FDA Delays Decision on Treatment for Opioid-Induced Constipation

Oral methylnaltrexone (Relistor) gets July target date

The FDA has extended the action date for its review of the new drug application for an oral formulation of methylnaltrexone bromide (Relistor, Valeant Pharmaceuticals International) by three months to July 19, 2016. The FDA extended the date to allow a full review of new information submitted by Valeant at the agency’s request.

Methylnaltrexone bromide administered as a subcutaneous (SC) injection was approved in the U.S. in 2008 for the treatment of opioid-induced constipation in adults with chronic noncancer pain and in adults with advanced illness who are receiving palliative care.

Methylnaltrexone is a mu-opioid receptor antagonist. As a quaternary amine, the ability of methylnaltrexone to cross the blood–brain barrier is restricted. This allows methylnaltrexone to function as a peripherally acting mu-opioid receptor antagonist in the gastrointestinal tract, thereby decreasing the constipating effects of opioids without affecting opioid-mediated analgesic effects on the central nervous system.

In clinical trials, the most common adverse events associated with SC methylnaltrexone in adult patients with opioid-induced constipation and chronic noncancer pain included abdominal pain, nausea, diarrhea, hyperhidrosis, hot flush, tremor, and chills. The most common adverse events in adult patients with opioid-induced constipation and advanced illness included abdominal pain, flatulence, nausea, dizziness, and diarrhea.

Source: Valeant Pharmaceuticals; March 4, 2016; and Relistor Prescribing Information; September 2014.