Acamprosate (calcium acetylhomotaurinate) has a chemical structure similar to that of amino acid neuromediators, such as taurine or gamma-amino-butyric acid (GABA), including an acetylation to permit passage across the blood brain barrier. Acamprosate may act by stimulating GABAergic inhibitory neurotransmission and antagonising excitatory aminoacids, particularly glutamate. Animal experimental studies have demonstrated that acamprosate affects alcohol dependence in rats, decreasing the voluntary intake of alcohol without affecting food and total fluid intake.
Acamprosate absorption across the gastrointestinal tract is moderate, slow and sustained and varies substantially from person to person. Food reduces the oral absorption of acamprosate. Steady state levels of acamprosate are achieved by the seventh day of dosing. Acamprosate is not protein bound.
Oral absorption shows considerable variability and is usually less than 10% of the ingested drug in the first 24 hours. The drug is excreted in the urine and is not metabolised significantly. There is a linear relationship between creatinine clearance values and total apparent plasma clearance, renal clearance and plasma half-life of acamprosate.
The kinetics of acamprosate are not modified in group A or B of the Child-Pugh classification of impaired liver function, a population which is likely to be part of the target population for acamprosate. This is in accordance with the absence of hepatic metabolism of the drug.
Preclinical Safety Data
In the preclinical studies, signs of toxicity are related to the excessive intake of calcium and not to acetylhomotaurine. Disorders of phosphorus/calcium metabolism have been observed including diarrhoea, soft tissue calcification, renal and cardiac lesions.
Acamprosate had no mutagenic or carcinogenic effect, nor any teratogenic or adverse effects on the male or female reproductive systems of animals. Detailed in vitro and in vivo research on acamprosate to detect genetic and chromosomal mutations has not produced any evidence of potential genetic toxicity.