**Question:** Drug induced myopathy can be caused by all of the following except -

A. High dose steroids
B. Anti-epileptic drugs
C. Calcium channel blockers
D. Amiodarone

**Correct Answer:** .

**Core Concept:** Drug-induced myopathy is a condition characterized by muscle weakness and damage caused by medications. It can occur due to various factors, including pharmacological properties of the drug, dosage, and patient-specific factors. Understanding the drugs that are less likely to cause myopathy is essential for safe prescribing and patient care.

**Why the Correct Answer is Right:** Option A, high dose steroids, is indeed a common cause of myopathy due to their immunosuppressive and anti-inflammatory properties. Steroids can lead to muscle weakness, pain, and elevated creatine kinase (CK) levels in some patients.

Option B, anti-epileptic drugs, such as carbamazepine, phenytoin, and phenobarbital, can cause myopathy due to their impact on muscle membrane stability and calcium homeostasis.

Option C, calcium channel blockers, primarily affect blood vessels and heart, not muscle directly. However, long-term use of these drugs can lead to myopathy due to secondary effects like hypokalemia, hypocalcemia, and hypomagnesemia, which can cause muscle weakness and CK elevation.

Option D, amiodarone, is a complex drug with multiple pharmacological effects, including antiarrhythmic, anti-inflammatory, and immunomodulatory properties. Amiodarone-induced myopathy is characterized by elevated CK levels, muscle pain, and weakness.

**Why Each Wrong Option is Incorrect:**

Option A (high dose steroids) and D (amiodarone) cause myopathy directly due to their pharmacological properties, making them incorrect in this context.

Option B (anti-epileptic drugs) and C (calcium channel blockers) cause myopathy indirectly by affecting electrolyte levels, making them incorrect as well.

**Why the Correct Answer is Right:** Calcium channel blockers (C) are less likely to cause myopathy directly due to their specific target organ involvement (blood vessels and heart) rather than muscle. While they can indirectly affect muscle through electrolyte imbalances, this is less specific than the direct myotoxicity of steroids, amiodarone, and anti-epileptic drugs.

**Clinical Pearls:**

1. **Potassium-sparing diuretics** like spironolactone and amiloride can also cause myopathy indirectly by impairing electrolyte balance. However, the focus here is on drugs that directly affect muscle cells or cause electrolyte imbalances, making calcium channel blockers less likely.
2. **Avoiding the use of these drugs in patients with risk factors for myopathy, such as kidney dysfunction, hypokalemia, or hypomagnesemia, is crucial to minimize the risk of drug-induced myopathy.** Promptly recognizing and managing these side effects can prevent myopathy progression and severe complications.
3. **Electrolyte