Abstract: A process is disclosed for the interconversion of alkaloids of the heteroyohimbane group, more particularly of tetrahydroalstonine into raubasine, having the formulae ##STR1## according to which the asymmetry center at C-20 is inverted by several steps involving changes of the ring E structure.

Abstract: The invention relates to novel steroid compounds having the formula ##STR1## and their glycoside derivatives containing a pyridazine ring, in which particularly the substituent R.sub.4 is a hydroxy group or a hexopyranoside unit or a chain of two or three hexopyranoside units, as it is normally found in the molecule of the natural glycosides; one or even all the hydroxy groups contained in the R.sub.4 can be either free or etherified or esterified with either a simple carboxylic acid or a carboxylic acid bearing basic groups, or even acetalized with an aldehyde or a ketone, depending on the position and the orientation of a pair of hydroxy groups. The subject compounds are endowed with cardiotonic activity. The invention moreover relates to the process for the preparation of the above compounds and to their therapeutic use.