Cardiac glycosides are a class of organic compounds that increase the output force of the heart and increase its rate of contractions by acting on the cellular sodium-potassium ATPase pump. They are selective steroidal glycosides and are important drugs for the treatment of heart failure and cardiac rhythm disorders.
What is the mechanism of action of cardiac glycosides?
Mechanism of action and toxicity
Cardiac glycosides inhibit the Na+‐K+‐ATPase on cardiac and other tissues, causing intracellular retention of Na+, followed by increased intracellular Ca2+ concentrations through the effect of the Na+‐Ca2+ exchanger.
What are the indication of cardiac glycosides?
Today glycosides have 3 indications: manifest and chronic cardiac insufficiency, arrhythmia absoluta and paroxysmal supraventricular tachycardia. Glycosides are no longer important in the therapy of acute cardiac insufficiency.
Why are cardiac glycosides useful for treating heart patients?
Cardiac glycosides have long served as the main medical treatment to congestive heart failure and cardiac arrhythmia, due to their effects of increasing the force of muscle contraction while reducing heart rate.
What are the different types of cardiac glycosides?
types of cardiac glycosides
What are the 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.
What is the antidote for cardiac glycoside?
Digoxin immune FAB is a specific antidote that may be effective in some forms of cardiac glycoside plant poisoning. This agent has been used successfully in patients with oleander toxicity and may cross-react with other cardiac glycosides.
What is the effect of inotropic agents to the heart?
Inotropic agents, or inotropes, are medicines that change the force of your heart’s contractions. There are 2 kinds of inotropes: positive inotropes and negative inotropes. Positive inotropes strengthen the force of the heartbeat. Negative inotropes weaken the force of the heartbeat.
Which family is rich in cardiac glycosides?
Cardiac glycosides are found in some plant families, such as Apocynaceae (Asclepias sp. L. and Nerium oleander L.) and Plantaginaceae (Digitalis lanata Ehrh.
How do you test for cardiac glycosides?
A solution of glycosides is treated with a small amount of Kedde reagent (Mix equal volumes of a 2% solution of 3, 5 dinitrobenzoic acid in menthol and a 7.5% aqueous solution of KOH). Development of a blue or violet colour that faded out in1 to 2 hrs shows it presence of cardinoloids.
How do cardiac glycosides reduce heart rate?
Cardiac glycosides are a class of medications that inhibit the Na+ K+ ATPase enzyme, increasing the force of heart contractions. The most commonly prescribed cardiac glycoside is digoxin, which can be used to treat atrial fibrillation, atrial flutter, and congestive heart failure.
How do cardiac glycosides cause a positive inotropic effect?
Digoxin, a cardiac glycoside, exerts its positive inotropic effects by inhibiting the plasma membrane Na+,K+-ATPase of cardiac myocytes. This leads to an increase in available Ca2+ as described earlier.
What does digoxin do to the heart?
Digoxin is a type of drug called a cardiac glycoside. Their function is to slow your heart rate down and improve the filling of your ventricles (two of the chambers of the heart) with blood. For people with atrial fibrillation, where the heart beats irregularly, a different volume of blood is pumped out each time.
What are the 2 types of cardiac glycosides based on their steroidal skeleton?
There are two main types, which either have a steroidal aglycone with 23 carbons (the cardenolide glycosides) or 24 carbons (the bufadienolide glycosides).
Which are the direct and indirect actions of cardiac glycosides?
Their direct effect is in inhibiting the membrane sodium-potassium (Na+-K+) pump, raising intracellular levels of sodium and leading to an accumulation of intracellular calcium. This in turn increases cardiac contractility. Their indirect effect is in enhancing vagal tone.
Do cardiac glycosides increase blood pressure?
Blood pressure effects of cardiac glycosides in humans have been infrequently reported. Although direct infusion of ouabain or digoxin causes vasoconstriction, indirect effects of cardiac glycosides may have the opposite effect, owing to changes in sympatho-vagal balance.