Prader-Willi syndrome groups raise safety concerns over first approved hyperphagia drug Vykat XR

Advocacy groups for Prader-Willi syndrome have issued a warning about potential safety risks associated with Vykat XR, the first medication approved for managing extreme hunger in affected individuals, amid reports of serious adverse events and fatalities.

Prader-Willi syndrome advocacy groups have warned doctors and families about possible safety concerns linked to Vykat XR, the first approved medicine for treating hyperphagia, the extreme hunger that affects people with the genetic disorder. In a joint statement, the Prader-Willi Syndrome Association USA, the Foundation for Prader-Willi Research and the International Prader-Willi Syndrome Organisation said reports submitted to the US Food and Drug Administration included seven deaths and more than 100 serious adverse events among people taking diazoxide choline extended-release, the drug sold as Vykat XR.

The groups said the reports do not prove the medicine caused the deaths or complications, noting that people with Prader-Willi syndrome often have complex medical needs and a higher mortality rate than the general population. They also pointed out that published data suggest annual mortality in the condition ranges from 1% to 3% across age groups. Even so, the statement urged clinicians to treat the reports seriously, particularly because fluid overload may heighten the risk of severe reactions.

According to Healio’s earlier reporting, the FDA approved diazoxide choline extended-release in March 2025 for adults and children aged 4 years and older with Prader-Willi syndrome. The approval was based on phase 3 data showing that patients who stopped the drug and switched to placebo had worsening hyperphagia-related behaviour compared with those who stayed on treatment. Common adverse events in the trial included hypertrichosis, oedema, hyperglycaemia and rash.

The organisations and the clinicians who signed the statement said future research should look more closely at possible risks in patients with obesity, heart disease, pre-existing swelling, severe breathing problems, untreated or poorly treated obstructive sleep apnoea and a history of serious respiratory infections or pneumonia. They advised individual assessment, close monitoring and extra testing before and during treatment, especially when doses are being increased, and said doctors may need to consider echocardiography and other checks for fluid retention. Healio said it had contacted Neurocrine Biosciences for comment.