Study finds commonly co-prescribed drugs can cause serious side effects, including muscle breakdown and kidney injury

Patients taking certain statins to lower cholesterol are at an increased risk of hospitalization if they are also prescribed antibiotics to treat a respiratory tract infection, such as a sinus infection or pneumonia. In a new study, researchers at Lawson Health Research Institute (Lawson) and the Institute for Clinical Evaluative Sciences (ICES) found that when certain statins (atorvastatin, simvastatin and lovastatin) are taken in conjunction with antibiotics known as macrolides (clarithromycin and erythromycin), these drugs combined can increase the risk of rhabdomyolysis (breakdown of muscle fibres) and acute kidney failure. Some of these reactions may be fatal.

The study is the first of its kind to look at the interaction between statins and antibiotics using real-world data. Previous clinical studies on this drug-drug interaction have been done in a regulated setting, excluding patients at highest risk for serious side effects. In some studies, levels of statin in the blood increased 10-fold among patients taking macrolide antibiotics.

The researchers looked at hospital data from 2003 to 2010 for over 75,000 Ontario residents 65 years of age or older who were prescribed a statin and a macrolide antibiotic (either clarithromycin or erythromycin). They then looked for hospital admissions within 30 days of antibiotic prescription for incidence of side effects. During the 7-year study period, hundreds of hospital admissions with acute kidney injury and deaths were associated with this drug-drug interaction.

“Statins are the number one class of drugs prescribed in North America. Co-prescription of a statin with a macrolide antibiotic is very common,” says Dr. Amit Garg, a researcher at Lawson and ICES, a kidney specialist at the London Health Sciences Centre (LHSC), and a Professor of Medicine and Epidemiology at Western University. “Until now, the clinical and population-based consequences of this potential drug-drug interaction were unknown.”

The researchers looked at laboratory data from 12 regional hospitals. “While hundreds of hospitalizations in Ontario alone are associated with this drug-drug interaction, it is preventable,” says Dr. Amit Patel, an internal medicine resident at LHSC and ICES and co-author of the study. “The results provide important safety information regarding these commonly prescribed medications.”

Dr. Patel suggests physicians consider alternatives when co-prescribing these drugs. “When prescribing clarithromycin or erythromycin to patients on these statins, preventative measures should be considered, such as cessation of the statin for the duration of the antibiotic therapy, increased monitoring for adverse events or use of a different antibiotic that does not interact with these statins.”

“Statin Toxicity from Macrolide Antibiotic Co-Prescription: A Population-Based Study of Older Adults” appears in the current issue of Annals of Internal Medicine.

Lawson Health Research Institute. As the research institute of London Health Sciences Centre and St. Joseph's Healthcare London, and working in partnership with Western University, Lawson Health Research Institute is committed to furthering scientific knowledge to advance healthcare around the world. www.lawsonresearch.com

ICES is an independent, non-profit organization that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.

This work was done by the new provincial ICES Kidney, Dialysis and Transplantation Research Program.

FOR MORE INFORMATION PLEASE CONTACT:

• Julia Capaldi
• Communications & Public Relations, Lawson Health Research Institute
• [email protected]
• (w) 519-685-8500 ext. 75616 or (c) 519-200-1115

• Deborah Creatura
• Communications, ICES
• [email protected]
• (o) 416-480-4780