Opioid antagonists for alcohol dependence

BACKGROUND

Alcohol dependence belongs to the globally leading health risk factors. Therapeutic success of psychosocial programs for relapse prevention is moderate and could be increased by an adjuvant treatment with the opioid antagonists naltrexone and nalmefene.

OBJECTIVES

To determine the effectiveness and tolerability of opioid antagonists in the treatment of alcohol dependence.

SEARCH STRATEGY

We searched the Cochrane Drugs and Alcohol Group (CDAG) Specialized Register, PubMed, EMBASE and CINAHL in January 2010 and inquired manufacturers and researchers for unpublished trials.

SELECTION CRITERIA

All double-blind randomised controlled trials (RCTs) which compare the effects of naltrexone or nalmefene with placebo or active control on drinking-related outcomes.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted outcome data. Trial quality was assessed by one author and cross-checked by a second author.

MAIN RESULTS

Based on a total of 50 RCTs with 7793 patients, naltrexone reduced the risk of heavy drinking to 83% of the risk in the placebo group RR 0.83 (95% CI 0.76 to 0.90) and decreased drinking days by about 4%, MD -3.89 (95% CI -5.75 to -2.04). Significant effects were also demonstrated for the secondary outcomes of the review including heavy drinking days, MD - 3.25 (95% CI -5.51 to -0.99), consumed amount of alcohol, MD - 10.83 (95% CI -19.69 to -1.97) and gamma-glutamyltransferase, MD - 10.37 (95% CI -18.99 to -1.75), while effects on return to any drinking, RR 0.96 (95 CI 0.92 to 1.00) missed statistical significance. Side effects of naltrexone were mainly gastrointestinal problems (e.g. nausea: RD 0.10; 95% CI 0.07 to 0.13) and sedative effects (e.g. daytime sleepiness: RD 0.09; 95% CI 0.05 to 0.14). Based on a limited study sample, effects of injectable naltrexone and nalmefene missed statistical significance. Effects of industry-sponsored studies, RR 0.90 (95% CI 0.78 to 1.05) did not significantly differ from those of non-profit funded trials, RR 0.84 (95% CI 0.77 to 0.91) and the linear regression test did not indicate publication bias (P = 0.765).

AUTHORS' CONCLUSIONS

Naltrexone appears to be an effective and safe strategy in alcoholism treatment. Even though the sizes of treatment effects might appear moderate in their magnitudes, these should be valued against the background of the relapsing nature of alcoholism and the limited therapeutic options currently available for its treatment.

Acamprosate for alcohol dependence

BACKGROUND

Alcohol dependence is among the main leading health risk factors in most developed and developing countries. Therapeutic success of psychosocial programs for relapse prevention is moderate, but could potentially be increased by an adjuvant treatment with the glutamate antagonist acamprosate.

OBJECTIVES

To determine the effectiveness and tolerability of acamprosate in comparison to placebo and other pharmacological agents.

SEARCH STRATEGY

We searched the Cochrane Drugs and Alcohol Group (CDAG) Specialized Register, PubMed, EMBASE and CINAHL in January 2009 and inquired manufacturers and researchers for unpublished trials.

SELECTION CRITERIA

All double-blind randomised controlled trials (RCTs) which compare the effects of acamprosate with placebo or active control on drinking-related outcomes.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data. Trial quality was assessed by one author and cross-checked by a second author. Individual patient data (IPD) meta-analyses were used to verify the primary effectiveness outcomes.

MAIN RESULTS

24 RCTs with 6915 participants fulfilled the criteria of inclusion and were included in the review. Compared to placebo, acamprosate was shown to significantly reduce the risk of any drinking RR 0.86 (95% CI 0.81 to 0.91); NNT 9.09 (95% CI 6.66 to 14.28) and to significantly increase the cumulative abstinence duration MD 10.94 (95% CI 5.08 to 16.81), while secondary outcomes (gamma-glutamyltransferase, heavy drinking) did not reach statistical significance. Diarrhea was the only side effect that was more frequently reported under acamprosate than placebo RD 0.11 (95% 0.09 to 0.13); NNTB 9.09 (95% CI 7.69 to 11.11). Effects of industry-sponsored trials RR 0.88 (95% 0.80 to 0.97) did not significantly differ from those of non-profit funded trials RR 0.88 (95% CI 0.81 to 0.96). In addition, the linear regression test did not indicate a significant risk of publication bias (p = 0.861).

AUTHORS' CONCLUSIONS

Acamprosate appears to be an effective and safe treatment strategy for supporting continuous abstinence after detoxification in alcohol dependent patients. Even though the sizes of treatment effects appear to be rather moderate in their magnitude, they should be valued against the background of the relapsing nature of alcoholism and the limited therapeutic options currently available for its treatment.

Acamprosate supports abstinence, naltrexone prevents excessive drinking: evidence from a meta-analysis with unreported outcomes

Two pharmacological agents have repeatedly been shown to be efficacious for relapse prevention in alcohol dependence: The putative glutamate-antagonist acamprosate and the opioid-antagonist naltrexone. Clinical evidence for both drugs is based on various outcome criteria. Whereas for acamprosate primarily abstinence maintenance has been demonstrated, studies with naltrexone have mostly emphasised the prevention of heavy drinking. The remaining effects of both drugs are not always reported; accordingly the corresponding database is fragmentary. Thus, the primary objective of the present meta-analysis was to complete the efficacy profiles for acamprosate and naltrexone and to compare them with each other. Unreported results, requested from the study investigators and the drug manufacturers, were integrated in the computation of effect sizes. For the meta-analysis, emphasis was placed on the conceptual distinction between having a first drink and returning to heavy drinking. Naltrexone was found to have a significant effect on the maintenance of abstinence as well as the prevention of heavy drinking. Acamprosate was shown only to support abstinence; it did not influence alcohol consumption after the first drink. When the efficacy profiles of the two drugs were compared, acamprosate was found to be more effective in preventing a lapse, whereas naltrexone was better in preventing a lapse from becoming a relapse. The superiority of either one drug or over the other one cannot be determined as a general rule, it rather depends on the therapeutic target. Benefits in the treatment of alcohol dependence might be optimized by matching the efficacy profiles of specific antidipsotropics with the motivational status of alcohol-dependent patients.

Pharmacoprophylaxis of alcohol dependence: Review and update Part II: Efficacy

Alcohol dependence is a major problem in India. The pharmacological armamentarium for relapse prevention of alcohol has widened with the addition of new drugs. In this article, we review the pharmacology and efficacy of the four most important such drugs: disulfiram, naltrexone, acamprosate and topiramate. The first part of this two-part review series concerns the comparative pharmacology and the second part concerns the efficacy studies. Overall, all four of these drugs have modest but clinically significant usefulness as pharmacoprophylactic agents for relapse prevention or minimization of alcohol dependence. Combinations might be helpful, especially for naltrexone and acamprosate. The issue of supervision and compliance remains important, especially for such drugs as disulfiram and naltrexone. Topiramate is a promising new agent and requires further study. Disulfiram, while very effective in compliant patients, presents challenges in terms of patient selection and side effects. For patients with hepatic impairment, acamprosate is a good choice.

Acamprosate in the treatment of alcoholism: mechanisms and perspectives

Acamprosate, calcium acetyl homotaurinate, was first developed and tested in the early 1980s in France and has been available in the USA since 2004. Its major mechanism of action is the reduction of cerebral hyperexcitability by interacting with glutamate receptors. More than 20 randomized, placebo-controlled trials have been conducted. With very few exceptions, these studies have demonstrated a significant benefit of acamprosate over placebo. Side effects of acamprosate, such as diarrhoea, are benign and transient. Studies in which acamprosate was given in combination with disulfiram or naltrexone also showed promising results. Further studies are underway to identify potential acamprosate responders on a neurobiological basis. If successful, this would allow an individually targeted prescription of acamprosate that would then further improve its efficacy and cost–effectiveness.

Long-term effects of pharmacotherapy on relapse prevention in alcohol dependence

BACKGROUND

There is growing evidence that pharmacological treatment with two of the best validated anticraving drugs, acamprosate and naltrexone, is efficacious in promoting abstinence in recently detoxified alcohol-dependent subjects.

OBJECTIVE

The stability of effects after termination of treatment remains to be answered, especially when combining both the drugs.

METHOD

After detoxification, 160 alcohol-dependent subjects participated in a randomized, double-blind, placebo-controlled trial. Patients received naltrexone or acamprosate or a combination of naltrexone and acamprosate or placebo for 12 weeks. Patients were assessed weekly by interview, self-report, questionnaires and laboratory screening. Additionally, follow-up evaluation based on telephone interview of participants, general practitioners and relatives was conducted 12 weeks after terminating the medication.

RESULTS

At week 12, the proportion of subjects relapsing to heavy drinking was significantly lower in the group with combined medication compared with both placebo and acamprosate (P < 0.05). No difference was detectable between acamprosate and naltrexone, both of which were superior to placebo (P < 0.05). Relapse rates were 28% (combined medication), 35% (naltrexone), 50% (acamprosate) and 75% (placebo). After follow-up (week 24), combined medication led to relapse rates significantly lower than placebo, but not lower than acamprosate. Again, both naltrexone and acamprosate were superior to placebo. Relapse rates were 80% (placebo), 54% (acamprosate), 53% (naltrexone) and 34% (combined medication).

CONCLUSIONS

The results of this study highlight the stability of effects of pharmacotherapy on relapse prevention in alcohol dependence.

The efficacy of acamprosate in the maintenance of abstinence in alcohol-dependent individuals: results of a meta-analysis

BACKGROUND

A number of clinical trials have been undertaken to determine the efficacy of acamprosate in the maintenance of abstinence in alcohol-dependent individuals. However, the reported differences in patient populations, treatment duration, and study endpoints make comparisons difficult. An assessment of the efficacy of treatment with acamprosate was, therefore, undertaken using meta-analytical techniques.

METHODS

All randomized, placebo-controlled trials (RCTs) that fulfilled predetermined criteria were identified using (1) a language unrestricted search of 10 electronic databases; (2) a manual search of relevant journals, symposia, and conference proceedings; (3) cross-referencing of all identified publications; (4) personal communications with investigators; and (5) scrutiny of Merck-Santé's internal reports of all European trials. Study quality was assessed, independently, by three blinded workers. Key outcome data were identified; some outcome variables were recalculated to ensure consistency across trials. The primary outcome measure was continuous abstinence at 6 months; abstinence rates were determined by estimating Relative Benefit (RB).

RESULTS

A total of 19 published 1 unpublished RCTs were identified that fulfilled the selection criteria; 3 were excluded because the documentation available was insufficient to allow adequate assessment. The remaining 17 studies, which included 4087 individuals, 53% of whom received active drug, were of good quality and were otherwise reasonably comparable. There was no evidence of publication bias. Continuous abstinence rates at 6 months were significantly higher in the acamprosate-treated patients (acamprosate, 36.1%; placebo, 23.4%; RB, 1.47; [95% confidence intervals (CI): 1.29-1.69]; p < 0.001). This effect was observed independently of the method used for assigning missing data. The effect sizes in abstinent rates at 3, 6, and 12 months were 1.33, 1.50, and 1.95, respectively. At 12 months, the overall pooled difference in success rates between acamprosate and placebo was 13.3% (95% CI, 7.8-18.7%; number needed to treat, 7.5). Acamprosate also had a modest but significant beneficial effect on retention (6.01%; [95% CI, 2.90-8.82]; p = 0.0106).

CONCLUSION

Acamprosate has a significant beneficial effect in enhancing abstinence in recently detoxified, alcohol-dependent individuals.