All are cardiotoxic except –
**Core Concept**
The question requires knowledge of cardiotoxic substances and their effects on the heart. Cardiotoxicity can manifest as arrhythmias, myocardial depression, or cardiac arrest, among other symptoms.
**Why the Correct Answer is Right**
Digoxin (correct answer) is a cardiac glycoside used to treat heart failure and atrial fibrillation. However, it can cause cardiotoxicity, particularly at high doses or with pre-existing electrolyte imbalances. Digoxin inhibits the Na+/K+-ATPase pump, leading to increased intracellular sodium, which in turn increases intracellular calcium and enhances contractility. However, excessive calcium can lead to arrhythmias and cardiac arrest.
**Why Each Wrong Option is Incorrect**
**Option A:** Doxorubicin is an anthracycline antibiotic that is known to cause cardiotoxicity through the generation of reactive oxygen species, leading to mitochondrial damage and apoptosis.
**Option B:** Cisplatin is a platinum-based chemotherapeutic agent that can cause cardiotoxicity by inducing vascular endothelial damage and increasing oxidative stress.
**Option C:** Cyclophosphamide is an alkylating chemotherapeutic agent that can cause cardiotoxicity by inducing DNA damage and altering cardiac ion channels.
**Clinical Pearl / High-Yield Fact**
When prescribing cardiac glycosides like digoxin, it's essential to monitor electrolyte levels, particularly potassium and magnesium, to prevent cardiotoxicity.
**Correct Answer: D. Cisplatin**