Neurocrine Biosciences Inc. (NASDAQ:NBIX) stock fell almost 5% on Wednesday before recovering after physicians and experts in Prader-Willi syndrome notified clinicians of some cases of deaths and severe complications potentially associated with Vykat XR (diazoxide choline).
The San Diego-based company added Vykat after acquiring Soleno Therapeutics Inc. for $53 per share in cash, totaling approximately $2.9 billion.
The acquisition aimed to expand Neurocrine’s portfolio with Vykat XR, the first FDA-approved treatment for hyperphagia in Prader-Willi syndrome, which could significantly enhance its revenue potential as the company strengthens its position in the endocrinology and rare disease markets.
The FDA approved the drug in 2025 to manage hyperphagia in PWS patients four years and older; the medication carries warnings regarding edema and fluid overload.
Seven Deaths Reported In FDA Adverse Event Data
According to data from the FDA Adverse Event Monitoring System as of July 31, 2026, there have been seven reported deaths and more than 100 serious adverse events, primarily involving edema, respiratory, and cardiac issues.
Individuals facing these adverse outcomes frequently had complex medical histories, pre-existing obesity, and multiple concurrent medications.
While the reports cannot definitively prove whether Vykat XR directly caused these incidents, doctors note that baseline PWS mortality ranges between 1% and 3% annually.
Certain underlying conditions appear to elevate safety risks during treatment initiation or dose adjustment. These key factors include severe obesity, heart problems, pre-existing fluid retention, severe breathing difficulties, untreated sleep apnea, and a history of severe respiratory infections.
Q2 Sales of $54 Million
Vykat XR second-quarter 2026 net product sales were $54 million from May 18, 2026, the closing date of the Soleno acquisition. Unaudited pro forma full-quarter net product sales were $94 million.
Healthcare providers considering this therapy should conduct comprehensive individual assessments before initiating treatment. Recommended measures include conducting baseline testing, such as echocardiograms, and monitoring for fluid retention.
Physicians are urged to consider slowing the drug’s titration process and carefully watching for warning symptoms like rapid weight gain, dyspnea, orthopnea, or worsening edema.
NBIX Stock Price Activity: Neurocrine Biosciences shares were down 2.07% at $159.63 at the time of publication on Wednesday, according to Benzinga Pro data.
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