Major
diltiazem × Simvastatin
Calcium channel blocker, non-DHP (benzothiazepine derivative)×HMG-CoA reductase inhibitors (statins)
Mechanism
Diltiazem inhibits CYP3A4. Simvastatin concentration rises 2.7-fold. FDA Zocor Section 7 caps simvastatin at 10 mg/day with diltiazem due to myopathy and rhabdomyolysis risk.
Symptoms
Pain in thighs and shoulder girdle, CK above 5× ULN, dark urine.
Management
Cap simvastatin at 10 mg/day. Alternative: pravastatin 40 mg or rosuvastatin 10–20 mg with comparable LDL effect.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.