FDA warnings on use of Simvastatin

Last year, on 8th June 2011, the United State's Food and Drug Administration (FDA) released new warnings about the dangers of high-dose simvastatin, which affects many people. The release also included new warnings about dosing and drug interactions. This article aims to remind us of this warning each time we prescribe this drug.

Simvastatin is a very popular statin, and a generic. It is on all the pharmacy plans. The price point is right and prescribing is hassle free. In 2010, an estimated 2.1 million patients in the USA alone, were prescribed a product containing 80mg simvastatin. Can you imagine how many would have been on it worldwide?

The highlights of the warnings:

1. Restrictions for 80-mg simvastatin
   
   • Avoid prescribing 80-mg simvastatin because of the high risk for myopathy.
   • 80-mg simvastatin is satisfactory if the patient has been on it for a year with no evidence of myopathy.
2. Restrictions for intermediate- and low-dose simvastatin
   
   • No more than 20 mg for patients taking amlodipine and ranolazine
   • No more than 10 mg for patients on amiodarone, verapamil, and diltiazem
3. Restrictions for simvastatin at any dose
   
   • The FDA has mandated drug-labeling changes warning that simvastatin is contraindicated in patients on gemfibrozil, certain antifungal medications (itraconazole, ketoconazole, posaconazole), certain antibiotics (erythromycin, clarithromycin, telithromycin) as well as HIV protease inhibitors, nefazodone, cyclosporine, and danazol.

The information on adverse effects with simvastatin are not new. In 2004, when the A to Z trial was published in JAMA,^[1] an editorial expressed concerns about increased rates of myopathy in patients on simvastatin. The most recent study to cast dispersions on simvastatin was SEARCH, published in The Lancet in 2010.^[2] It linked simvastatin 80mg doses to increased risk for myopathy.

So why didn't the FDA act sooner? That's not clear, but the word is out.

Simvastatin problems are public property. Patients know about them and depend on doctors to clear up their medication regimens. Not all statins are created equal and the least expensive drug may not necessarily be the best for your patient.

References:

1. de Lemos JA, Blazing MA, Wiviott SD, et al; A to Z Investigators. Early intensive vs a delayed conservative simvastatin strategy in patients with acute coronary syndromes: phase Z of the A to Z trial. JAMA. 2004; 292:1307-1316.
2. Study of the Effectiveness of Additional Reductions in Cholesterol and Homocysteine (SEARCH) Collaborative Group, Armitage J, Bowman L, Wallendszus K, et al. Intensive lowering of LDL cholesterol with 80 mg versus 20 mg simvastatin daily in 12,064 survivors of myocardial infarction: a double-blind randomised trial. Lancet. 2010; 376:1658-1669.

Source(s):

1. British Medical Journal. BMJ 2011; 343:d8014