The Hospice Clinician Blog

Pruritis is a common—and troublesome—side effect of opioids, often experienced by hospice patients. At Washington University’s Center for the Study of Itch, researchers have been studying mice models to better understand opioid-induced pruritis.

Investigators have discovered that a particular variant of the mu-opioid receptor (MOR) in the spinal cord called MOR1D specifically controls pruritis. When they blocked MOR1D in the spinal cord of mice, they were able to block morphine-induced pruritis without affecting morphine’s analgesic effect. In fact, analgesia appears to be mediated through a completely different spinal cord receptor, MOR1. In mice, blocking MOR1 eliminated analgesia, but not pruritis.

Dr. Zhou-Feng Chen, PhD, the principal investigator and director of Washington University’s Center for the Study of Itch, proposed that additional variants of the mu-opioid receptor may mediate other common side opioid side effects, such as nausea, respiratory depression and constipation. Dr. Chen hopes that the center’s research will help generate novel therapies aimed at opioid-induced pruritis, and perhaps other side effects as well. This research may one day benefit our hospice patients.

Reference: Cell 2011;147:447-458.

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