>>/93609/
https://en.wikipedia.org/wiki/Memantine#Serotonin
> Memantine acts as a non-competitive antagonist at the 5-HT3 receptor, with a potency similar to that for the NMDA receptor.
А декс та же педивикия относит к агонистам мю-опиоидных рецепторов.
https://en.wikipedia.org/wiki/Dextromethorphan