Salix and Progenics received a Complete Response Letter (CRL) from the FDA following its review of a Supplemental New Drug Application (sNDA) for Relistor (methylnaltrexone bromide) injection for subcutaneous use for the treatment of opioid-induced constipation (OIC) in adult patients with chronic, non-cancer pain.

The CRL requests additional clinical data. Salix and Progenics intend to request an End-of-Review meeting with the Division of Gastroenterology and Inborn Errors Products to better understand the contents of the CRL.

Methylnaltrexone bromide is a peripherally acting mu–opioid receptor antagonist specifically designed to block the constipating effects of opioid pain medications in the gastrointestinal tract. Methylnaltrexone bromide does not cross the blood-brain barrier, therefore relieving the distressing effects of the constipation while retaining the analgesic effect of the opioid. Relistor Subcutaneous Injection has been FDA approved to treat constipation in patients with advanced illness and receiving palliative care, when response to laxative therapy has not been sufficient.

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