2-(2-(Methylamino)ethyl)pyridine dihydrochloride 2-Pyridineethanamine, N-methyl-, dihydrochloride 5579-84-0 5638-76-6 Antivom Betahistine dihydrochloride Betahistine hydrochloride Betahistine hydrochloride [USAN] Betaserc EINECS 226-966-5 Microser PT 9 Serc Vasomotal