Today we are still insufficiently informed, experimentally as well as clinically, about the action of digitalis. This is by no means due to any scarcity of research in this field. On the contrary, there is hardly a drug that has been so fully investigated. That we know so little about digitalis, in spite of all this research, is due partly to the fact that we often use, in these experiments, the ordinary tinctures, extracts and infusions. Such preparations contain a multiplicity of substances, both active and inactive, which influence each other's solubility and pharmacologic action, giving an equation with many unknown factors. The large number of these unknown items no doubt accounts for the great discrepancies which one finds continually in the literature about the action of digitalis.
The following is a schematic analysis of folia digitalis:
Similarly to digitoxin, the other two glucosides also can be split up into