Non-opioid antitussives inhibit endogenous glutamate release from rabbit hippocampal slices.

The non-opioid antitussive drugs, dextromethorphan, caramiphen and carbetapentane, are also anticonvulsant. The effects of these antitussives on potassium-stimulated release of endogenous amino acids from rabbit hippocampal slices was tested. All 3 drugs significantly reduced the release of glutamate, with carbetapentane being the most potent (IC50 approximately 40 microM). We suggest that the anticonvulsant action may be due to their ability to decrease glutamate release.