Beware of combining erythromycin with a statin.

To the Editor: For the first time in 40 years as a scientist, I have information I believe is so important that I want to share it immediately with as many people as possible. The medical community and the public need to know about the increased risk of cataracts associated with concurrent use of the common antibiotic erythromycin and cholesterol-lowering statins. Among the most prescribed drugs in the United States, statins work by inhibiting cholesterol biosynthesis. The review of patient records at the University Hospital of Basel, Switzerland, by Christopher Meier, PhD, MSc,1 and our studies with animals at the Kirksville College of Osteopathic Medicine2 indicate that brief exposure to high blood levels of statins can markedly increase the risk of cataracts in humans and animals. Results of the casecontrolled analysis by Schlienger et al,1 revealed that a single course of erythromycin therapy combined with simvastatin doubled the risk for cataracts and that two courses of erythromycin with simvastatin tripled the risk for cataracts. Erythromycin can block the metabolism of many statins and vastly increase blood levels of cholesterol-lowering drugs. In January 2003, we reported that treatment of a specific strain of rats (Chbb: Thom) with a high dose of simvastatin for 2 weeks committed the ocular lens to forming cataracts.2 We believe this strain of rat has a defect in regulating one of the key enzymes in cholesterol biosynthesis that prevents it from defending against stress caused by high blood levels of simvastatin. Combining drugs other than erythromycin with statins may also place the eye at increased risk. These drugs include verapamil hydrocholoride, cyclosporine, itraconazole, and ketoconazole. Each drug can inhibit the metabolism of simvastatin, atorvastatin calcium, cerivastatin and lovastatin by the cytochrome P450 system. Therefore, great care should be taken when combining any of these drugs with statins.