Sunday, October 24, 2010
A New/Old Treatment for Opiate Addiction
Gov makes naltrexone legit for heroin.
Last week, the government officially sanctioned the use of naltrexone, trade name Vivitrol, for use in the treatment of heroin addiction. Approved years ago by the FDA for use in the treatment of alcoholism, naltrexone is a long-acting opiate receptor antagonist that has been widely used for heroin detoxification, withdrawal, and maintenance for some time. In that light, the official approval was a bit of an anticlimax, and of less scientific interest than naltrexone’s earlier approval for alcohol dependence.
While naltrexone has yet to become the huge treatment breakthrough for alcoholism that addiction researchers hoped for it, naltrexone did, in the end, prove to be the first anti-craving medication widely available for alcoholics. Using an opiate antagonist as an aid to the prevention of alcoholic relapse would have been unthinkable without the underpinnings of a neurophysiological model of addiction. Various investigators have also speculated that naltrexone, the drug used as an adjunct of heroin withdrawal therapy, may find use against symptoms of marijuana withdrawal in people prone to marijuana dependence
Naltrexone has something of a mixed reputation, however, in part due to its use in the highly controversial practice of “rapid detox.” Naltrexone, like methadone and buprenorphine, blocks the heroin high in a relatively neutral manner. It does so by knocking the opiate molecule off its receptors and replacing it with “dead weight,” so to speak. Naltrexone would seem to be the perfect drug for heroin addicts—but it is not. It does little to reduce cravings. Like acamprosate for alcohol, another blocking approach, its record of accomplishment is mixed, and the dropout rate is high. There is not even a mild drug-like effect to provide cross-tolerance and dampen the effects of withdrawal, as with methadone. Recently, naltrexone for heroin addiction has been offered as a form of rapid detoxification. The addict is anesthetized and placed on a respirator, then injected with naltrexone. The result: complete detoxification in a matter of hours, as the naltrexone molecules knock the opium molecules off their receptors. It can be lethal if not carefully controlled and supervised. The problem, as always, is that the detoxified addict is just as vulnerable to heroin addiction as before. Rapid detox does nothing to combat subsequent cravings, and relapse is frequent.
Naltrexone combined with buprenorphine is marketed as Subutex, and represents another treatment modality for opiate addiction. In addition, a University of Minnesota study of kleptomania—the compulsion to steal—showed that naltrexone drastically reduced stealing among a group of 25 shoplifters.
Naltrexone will be offered as a monthly injection, an approach that has not been widely tested on opiate addicts, but is potentially an advantage over frequent visits to methadone clinics or daily ingestion of other treatment drugs. Unfortunately, naltrexone is a potential problem for people with liver disease or hepatitis. At high doses, naltrexone has been implicated in liver damage. More common adverse effects include dizziness, lethargy, and headache.
Graphics Credit: http://www.cancercenter.ph/