharma company, Merck. It has already reached its second stage of trials. Following promising results, it looks likely to go to Phase 3 trials, bringing it one step closer to approval. In its phase 2 trial, 250 participants at low-risk of HIV were recruited to receive either six monthly doses of Islatravir or a placebo. Those taking Islatravir were monitored to see how quickly the medicine entered their bodies and how long it remained potent. The Islatravir participants were found to have levels of the drug, “well above the prespecified PK threshold for HIV-1”. Last November, the FDA called a long-acting PrEP injection a “breakthrough therapy”. Cabotegravir has been designed to be administered by a health professional once every eight weeks. Designating a treatment as a ‘breakthrough’ means the FDA has been impressed by trial results and will work with a pharmaceutical company to speed up a therapy going through the approval process.