Acamprosate, sold under the brand name Campral, is a medication used along with counselling to treat alcohol dependence.
|Trade names||Campral EC|
|Other names||N-Acetyl homotaurine, Acamprosate calcium (JAN JP), Acamprosate calcium (USAN US)|
|Elimination half-life||20 h to 33 h|
|CompTox Dashboard (EPA)|
|ECHA InfoCard||100.071.495 |
|Chemical and physical data|
|Molar mass||181.211 g/mol g·mol−1|
|3D model (JSmol)|
Acamprosate is thought to stabilize chemical signaling in the brain that would otherwise be disrupted by alcohol withdrawal. When used alone, acamprosate is not an effective therapy for alcoholism in most individuals; studies have found that acamprosate works best when used in combination with psychosocial support since it facilitates a reduction in alcohol consumption as well as full abstinence.
Serious side effects include allergic reactions, abnormal heart rhythms, and low or high blood pressure, while less serious side effects include headaches, insomnia, and impotence. Diarrhea is the most common side-effect. Acamprosate should not be taken by people with kidney problems or allergies to the drug.
Acamprosate is useful when used along with counseling in the treatment of alcohol dependence. Over three to twelve months it increases the number of people who do not drink at all and the number of days without alcohol. It appears to work as well as naltrexone.
Acamprosate is primarily removed by the kidneys and should not be given to people with severely impaired kidneys (creatinine clearance less than 30 mL/min). A dose reduction is suggested in those with moderately impaired kidneys (creatinine clearance between 30 mL/min and 50 mL/min). It is also contraindicated in those who have a strong allergic reaction to acamprosate calcium or any of its components.
The US label carries warnings about increases of suicidal behavior, major depressive disorder, and kidney failure.
Other frequent adverse effects include headache, stomach pain, back pain, muscle pain, joint pain, chest pain, infections, flu-like symptoms, chills, heart palpitations, high blood pressure, fainting, vomiting, upset stomach, constipation, increased appetite, weight gain, edema, sleepiness, decreased sex drive, impotence, forgetfulness, abnormal thinking, abnormal vision, distorted sense of taste, tremors, runny nose, coughing, difficulty breathing, sore throat, bronchitis, and rashes.
Ethanol and benzodiazepines act on the central nervous system by binding to the GABAA receptor, increasing the effects of the inhibitory neurotransmitter GABA (i.e., they act as positive allosteric modulators at these receptors). In chronic alcohol abuse, one of the main mechanisms of tolerance is attributed to GABAA receptors becoming downregulated (i.e. these receptors become less sensitive to GABA). When alcohol is no longer consumed, these down-regulated GABAA receptor complexes are so insensitive to GABA that the typical amount of GABA produced has little effect, leading to physical withdrawal symptoms; since GABA normally inhibits neural firing, GABAA receptor desensitization results in unopposed excitatory neurotransmission (i.e., fewer inhibitory postsynaptic potentials occur through GABAA receptors), leading to neuronal over-excitation (i.e., more action potentials in the postsynaptic neuron). One of acamprosate's mechanisms of action is the enhancement of GABA signaling at GABAA receptors via positive allosteric receptor modulation. It has been purported to open the chloride ion channel in a novel way as it does not require GABA as a cofactor, making it less liable for dependence than benzodiazepines. Acamprosate has been successfully used to control tinnitus, hyperacusis, ear pain and inner ear pressure during alcohol use due to spasms of the tensor tympani muscle.
In addition, alcohol also inhibits the activity of N-methyl-D-aspartate receptors (NMDARs). Chronic alcohol consumption leads to the overproduction (upregulation) of these receptors. Thereafter, sudden alcohol abstinence causes the excessive numbers of NMDARs to be more active than normal and to contribute to the symptoms of delirium tremens and excitotoxic neuronal death. Withdrawal from alcohol induces a surge in release of excitatory neurotransmitters like glutamate, which activates NMDARs. Acamprosate reduces this glutamate surge. The drug also protects cultured cells from excitotoxicity induced by ethanol withdrawal and from glutamate exposure combined with ethanol withdrawal.
Acamprosate is not metabolized by the human body. Acamprosate's absolute bioavailability from oral administration is approximately 11%, and its bioavailability is decreased when taken with food. Following administration and absorption of acamprosate, it is excreted unchanged (i.e., as acamprosate) via the kidneys.
In October 2001 Forest Laboratories acquired the rights to market the drug in the US.
As of 2015 acamprosate was in development by Confluence Pharmaceuticals as a potential treatment for fragile X syndrome. The drug was granted orphan status for this use by the FDA in 2013 and by the EMA in 2014.
Society and culture
In addition to its apparent ability to help patients refrain from drinking, some evidence suggests that acamprosate is neuroprotective (that is, it protects neurons from damage and death caused by the effects of alcohol withdrawal, and possibly other causes of neurotoxicity).
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It has been hypothesized that long-term ethanol exposure alters the expression or activity of specific GABAA receptor subunits in discrete brain regions. Regardless of the underlying mechanism, ethanol-induced decreases in GABAA receptor sensitivity are believed to contribute to ethanol tolerance, and also may mediate some aspects of physical dependence on ethanol. ... Detoxification from ethanol typically involves the administration of benzodiazepines such as chlordiazepoxide, which exhibit cross-dependence with ethanol at GABAA receptors (Chapters 5 and 15). A dose that will prevent the physical symptoms associated with withdrawal from ethanol, including tachycardia, hypertension, tremor, agitation, and seizures, is given and is slowly tapered. Benzodiazepines are used because they are less reinforcing than ethanol among alcoholics. Moreover, the tapered use of a benzodiazepine with a long half-life makes the emergence of withdrawal symptoms less likely than direct withdrawal from ethanol. ... Unfortunately, acamprosate is not adequately effective for most alcoholics.
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Due to the complex nature of this drug's MMOA, and a paucity of well defined target affinity data, we do not map to a primary drug target in this instance.
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Acamprosate is a NMDA glutamate receptor antagonist and a positive allosteric modulator of GABAA receptors.
Marketed formulations contain acamprosate calcium
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Acamprosate is thought to stabilize the chemical balance in the brain that would otherwise be disrupted by alcoholism, possibly by blocking glutaminergic N-methyl-D-aspartate receptors, while gamma-aminobutyric acid type A receptors are activated. ... The mechanism of action of acamprosate in maintenance of alcohol abstinence is not completely understood. Chronic alcohol exposure is hypothesized to alter the normal balance between neuronal excitation and inhibition. in vitro and in vivo studies in animals have provided evidence to suggest acamprosate may interact with glutamate and GABA neurotransmitter systems centrally, and has led to the hypothesis that acamprosate restores this balance. It seems to inhibit NMDA receptors while activating GABA receptors.
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