New drug formulation may help drug addicts quit

An injectable, sustained-release formulation of naltrexone is a safe and effective treatment for patients who are addicted to opioid drugs, such as heroin, new research suggests.

Naltrexone in oral form is very effective in preventing and reversing the effects of opioid drugs. However, it has not been particularly useful because patients often stop taking it, according to the report in the Archives of General Psychiatry. The development of a longer lasting naltrexone formulation has renewed interest in this drug.

Dr. Sandra D. Comer, from the College of Physicians and Surgeons of Columbia University in New York, and colleagues assessed the outcome of 60 heroin-dependent adults who were randomly assigned to receive injections of sustained-release naltrexone, at a 192-mg or 384-mg dose, or placebo. This formulation can block the effects of injected drugs for three to five weeks, depending on the dose.

At the end of the eight-week trial, 60 percent and 68 percent of patients in the low- and high-dose naltrexone groups, respectively, remained in treatment, whereas the majority of patients in the placebo group dropped out. The average time to dropout ranged from 27 days for the placebo group to 48 days for the high-dose naltrexone group.

The percentage of urine samples that were negative for opioid drugs was highest for high-dose naltrexone and lowest for placebo, the authors point out.

Side effects with naltrexone, at either dose, were uncommon and generally mild, the report indicates. Moreover, the injectable formulation of the drug was well tolerated.

“The availability of sustained-release formulations of naltrexone holds the promise of allowing patients to circumvent their ambivalence to taking the medication and to focus instead on other issues relevant to sustaining abstinence,” the authors conclude.

SOURCE: Archives of General Psychiatry, February 2006.

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