Nausea Drug Shows Promise as a Treatment for Opioid Withdrawal
Stanford University Scientists have discovered that the drug ondansetron (Zofran), which is commonly used to combat nausea, can prevent withdrawal symptoms associated with opioid compounds such as heroin, morphine, oxycodone, and hydrocodone.
Lead investigator Dr. Larry Chu and his team published the results of their study in the Feb. 17 online issue of the Journal of Pharmacogenetics and Genomics.
The abuse of opioid compounds has escalated in recent years, with drugs such as Oxycontin becoming increasingly popular among young adults. According to the 2007 survey by National Survey on Drug Use and Health, approximately 12.5 million Americans aged 12 or older are using prescription paid medications for non-medical purposes. Although opioid compounds are highly effective for reducing pain, patients can quickly develop a tolerance to this class of drugs and problems with dependency, abuse and addiction can easily occur.
Addiction to heroin or other short-acting opioids produces behavioral disruptions that are usually incompatible with a productive life. Because abruptly stopping the use of opiates can cause a constellation of withdrawal symptoms, many people addicted to opiates continue to use them rather than seek treatment. Withdrawal symptoms include nausea, vomiting, diarrhea, fever, chills, agitation, and insomnia.
To compound the problem, treatment for opiate withdrawal has been historically inadequate. Treatment options have traditionally included cross-tolerance, in which patients are prescribed a non-opiate pain medication for which the dose is gradually lowered; oral clonidine, which decreases adrenergic neurotransmission in the locus ceruleus in the brain, the site where withdrawal symptoms originate; activation of the endogenous opioid system without medication, for instance by using acupuncture; and rapid detoxification with opiate antagonists such as naltrexone.
The most successful treatment to date for heroin addiction has been stabilization on methadone, which can result in an addiction to methadone.
According to researchers from Stanford's Department of Anesthesia, the drug ondansetron blocks certain 5-HT3 receptors that are involved in withdrawal symptoms. Initial tests were conducted in mice and followed by tests in eight healthy, non-opioid dependent volunteer subjects. The volunteers were given two doses of morphine, one of which was accompanied by ondansetron. The researchers found that ondansetron reduced withdrawal symptoms in the volunteers.
Ondansetron is regarded as the prototypical 5-HT3 antagonist. This class of drugs was first introduced in the early 1990s. Since, the 5-HT3 antagonists have become the most widely used drugs for chemotherapy-induced emesis. The antiemetic effects of this class of drugs persist long after they disappear from the blood circulation, suggesting their continued interaction at the receptor level. This allows ondansetron to be effectively administered once daily. Unlike other drugs used for opioid withdrawal, ondansetron doesn't lead to addiction and it can be taken in an outpatient setting. Stanford researchers plan to conduct further studies to determine the role ondansetron might play in reducing opioid addiction. Previous studies have shown than ondansetron reduces alcohol consumption in laboratory animals, and currently it is being tested in humans as a treatment for alcoholism.