NEW YORK (Reuters Health) - Treatment with the drug ondansetron may lessen the symptoms of withdrawal in people addicted to morphine, oxycodone, and other opiate drugs, according to new research.

Dr. J. David Clark at Stanford University in Palo Alto, California, and colleagues studied whether ondansetron -- a drug usually used to treat nausea and vomiting caused by chemotherapy -- would ease opiate withdrawal in mice and humans. Their findings are published in the journal Pharmacogenetics and Genomics.

"One dimension of addiction is physical dependence, which can be modeled in rodents," the researchers explain. "The jumping behavior displayed by morphine-dependent mice after administration of (the anti-opiate drug naloxone) is a commonly used measure of physical dependence."

Clark's group treated mice for 4 days with increasing doses of morphine. Then the mice were given naloxone, and the researchers counted how many times the animals jumped in 15 minutes as a measure of physical dependence.

Treatment of the mice with ondansetron significantly reduced the jumping that was associated with morphine withdrawal, the report indicates.

The researchers next conducted a study in humans. Eight healthy male volunteers were pretreated with inactive "placebo" or ondansetron before receiving morphine followed by naloxone. Symptoms of withdrawal were significantly reduced in subjects given ondansetron.

"Although a patient receiving chronic opioid medications may not develop addiction, the physical dependence, tolerance and (increased pain sensitivity) that can develop may ... complicate ongoing patient management," Clark's group writes.

They conclude that treatment with drugs like ondansetron "may provide part of the solution to significant public health problems associated with opioid use."

SOURCE: Pharmacogenetics and Genomics, February 17th online, 2009.

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