Acamprosate, sold under the brand name Campral, is a medication used along with counselling to treat alcohol dependence. 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. Until it became a generic in the United States, Campral was manufactured and marketed in the United States by Forest Laboratories, while Merck KGaA markets it outside the US.
Medical uses
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.
Contraindications
Acamprosate is primarily removed by the kidneys and should not be given to people with severely impaired kidneys. A dose reduction is suggested in those with moderately impaired kidneys. It is also contraindicated in those who have a strong allergic reaction to acamprosate calcium or any of its components.
Adverse effects
The US label carries warnings about increases of suicidal behavior, major depressive disorder, and kidney failure. Adverse effects that caused people to stop taking the drug in clinical trials included diarrhea, nausea, depression, and anxiety. Other frequent adverse effects include headache, stomach pain, back pain, muscle pain, joint pain, chest pain, infections, flu-like symptoms, chills, heart palpitations, highblood 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.
Pharmacology
Pharmacodynamics
The pharmacodynamics of acamprosate are complex and not fully understood; however, it is believed to act as an NMDA receptor antagonist and positive allosteric modulator of GABAA receptors. Ethanol and benzodiazepines act on the central nervous system by binding to the GABAA receptor, increasing the effects of the inhibitory neurotransmitter GABA. In chronic alcohol abuse, one of the main mechanisms of tolerance is attributed to GABAA receptors becoming downregulated. 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, leading to neuronal over-excitation. 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. Chronic alcohol consumption leads to the overproduction 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 was developed by Lipha, a subsidiary of Merck KGaA. and was approved for marketing in Europe in 1989. In October 2001 Forest Laboratories acquired the rights to market the drug in the US. It was approved by the FDA in July 2004. The first generic versions of acamprosate were launched in the US in 2013. 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
"Acamprosate" is the INN and BAN for this substance. "Acamprosate calcium" is the USAN and JAN. It is also technically known as N-acetylhomotaurine or as calcium acetylhomotaurinate. It is sold under the brand name Campral.
Research
In addition to its apparent ability to help patients refrain from drinking, some evidence suggests that acamprosate is neuroprotective.
