The structure of the ring-opened N-beta-propyl-ajmaline (Neo-Gilurytmal (R)) at physiological pH is obviously responsible for its better absorption and bioavailability when compared with ajmaline (Gilurytmal (R))

Prajmaline, the semisynthetic propyl derivative of ajmaline, shows a much b etter bioavailability when compared with the Rauvolfia alkaloid ajmaline. E arly NMR and IR-studies, fluorescence spectroscopic investigations and extr action experiments combined with ion-pair chromatography proved the thesis of a tautomeric equilibrium between an aldehyde-amine and a quaternary carb inol-ammonium component. The aim of this study was to confirm this thesis b y HPLC-separation and by structure-determination of both tautomeric compoun ds.