Cardiac glycosides

Cardiac glycoside general structure

Digitalis and its derivatives such as digoxin and digitoxin are cardiac glycosides used typically in the therapy of congestive heart failure and atrial fibrillation.

Liver toxicity of Cardiac glycosides

The cardiac glycosides have not been linked to serum enzyme elevations during therapy or with instances of clinically apparent liver injury.

Mechanism of action of Cardiac glycosides

Digitalis (dij" i tal' is), digoxin (di jox' in) and digitoxin (dij" i tox' in) are cardiac glycosides that enhance myocardial contractility, probably by increasing levels of myocardial cytosolic calcium because of inhibition of sodium-potassium ATPase. Originally derived from the purple foxglove flower (Digitalis purpurea), the cardiac glycosides have been used in clinical medicine for more than two centuries. Once used as first-line agents for congestive heart failure and atrial fibrillation, the cardiac glycosides have been replaced by agents that are better tolerated and have been shown to improve long term survival such as the ACE inhibitors and beta-blockers.

The cardiac glycosides are now reserved largely for patients with left ventricular systolic dysfunction and atrial fibrillation or for patients with congestive heart failure in sinus rhythm and residual symptoms despite maximal alternative therapy. Digitalis has been available for over a century. Digoxin, derived from Digitalis lanatus, was introduced as having more reliable pharmacokinetics and remains the major form of cardiac glycosides used today.

FDA approval information for Cardiac glycosides

The cardiac glycosides are approved treatment of mild-to-moderate congestive heart failure and for control of the ventricular response rate in patients with atrial fibrillation.

FDA approval information for Cardiac glycosides

Digoxin is available in tablets of ranging from 0.0625 to 0.5 mg generically and under the brand name Lanoxin. The typical dose is 0.125 to 0.25 mg daily, but dosing is often individualized because of tolerance and effect. Digoxin is also available in solution for intravenous administration as well as an oral solution. The cardiac glycosides have many side effects that are largely dose related and require careful monitoring of drug levels.

Side effects of Cardiac glycosides

The most common side effects include dizziness, fatigue, headache, anxiety, gastrointestinal upset, change in taste and blurred vision. Severe side effects include seizures and coma, heart block, atrial and ventricular arrhythmias and sudden cardiac death.

• Dailymed label info on Cardiac glycosides
• FDA Cardiac glycosides

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