Magazine article Clinical Psychiatry News

Methylnaltrexone Relieves Opioid-Induced Constipation

Magazine article Clinical Psychiatry News

Methylnaltrexone Relieves Opioid-Induced Constipation

Article excerpt

ORLANDO -- Single injections of methylnaltrexone relieved opioid-induced constipation in 4 hours for 60% of hospice and palliative care patients in a randomized, placebo-controlled phase III trial.

The earliest responses occurred within 5 minutes, and most patients responded within 2 hours, investigator Jay Thomas, M.D., reported at the annual meeting of the American Society of Clinical Oncology. The patients in the trial had not had a bowel movement for at least 48 hours prior to treatment, despite being on a stable laxative regimen for at least 3 days.

Dr. Thomas, clinical medical director of the San Diego Hospice and Palliative Care Center, reported that the single-dose trial enrolled 154 patients with advanced medical disease from 16 hospices. Of the 154 patients, 123 (80%) had cancer. The population also included patients with pulmonary disorders (12) AIDS (8), amyotrophic lateral sclerosis (3), cardiovascular conditions (2), and other disorders (6).

"These patients were very sick and near the end of life," Dr. Thomas said. Since most patients lived at home, visiting nurses trained family members to give the injections in place of an enema or other rescue regimen. If the study drug did not provide relief within 4 hours, rescue was permitted.

The trial randomized patients into three groups: 52 patients were given a placebo, 57 received 0.15 mg/kg of methylnaltrexone, and 55 received 0.30 mg of methylnaltrexone/kg. Median time to laxation was 70 minutes for the 0.15-mg dose, 45 minutes at 0.30 mg, and more than 1,440 minutes (24 hours) with placebo.

Dr. Thomas, an internist, said the difference in efficacy between the two methylnaltrexone doses was negligible. "With the higher dose, you didn't get more bang for your buck," he said. "If anything, you got more side effects."

Side effects were minimal, however. The two most common adverse events, abdominal cramping and flatulence, were associated with successful laxation. The next most common side effects were nausea and dizziness.

The trial's sponsor, Progenies Pharmaceuticals Inc. of Tarrytown, N.Y., has already started a second phase III study at 30 centers to assess repetitive doses in patients with chronic constipation due to opioid painkillers. …

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