Why cardiac glycosides are toxic?
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 toxic effects of digoxin?
The clinical features of toxicity are often non-specific. They commonly include lethargy, confusion and gastrointestinal symptoms (anorexia, nausea, vomiting, diarrhoea and abdominal pain). Visual effects (blurred vision, colour disturbances, haloes and scotomas) are rarer in contemporary practice.
What is the effect of cardiac glycosides?
Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump.
What toxicity is digitalis glycosides?
Digitalis glycosides have a narrow therapeutic index, and toxicity is mostly dose-related. Gastrointestinal disturbances: anorexia, nausea and vomiting (largely a central effect at the chemoreceptor trigger zone), and diarrhoea.
What is cardiac toxicity?
Cardiotoxicity is a condition when there is damage to the heart muscle. As a result of cardiotoxicity, your heart may not be able to pump blood throughout your body as well. This may be due to chemotherapy drugs, or other medications you may be taking to control your disease.
In which conditions the cardiac glycosides are contraindicated?
Cardiac disease Cardiac glycosides are contraindicated in conditions in which there is obstruction to ventricular outflow, for example hypertrophic obstructive cardiomyopathy, constrictive pericarditis, and cardiac tamponade. Acute myocarditis may also increase the risk of toxicity.
How does digoxin toxicity cause tachycardia?
Overall, digoxin slows the conduction and increases the refractory period in cardiac tissue by enhancing vagal tone. These actions of digoxin can result in almost every type of arrhythmia possible such as: Extrasystole. Nonparoxysmal junctional tachycardia.
How does digoxin toxicity affect potassium?
(1) Digoxin inhibits the cardiac Na/K antiporter (orange oval, above). This causes an increase in intracellular sodium and a decrease in intracellular potassium. The decrease in intracellular potassium is what causes hyperkalemia in patients with digoxin overdose.
What causes digitalis toxicity?
Digitalis toxicity can be caused by high levels of digitalis in the body. A lower tolerance to the drug can also cause digitalis toxicity. People with lower tolerance may have a normal level of digitalis in their blood. They may develop digitalis toxicity if they have other risk factors.
What do cardiac glycosides inhibit?
Cardiac glycosides are a family of steroids that bind and inhibit the Na+,K+-ATPase with high selectivity and affinity. Traditionally, these substances were extracted from plants such as Digitalis purpurea or foxglove (digitalis), Strophanthus gratus (ouabain) or amphibian skin (Bufo marinus-bufalin, marinobufagenin).
What are cardiac glycosides called?
Cardiac glycosides are a class of medications commonly derived from foxglove plants, such as Digitalis lanata and Digitalis purpurea. The most commonly prescribed cardiac glycoside is digoxin.
What drugs cause cardiotoxicity?
The most common chemotherapy drugs related to cardio-toxicity include:
- 5-fluorouracil (Adrucil)
- Paclitaxel (Taxol)
- Anthracyclines (a class of drugs)
- Targeted therapies: such as monoclonal antibodies and tyrosine kinase inhibitors.
- Some Leukemia drugs.