Simvastatin: updated advice on drug interactions

Updated contraindications and maximum dose recommendations when taken with a number of other medicines.

Article date: August 2012

We have previously communicated on the increased risk of myopathy associated with use of high-dose simvastatin (80 mg daily) – see Drug Safety Update May 2010.

Considering the risk of myopathy associated with simvastatin, recent analysis of clinical trial data, spontaneously reported cases and drug- drug interaction studies has resulted in further changes to the simvastatin prescribing information. 

The changes include contraindications to concomitant use with certain medicines and maximum dose recommendations when simvastatin is taken with a number of other medicines, as these interactions may increase plasma concentrations of simvastatin which is associated with an increased risk of myopathy and/or rhabdomyolysis.

Key points to note are that:

  • simvastatin is now contraindicated with ciclosporin, danazol and gemfibrozil
  • the maximum recommended dose for simvastatin in conjunction with amlodipine or diltiazem is now 20 mg/day

A full updated listing of all the interactions is provided in the table below.

Drug interactions associated with increased risk of myopathy/rhabdomyolysis

Interacting agents Prescribing recommendations
HIV protease inhibitors (eg, nelfinavir)
Contraindicated with simvastatin
Other fibrates (except fenofibrate) Do not exceed 10 mg simvastatin daily
Do not exceed 20 mg simvastatin daily
Fusidic acid Patients should be closely monitored. Temporary suspension of simvastatin treatment may be considered.
Grapefruit juice Avoid grapefruit juice when taking simvastatin

Further information

BNF section 2.12: Lipid-regulating drugs 

Article citation: Drug Safety Update August 2012, vol 6, issue 1: S1

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