LOS ANGELES—In a pivotal phase III trial, more than 70% of seriously ill patients with opioid-induced constipation responded to the investigational agent methylnaltrexone (MNTX) by the end of the first week of treatment. Neil Slatkin, MD, DABPN, reported the results at Digestive Disease Week (DDW) 2006 (abstract 686e).
Nearly half of the study patients experienced laxation within 4 hours of receiving their first dose of the drug, said Dr. Slatkin, director, Department of Supportive Care, Pain and Palliative Medicine, City of Hope, Duarte, California. He presented the research at a late-breaking abstract session.
"In order to provide the most compassionate care possible, health care professionals want to focus on aggressive pain management without the worry of opioid-induced bowel dysfunction," he said. "These data are encouraging for patients living with advanced illnesses who must take opioids to control their pain."
More than 50% of cancer patients admitted to palliative care units experience opioid-induced bowel dysfunction, which includes constipation that is not adequately addressed by current therapies such as laxatives or stool softeners, Dr. Slatkin commented.
Methylnaltrexone is a peripheral opioid-receptor antagonist designed to rapidly block the effect of opioid painkillers on opioid receptors outside the central nervous system. Since methylnaltrexone does not cross the blood-brain barrier, it does not interfere with brain-centered pain relief, according to the developers of the agent Wyeth Pharmaceuticals and Progenics Pharmaceuticals, Inc.
In the double-blind, placebo-controlled trial, 133 patients with advanced illness residing in nursing homes, hospice, and palliative care centers across the United States, were randomized to receive either methylnaltrexone (0.15 mg/kg subcutaneously) or placebo every other day for 2 weeks.
All of the patients experienced opioid-induced constipation, despite the use of laxatives and stool softeners, Dr. Slatkin said. No rescue laxatives were allowed within 4 hours of dosing.