Objective: Comparison of lipid low-density lipoprotein cholesterol (LDL) levels before and after switching from rosuvastatin or atorvastatin to simvastatin.

Material and Method: The study was a retrospective observational study performed in patients older than 18 year-old who were enrolled as an outpatient at Siriraj Hospital during October 2009 and October 2010. From these patients who were switched from atorvastatin or rosuvastatin to simvastatin, LDL level was compared between before and after switching to simvastatin.

Results: Of 276 patients who were switched from atorvastatin to equivalent dose simvastatin, LDL levels increased from 106.20±33.47 mg/dl to 109.61±39.62 mg/dl (p = 0.089). Of 228 patients who were switched from rosuvastatin to a less than equivalent dose simvastatin, LDL levels increased from 112.73±45.94 mg/dl to 114.49±42.70 mg/dl (p = 0.437).

Conclusion: In the patients who were switched from atorvastatin and rosuvastatin to simvastatin, LDL levels before and after being switched was not significantly different. Moreover, patients who had switched from rosuvastatin to a less than equivalent dose of simvastatin still had no significant increases in LDL levels after switching.

Keywords: Statin, Simvastatin, Atorvastatin, Rosuvastatin, LDL