Simvastatin
Brand names: Zocor
Class: 🧪 Statins
When a vignette puts you on a statin and a CYP3A4 inhibitor in the same regimen, simvastatin is usually the wrong answer. It is a moderate-intensity statin (high-intensity at 80 mg is no longer recommended due to rhabdomyolysis risk) used for primary and secondary ASCVD prevention. Simvastatin is heavily metabolized by CYP3A4, so dose ceilings exist with amlodipine (max 20 mg), diltiazem and verapamil (max 10 mg), and amiodarone (max 20 mg). Avoid grapefruit juice and strong CYP3A4 inhibitors entirely. For most patients needing high-intensity therapy or CYP3A4 freedom, atorvastatin or rosuvastatin is the better pick. Contraindicated in pregnancy and active liver disease.
✅ Indications
ASCVD prevention, dyslipidemia.
⚙️ Mechanism of Action
HMG-CoA reductase inhibitor.
📏 Dosing
10–40 mg PO at bedtime. 80 mg rarely used (↑ myopathy risk).
🚫 Contraindications
Active liver disease, pregnancy, concurrent potent CYP3A4 inhibitors.
⚠️ Adverse Effects
Myalgia, ↑ LFTs, rhabdomyolysis (more than other statins at 80 mg).
🔬 Monitoring
LFTs, lipid panel.
💎 Board Pearls
- 🍊 WORST grapefruit interaction — can triple levels (CYP3A4).
- ⚠️ Max 10 mg if on amiodarone/verapamil/diltiazem; max 20 mg if on amlodipine/ranolazine.
- 🌙 Short half-life → take at BEDTIME (when cholesterol synthesis peaks).
Practice Questions
A 74-year-old woman has atrial fibrillation managed on amiodarone 200 mg daily, hypertension managed on amlodipine 10 mg, and newly diagnosed hyperlipidemia. The provider is considering simvastatin (Zocor). Reviewing her chart, what is the maximum daily dose of simvastatin that can be prescribed given her current medication list?
Related Drugs in This Class
- Atorvastatin — Lipitor
- Rosuvastatin — Crestor
Sources
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