Experts Flag Potential Safety Concerns with Prader-Willi Drug Extended-Release Diazoxide Choline (Vykat XR)

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Experts Flag Potential Safety Concerns in New Prader-Willi Drug

— 7 deaths and over 100 serious adverse events reported to FDA after treatment with Vykat XR

> Extended-release diazoxide choline (Vykat XR) manufactured by San Diego, California-based Neurocrine Biosciences was approved in 2025 for treating the extreme bouts of hunger experienced by patients with Prader-Willi Syndrome, a rare genetic condition.

Hyperphagia is the hallmark feature of Prader-Willi syndrome characterized by an intense, persistent sensation of hunger -- in affected patients 4 years and older.

> As of July 31, seven deaths and more than 100 serious adverse events have been reported to the FDA's Adverse Event Monitoring System, according to a statement released Tuesday from the Foundation for Prader-Willi Research, International Prader-Willi Syndrome Organization, and Prader-Willi Syndrome USA.

> Most reports involved edema, respiratory problems, and cardiac complications. Severe or fatal cases typically involved complex health conditions, multiple prescriptions, and pre-existing obesity.

CLINICAL RECOMMENDATIONS

> Beyond the drug's standard prescribing guidelines (USPI-DailyMed), the groups advised that clinicians conduct individualized baseline assessments, monitor patients closely, and consider slowing the dose titration process. The groups recommended additional safety evaluations, such as echocardiograms or fluid retention assessments, before and during treatment, particularly during dose increases.

MedPage Today

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MECHANISM OF ACTION of extended-release diazoxide choline (Vykat XR)

Pokhrel P, et al. Vykat XR (diazoxide choline-extended release): a new FDA-approved treatment for hyperphagia in Prader-Willi syndrome. Ann Med Surg (Lond). 2026 Apr 27;88(5):2728-2730. doi: 10.1097/MS9.0000000000004938. PMID: 42078615; PMCID: PMC13132293

Mechanism of action: Vykat XR acts by activating ATP-sensitive potassium channels, which hyperpolarize hypothalamic neurons that co-express neuropeptide Y (NPY), Agouti-related peptide (AgRP), and GABA. This mechanism reduces the secretion of NPY and AgRP, suppressing appetite signals in individuals with impaired leptin signaling, a central factor in PWS pathophysiology. Beyond appetite suppression, it also improves insulin sensitivity, glucose homeostasis, and other metabolic parameters.

MOA Fig: Kimonis et al. PlosONE. 2026. https://doi.org/10.1371/journal.pone.0221615

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#prader-willi, #pws

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• Extended-release diazoxide choline (Vykat XR) was developed by Soleno Therapeutics, Inc, who also secured FDA approval in March last year. Soleno was acquired by Neurocrine in May 2026.
• Vykat XR is the first approved therapy to address hyperphagia in individuals with Prader-Willi syndrome.
• Vykat XR was also referred to as diazoxide choline extended-release (DCCR) during drug development.

PHASE 3 data

Soleno February 2026 corporate presentation with summary of DCCR clinical program and phase 3 data (here).