A study in the July 2004 issue of Alcoholism: Clinical a Experimental Research examines the effects of acamprosate (calcium acetyl homotaurinate), a medication used in Europe and elsewhere to prevent relapse in alcoholics, and currently under review for use by the U.S. Food and Drug Administration. The study's findings, in conjunction with previous research, indicate that acamprosate should be safe to take when people are drinking, and should not make them want to drink more or behave differently over and above the effects of alcohol alone.
"To our knowledge, this is the first published report that examines potential interactions between acamprosate and alcohol in humans," said Elisabeth J. Houtsmuller, assistant professor of behavioral biology at Johns Hopkins University School of Medicine and corresponding author for the study. "Other studies have shown that acamprosate helps people abstain from drinking, and our study examined what may underlie this. Because acamprosate acts on a neurotransmitter system the glutamate system that alcohol also has many effects on, we thought it was possible that acamprosate might change some of alcohol's effects, and this might be part of why it helps people to abstain. We therefore examined whether acamprosate alters the way alcohol makes people feel."
The findings suggest that acamprosate does not alter the rate of absorption or elimination of alcohol by the body, the disrupting effects of alcohol on performance tasks, or most of alcohol's mood effects, she said.
Acamprosate 'Well Tolerated'"The glutamate system is one of the most strongly affected by chronic alcohol use," added Raymond Anton, Distinguished Professor and director of the Center for Drug and Alcohol Programs at the Medical University of South Carolina. "Following the initiation of abstinence, it takes considerable time for the brain chemistry of this system to become 'normal' again. It is thought that acamprosate helps speed this process so that the person has a greater chance of staying abstinent by not 'turning to the bottle' to feel normal. Acamprosate is well tolerated but needs to be taken a few times per day, unlike disulfiram and naltrexone, which can be taken once per day."
For this study, adult participants (7 males, 3 females) were recruited through local advertising. All of the participants were classified as heavy drinkers, having reported alcohol consumption a minimum of eight days per month; with five or more drinks per occasion at least three times a month for the men, and four or more drinks per occasion at least three times a month for the women. During the six-week study, subjects received three different doses of oral acamprosate (0, 2 and 4 g.) for 11 days on each dose. Physiological, subjective and psychomotor measures were collected daily during each dosing cycle. During each of the acamprosate dose conditions, subjects also received three different doses of alcohol (0, 0.5 and 1.0 g/kg) during three separate laboratory sessions. Researchers collected the subjective, physiological and psychomotor effects of the alcohol as well as breath-alcohol levels at baseline and at 30-minute intervals for three hours following administration.
Results indicate that acamprosate does not appear to alter alcohol's pharmacokinetics (the way it moves through the body), acute physiological or psychomotor alcohol effects, or most subjective alcohol effects.
Subjects Were Not Alcoholics"While the results of this study are rather clear and straightforward, namely, that acamprosate has minimal effects on the alcohol experience, the findings should be interpreted cautiously because only a few subjects were studied and those subjects were not alcoholics," said Anton. "Since people vary in medication response, generalizing from a study of only a few people is difficult. Also, we know that chronic alcohol use changes brain chemistry in ways that might make medications and alcohol-response interactions different. However, given these cautions, the study is consistent with a growing body of literature and clinical experience that acamprosate should be safe to take when people are drinking and it should not make them want to drink more, or behave differently over and above the effects of alcohol alone."
"In fact," he said, " not enough of this is done during drug development. This is especially true of medications that work on the brain and liver, where alcohol has its major effects. It is important to know whether a medication can alter the metabolism of alcohol, for example, increasing blood alcohol levels that would make the person more intoxicated per unit of drink consumed, or increase levels of intoxication by direct brain interaction with alcohol.