What is the recommended approach when switching from simvastatin (Zocor) to rosuvastatin (Crestor)?

Switching from Simvastatin to Rosuvastatin: Recommended Approach

When switching from simvastatin to rosuvastatin, start with rosuvastatin 10 mg daily for most patients, which provides greater LDL-C reduction than simvastatin while maintaining a favorable safety profile. 1

Dosing Equivalence and Conversion

Rosuvastatin is significantly more potent than simvastatin at lowering LDL-C:

• Rosuvastatin 5-10 mg provides approximately 42-49% LDL-C reduction 2
• Simvastatin 20-40 mg provides approximately 37% LDL-C reduction 2

Recommended Conversion:

• Simvastatin 10-20 mg → Rosuvastatin 5 mg
• Simvastatin 40 mg → Rosuvastatin 10 mg
• Simvastatin 80 mg → Rosuvastatin 20 mg

Special Population Considerations

Asian Patients

• Start with a lower dose (5 mg) in Asian patients due to higher rosuvastatin plasma levels compared to non-Asian populations 1
• FDA specifically recommends a lower starting dose (5 mg) in Asian patients 1

Renal Impairment

• For severe renal impairment (CrCl <30 mL/min): start with 5 mg and do not exceed 10 mg daily 3

Drug Interactions

• Avoid gemfibrozil with either statin due to increased risk of myopathy 1
• If using fenofibrate, it can be safely combined with rosuvastatin 1
• For patients on cyclosporine, tacrolimus, or similar immunosuppressants: maximum rosuvastatin dose of 5 mg 3
• For patients on protease inhibitors: rosuvastatin is generally acceptable with appropriate monitoring, but may need to start at a lower dose with certain combinations 1

Timing of Switch

1. Direct switch approach: Discontinue simvastatin and start rosuvastatin the next day at the appropriate equivalent dose
2. No washout period is necessary when switching between these statins
3. Check lipid levels 4-12 weeks after switching to assess efficacy and adjust dosing if needed 1

Monitoring After Switch

• Check liver function tests and creatine kinase at baseline and within 4-12 weeks after switching
• Monitor for muscle symptoms (myalgia, weakness, tenderness)
• For patients with previous statin intolerance, consider every-other-day dosing of rosuvastatin which has shown 34.5% LDL-C reduction with improved tolerability 4

Advantages of Switching

• Rosuvastatin provides greater LDL-C reduction at equivalent doses compared to simvastatin 2, 5
• Rosuvastatin has fewer significant drug interactions than simvastatin 1
• Rosuvastatin is not contraindicated with as many medications as simvastatin 1
• Patients switched from simvastatin 20 mg to rosuvastatin 10 mg show significant improvement in LDL-C goal achievement (86% vs 72%, P<0.0001) 5

Common Pitfalls to Avoid

• Don't use the same milligram dose when switching (rosuvastatin is more potent)
• Don't overlook Asian ethnicity when determining initial dosing
• Don't forget to assess drug interactions that may differ between simvastatin and rosuvastatin
• Don't miss monitoring for muscle symptoms, which can occur with any statin switch

By following these guidelines, the transition from simvastatin to rosuvastatin can be accomplished safely while potentially improving lipid goal achievement and reducing cardiovascular risk.