Homotaurine (also known as tramiprosate (INN), 3-amino-1-propanesulfonic acid, or 3-APS) is a natural amino acid found in seaweed. It is analogous to taurine, but with an extra carbon in its chain. It has GABAergic activity, apparently by mimicking GABA, which it resembles.
Homotaurine was investigated in a Phase III clinical trial as a potential treatment for Alzheimer's disease that did not show efficacy. A study in cognitive impairment done in 2018 did show positive benefits.
Homotaurine has been reported as a GABA antagonist, as well as a GABA agonist.In vitro studies have found that homotaurine is a GABAA partial agonist as well as a GABAB receptor partial agonist with low efficacy, becoming an antagonist and displacing the full agonists GABA and baclofen at this receptor. In a study in rats, homotaurine reversed the catatonia induced by baclofen (the prototypical GABAB agonist), and was able to produce analgesia via the GABAB receptor, an effect that was abolished when CGP-35348, a GABAB receptor antagonist was applied.
One study in rats showed that homotaurine suppressed ethanol-stimulated dopamine release, as well as ethanol intake and preference in rats in a way similar to the N-acetyl derivative of homotaurine, acamprosate. Acamprosate was approved by the FDA in 2004 to treat alcohol dependence.
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