Акампросат, механизм действия

Throughout the years, however, the molecular target of acamprosate has remained elusive. Because of structural similarities, initial hypotheses centered on the possibility that acamprosate may act as a GABA-mimic or otherwise modulate GABA-ergic transmission. There is, however, little in the in vivo profile of acamprosate to suggest similarities with drugs known to enhance GABA-ergic transmission. In fact, a lack of sedative–ataxic or addictive properties is among the clinical advantages of acamprosate. Once it became clear that acamprosate’s mechanism of action is likely to involve modulation of glutamatergic function, several potential mechanisms were explored. For instance, acamprosate was shown to possess some partial agonist activity on the NMDA receptor complex via actions at its polyamine site. This would potentially allow it to act as a functional antagonist during hyperglutamatergic states. However, experiments failed to demonstrate this kind of functional activity. More recently, focus shifted to potential activity of acamprosate at metabotropic glutamate receptors (mGluRs). This was prompted, for example, by observations that acamprosate blocked neurotoxicity induced by trans-ACPD, an mGluR agonist with affinity for mGluR1 and mGluR5 receptors (Kiefer and Mann, 2010).

Over the years, the notion has become widely accepted that, although we may not know its exact mechanism of action, acamprosate is ‘a functional glutamate antagonist’. The paper by Spanagel et al (2005) in this issue fundamentally challenges this notion. The paper presents multiple lines of evidence that the reason it has been difficult to pin down the molecular site of acamprosate action may simply be because it does not exist. Instead, the authors propose that the activity attributed to acamprosate has all along reflected actions of the Ca++ it carries. The authors first thoroughly excluded agonist as well as antagonist activity of acamprosate at the glycine or glutamate sites of the NMDA receptor, respectively, as well as at the mGluR5 receptor. They then went on to demonstrate in vivo that, in contrast to the Ca++ salt, the sodium salt of acamprosate did not suppress relapse-like drinking. Conversely, the delivery of comparable amounts of Ca++ using a different carrier, gluconate, replicated suppression of relapse-like drinking. These animal findings are supported by secondary analyses of clinical trial data, which indicate that in acamprosate-treated patients positive outcomes are strongly correlated with plasma Ca++ levels. No such correlation exists in placebo-treated patients.

Acamprosate: An Alcoholism Treatment That May Not Be What We Thought

Современные лекарственные стратегии лечения алкоголизма

γ-Hydroxybutyrate (GHB), anticonvulsants, and α2-agonists have been studied as stand-alone or adjunctive agents in the treatment of alcohol withdrawal syndrome. Although these medications are promising for mild to moderate alcohol withdrawal syndrome, there is a dearth of information about their ability to prevent or treat complicated alcohol withdrawal.

Alcohol Disorders: Practical Tips From New Research

Combined Pharmacotherapies and Behavioral Interventions for Alcohol Dependence

Акампросат в лечении тревожных расстройств

BACKGROUND: Glutamate is a major excitatory neurotransmitter, while {gamma}-aminobutyric acid (GABA) is a predominant inhibitory neurotransmitter in the central nervous system. This GABA-glutamate imbalance is thought to play a role in the development of anxiety. Acamprosate calcium is thought to restore this chemical imbalance in alcohol withdrawal.

OBJECTIVE: To examine acamprosate calcium as augmentation therapy for treatment of anxiety.

METHODS: This 8-week, open-label study was designed to evaluate patients with anxiety who were stable on current medications (selective serotonin-reuptake inhibitors and serotonin-norepinephrine-reuptake inhibitors) but still symptomatic. Acamprosate was dosed at 1998 mg/day. Assessments included the Hamilton Rating Scale for Anxiety (HAM-A) and the Hospital Anxiety and Depression Scale.

RESULTS: Thirteen patients enrolled in the study and received study medication. Acamprosate reduced anxiety symptoms (mean HAM-A score reduction to 8.87 from a baseline of 20). Sixty-two percent of patients receiving acamprosate achieved remission (HAM-A score ≤7). Modal dose was 1998 mg/day (range 999-1998). The most commonly reported adverse events were nausea (n = 1), gastrointestinal upset (n = 1), and increased dream activity (n = 1).

CONCLUSIONS: Acamprosate calcium may be effective augmentation therapy in patients with treatment-resistant anxiety.

Acamprosate Calcium as Augmentation Therapy for Anxiety Disorders

налтрексон

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.

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.

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.

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Акампросат

Acamprosate May Be Helpful to Treat Alcohol Dependence