Gabapentin May Help Alcoholics Recover From Dependence

Allison Gandey

August 15, 2008

August 15, 2008 — A pilot study suggests that small doses of gabapentin (Neurontin, Pfizer) may deter heavy drinking and help alcoholic-dependent patients recover. The drug, often used to treat epilepsy and chronic pain, appeared to delay the onset of relapse among alcoholics as well as the risk for relapse during this 6-week study and for another 6 weeks after treatment ended.

But researchers are quick to point out the preliminary nature of their work and the small sample size of the study, which is published in the August issue of the journal Alcoholism: Clinical and Experimental Research.

In addition to exploring the effect of gabapentin on alcohol dependence, investigators also studied its usefulness in treating insomnia. They were surprised to learn that gabapentin performed no better than placebo on this end point.

"Contrary to expectation, gabapentin did not improve Sleep Problems Questionnaire [SPQ] scores any more than placebo did during the 6 weeks of its administration," reports the research team, led by Kirk Brower, MD, from the University of Michigan, in Ann Arbor.

As part of the SPQ assessment, patients were asked how often in the last month they:

  • Had trouble falling asleep.

  • Woke up several times per night.

  • Had trouble staying asleep (including waking far too early).

  • Woke up after an usual amount of sleep feeling tired and worn out.

Nearly 14 million Americans meet the diagnostic criteria for alcohol abuse or alcoholism. According to the US Substance Abuse and Mental Health Services Administration, alcohol problems, alone or in combination with illegal drug use, account for 40% of admissions to addiction treatment programs each year.

An estimated 70% of people with alcohol problems have comorbid insomnia. "There may be some underlying chemical changes in the brain that prompt alcoholics to report more insomnia as a coexisting condition than nonalcoholics," coauthor Flavia Consens, MD, also at the University of Michigan, said in a news release.

Gabapentin Did Not Aid Insomnia

In this randomized, double-blind study of gabapentin vs placebo, investigators looked at 21 patients. Participants met study criteria for alcohol dependence and insomnia and expressed a desire to abstain from alcohol.

During a 1- to 2-week placebo lead-in and screening phase, investigators took a complete medical history, conducted a physical exam, and performed a variety of blood tests to rule out other medical problems as well as a urine drug test. Researchers conducted structured interviews to determine eligibility and patterns of alcohol use and sleep.

Subjects were then randomized to either placebo or gabapentin for 6 weeks and titrated over a 10-day period to 1500 mg or 5 pills at bedtime. After a 4-day taper, subjects were reassessed 6 weeks after ending treatment.

At the end of the study, drinking outcomes could not be assessed for 6 of 7 subjects who did not complete the study, and these were conservatively considered heavy drinkers, the authors note. One other noncompleter was confirmed as a heavy drinker.

At 6 weeks, 3 of 10 (30%) subjects in the gabapentin group were categorized as having relapsed to heavy drinking, vs 9 of 11 (81.8%) on placebo (P = .03). After adjustment for education, the relative risk of relapse to heavy drinking in the gabapentin group was significantly lower (relative risk, 0.25; P = .047).

Of the 14 who completed week 6, 12 were followed to week 12, again with the 2 subjects lost to follow-up considered relapsed to heavy drinking. Using intention-to-treat analysis, they found that 6 of 10 (60%) subjects in the gabapentin group relapsed to heavy drinking vs 11 of 11 in the placebo group (P = .04).

Although continuous abstinence was more common in the gabapentin group, the difference was not statistically significant in intention-to-treat analysis.

A total of 38 adverse events among 20 subjects were reported as either possibly or probably related to study medication (20 events in gabapentin subjects and 18 events for placebo).

The most common adverse effects attributed to gabapentin vs placebo were somnolence (3 vs 1), headache (3 subjects in each group), dizziness (2 vs 1), indigestion (2 vs 4), nerve or muscle pain (2 vs none), and altered mental state such as feeling spacey or fuzzy (0 vs 2).

In total, 6 events, including 4 in the gabapentin group, were rated as moderate or severe, and all others were rated as mild.

Dr. Brower and his team conclude that bedtime administration of gabapentin appeared to delay the onset to heavy drinking in alcoholics but did not help insomnia as measured by either subjective report or polysomnography.

"Future studies should employ larger sample sizes and examine the efficacy of gabapentin for relapse prevention in the absence of insomnia, determine optimal dosing, monitor subjects for longer periods of time, and assess for discontinuation syndromes," they write.

The researchers also emphasize that testing gabapentin alone and in combination with cognitive-behavioral therapy for insomnia will also be important, given the early successes of therapy in treating alcohol-dependent subjects.

This study was funded by a grant from the National Center for Research Resources, a component of the National Institutes of Health. The study drug was provided by Parke-Davis, a subsidiary of Pfizer.

Alcohol Clin Exp Res. 2008;32:1429-1438. Abstract

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