Potassium may be intimately involved to the action of cardiac glycosides. Chlorine and potassium also act as diuretics. The
elements chlorine, manganese, potassium and sodium are determined by instrumental neutron activation analysis in all the cardiotonic
drugs which are currently used in Greece. All the available pharmaceutical forms of these drugs were analysed (pills, injections,
water solutions). It has been found that there is a wide variation among the different values for managanese, sodium and chlorine
while for potassium values are relatively constant. Results are discussed from the pharmacological point of view. It is proposed
to study the role of manganese in cardiotonic drugs as well as the effect of potassium addition in oral pharmaceutical form
of cardiotonic drugs in decreasing the toxicity of cardiac glycosides.