Digitalis glycosides congestive heart failure

The outcome of this is to couple ATP hydrolysis with the vectorial transport of Na+ and K+ across the plasma membrane. The inhibition of the (Na+-K+)-ATPase by cardiac glycosides such as digitalis (an extract of foxglove leaves), which blocks the dephosphorylation of the E2-P form of the enzyme, is the basis for a number of steroid drags which are commonly prescribed for the treatment of congestive heart failure. 

Crude leaf preparations of Digitalis have been in medical use since 1785. Pure cardiac glycosides are now available. These preparations in injectable tinctures or powdered leaf tablets are used extensively for the treatment of congestive heart failure. They increase the force of the heart muscle and the power of systolic contraction, apparently by inhibiting the active transport of K and Na ions through cell membranes. 

Adverse effects Thiazide diuretics induce hypokalemia and hyperuricemia in 70% of patients, and hyperglycemia in 10% of patients. Serum potassium levels should be monitored closely in patients who are predisposed to cardiac arrhythmias (particularly individuals with left ventricular hypertrophy, ischemic heart disease, or chronic congestive heart failure) and who are concurrently being treated with both thiazide diuretics and digitalis glycosides (see p. 160). Diuretics should be avoided in the treatment of hypertensive diabetics or patients with hyperlipidemia. 

Digitalis glycosides are positive inotropic agents used in the management of patients with congestive heart failure. They control ventricular rate in supraventricular arrhythmias including atrial fibrillation and atrial flutter. 

Edema and specific drugs for its treatment have long been problems of the physician and of the chemist interested in medicinal products. Digitalis and the many related cardiac glycosides were the first effective agents for the treatment of dropsy associated with congestive heart failure. However, it was soon recognized that the mobilization of the excess tissue fluid associated with this condition was due to a primary action on the heart with improved cardiovascular hemodynamics and only secondarily to an action upon the kidney. 

The adverse effects of carbenoxolone include an increase in blood pressure (both systolic and diastolic), fluid retention and reduced serum potassium levels. The incidence of these adverse effects is said in some reports to be as high as 50% others quote lower figures. Hypertension and fluid retention occur early in carbenoxolone treatment, whereas the hypokalae-mia develops later and may occur in the absence of the other two adverse effects. " Carbenoxolone is therefore unsuitable for patients with congestive heart failure, or those taking digitalis glycosides, unless measures to avoid hypokalaemia are taken. 

The digitalis-like glycosides are the basic therapy for congestive failure. The toad poisons (bufagins, bufotalins, or bufotoxins) and the Eryth-rophleum alkaloids show promise as potentially useful drugs for this form of heart disease. 

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