Simvastatin to Rosuvastatin Dose Conversion
When converting from simvastatin to rosuvastatin, a simvastatin 40 mg dose is approximately equivalent to rosuvastatin 10 mg in terms of LDL-C lowering effect. 1
Statin Intensity and Equivalence
- Both simvastatin 20-40 mg and rosuvastatin 10 mg are classified as moderate-intensity statins that reduce LDL-C by approximately 30-49% 1
- Rosuvastatin is more potent than simvastatin, with each rosuvastatin dose being equivalent to doses approximately 7-8 times higher for simvastatin in terms of LDL-C reduction 2
- Specific equivalence data shows that rosuvastatin 5 mg reduces LDL-C by 39%, which is comparable to simvastatin 39 mg 2
- Rosuvastatin 10 mg reduces LDL-C by 44%, which would require simvastatin 72 mg to achieve an equivalent reduction 2
Clinical Considerations
- Rosuvastatin 10 mg has been shown to reduce LDL-C by 49% compared to 37% for simvastatin 20 mg in direct comparative studies 3
- When switching from simvastatin to rosuvastatin, consider that rosuvastatin 10 mg achieves NCEP ATP III goals in 86% of patients compared to 64% with simvastatin 20 mg 4
- For patients requiring more intensive lipid lowering, rosuvastatin 20 mg reduces LDL-C by 50%, which cannot be achieved even with the maximum 80 mg dose of simvastatin 2
Safety Considerations
- The FDA no longer recommends initiating or titrating to simvastatin 80 mg due to increased risk of myopathy and rhabdomyolysis 1, 5
- Simvastatin has more drug interactions than rosuvastatin, which may affect the practical equivalence in certain patient populations 1, 5
- For Asian patients, the starting dose of rosuvastatin should be 5 mg daily due to increased plasma concentrations compared to non-Asian populations 6
Special Population Considerations
- For patients with severe renal impairment, the rosuvastatin starting dose should be 5 mg daily and not exceed 10 mg daily 6
- When using rosuvastatin with cyclosporine, the dose should not exceed 5 mg daily 6
- For patients on medications that interact with statins (like amiodarone or ranolazine), rosuvastatin may be a safer alternative than simvastatin 5
Common Pitfalls to Avoid
- Don't use simvastatin 80 mg as an equivalent to rosuvastatin despite potentially similar LDL-C lowering effects, due to FDA warnings against this dose 1, 5
- Don't overlook the need to monitor lipid levels after switching between statins, as individual patient response can vary 1
- Don't forget to consider ethnic differences in statin metabolism, particularly for Asian patients who may require lower rosuvastatin doses 7, 6
- Don't neglect to check for potential drug interactions when switching from simvastatin to rosuvastatin, as the interaction profiles differ 1, 5