Severe myopathy commonly is a side effect of
Severe myopathy as a side effect is a classic adverse effect of statins. Statins are HMG-CoA reductase inhibitors used for hyperlipidemia. They inhibit cholesterol synthesis, but they also affect other isoprenoids like ubiquinone and geranylgerani, which are important for mitochondrial function and muscle integrity. This can lead to myopathy, including rhabdomyolysis, especially with certain statins like simvastatin or when combined with other drugs that inhibit CYP3A4, like cyclosporine or fibrates.
Wait, maybe the question is asking which drug causes this, and the options include statins. Let me check the structure. The user wants the explanation to follow the format they specified. The core concept is about statin-induced myopathy. The correct answer would be the statin class or a specific statin. The incorrect options might be other drugs like beta-blockers, ACE inhibitors, or calcium channel blockers, which don't typically cause myopathy.
For example, if the options were A. Beta-blockers, B. ACE inhibitors, C. Statins, D. Calcium channel blockers, then the correct answer is C. So the explanation would need to detail why statins cause myopathy through HMG-CoA reductase inhibition affecting ubiquinone and muscle cell function. The other options don't have this mechanism. Clinical pearl is to remember statins as a common cause and to check for drug interactions that increase risk.
**Core Concept**
Severe myopathy is a well-documented adverse effect of statins, particularly due to their mechanism of action involving HMG-CoA reductase inhibition. This enzyme is critical for cholesterol synthesis, but its inhibition also reduces ubiquinone production, impairing mitochondrial function in muscle cells.
**Why the Correct Answer is Right**
Statins inhibit HMG-CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis. This leads to reduced hepatic cholesterol stores, upregulation of LDL receptors, and decreased circulating LDL. However, the same pathway produces ubiquinone (coenzyme Q10), essential for mitochondrial electron transport. Depletion of ubiquinone impairs ATP synthesis in skeletal muscles, causing myopathy. Risk is heightened with high-dose statins (e.g., simvastatin) or concurrent use of CYP3A4 inhibitors (e.g., cyclosporine).
**Why Each Wrong Option is Incorrect**
**Option A:** Beta-blockers may cause fatigue but are not associated with myopathy.
**Option B:** ACE inhibitors can cause cough or angioedema, but not muscle toxicity.
**Option D:** Calcium channel blockers typically cause peripheral edema or constipation, not myopathy.
**Clinical Pearl / High-Yield Fact**
Remember the "statin-myopathy" link: myopathy is dose-dependent and synergistic with CYP3A4 inhibitors. Always check drug interactions when prescribing statins. A classic exam trap is confusing statins with other lipid-l