Possible Interaction: Digitalis and Calcium Supplement

“Experimental evidence suggests … concentrations of digitalis increase … Ca ²⁺-overloaded cardiac cells by decreasing the inhibition of the Na⁺-K⁺ pump by Ca<…+</sup>, thereby leading to a reduction in Ca²⁺ overload and to an increase in force of contraction.”

“More specifically, … speculated that digitalis has the ability to alter the configuration … cell membrane of cardiac muscle, thus increasing calcium and sodium influx during depolarization; these cations then are taken up by sarcoplasmic reticulum which … in the release of microsomal-bound calcium into the myoplasm surrounding the contractile machinery.”

“ Digitalis glycosides increase the intracellular calcium concentration by entering the cell interior and acting on the ryanodine receptors and by forming transmembrane calcium channels.”

“The conflation of … the case of digitalis … calcium may be the acceptance of Bower’s shaky case reports at the expense of Lieberman’s stronger—and arguably more useful—… most important determinant of calcium toxicity is the dose and rate of infusion,whether or not digitalis glycosides are present.”

“The … the digitalis … calcium ions availability for the electromechanical coupling and an increase of the intramyocardial pressure; the increase of the adrenergic activity determined contemporary an increase … of the myocardial cells, a rise of vascular tone and coronary artery tone and a reduction of the duration of the diastole.”

“Initial management was difficult because of the risks associated with concomitant administration of calcium and digitalis.”

“drip of Ca and repeated use of digitalis shows atoxic effect; and 4) respiratory failure improves without stopping i.v.”

“ Digitalis inhibits the Na+/K+ ATPase enzyme and indirectly increases intracellular calcium concentration.”

“Since the inotropic effect of digitalis appears to be related to cell membrane transport of calcium , we studied the effect of digoxin on diaphragmatic contractility in 20 anesthetized dogs.”

“The interaction observed between cardiac glycosides and the Ca++ channel blocker suggests that Ca++ movements across the sarcolemma may influence the inotropic effect of digitalis or its toxicity.”