Statins and drug interactions
January 11th, 2008
Care needed when taking statins with other drugs
The Medicines and Healthcare products Regulatory Agency (MHRA) has recently reminded doctors of the impact of drug interactions with the use of statins. These apply particularly to simvastatin and less so to atorvastatin as they are inducers of a particular cytochrome enzyme system called the CYP3A.
Simvastatin (Zocor) and Atorvastatin (Lipitor)
Particular care has to be taken with simvastatin if the following drugs are used - ketoconazole, itraconazole, erythromycin, clarithromycin, and HIV protease inhibitors. Grapefruit juice but not grapefruit flesh should be avoided with simvastatin. Reduced doses of atorvastatin are needed when these drugs are used in combination with it.
Rosuvastatin (Crestor)
Care must be taken with antacids and HIV protease inhibitors when used with rosuvastatin.
All statins
Other drugs requiring care when used with statins include warfarin, cyclosporin, verapamil, amiodarone, diltiazem and danazol. Most statins will effect warfarin action particularly fluvastatin but rosuvastatin and pravastatin are less implicated. Statins are often used with ezetimibe and fibrate and greater care regarding safety needs to be taken when these are used in combination.
Some drugs, such as rifampicin used as a treatment in tuberculosis, may reduce plasma concentrations of simvastatin and atorvastatin making them less effective.
© Dr Abraham, January 2008
