Combining the antibiotic clarithromycin with some statins increases the risk of adverse events, which may lead to hospital admission in older patients, according to Canadian researchers.
The authors of a new study, published in the Canadian Medical Association Journal, note that rosuvastatin and pravastatin are metabolized differently than other types of statins.
“To prevent toxicity, the use of azithromycin or another antibiotic that does not interact with statins can be considered”
The researchers compared the use of two common antibiotics, clarithromycin and azithromycin, in older adults who were also taking rosuvastatin, pravastatin or fluvastatin to determine if adverse events occurred.
They looked at data on 104,041 statin users aged 66 or over in Ontario who also had a prescription for one of the antibiotics – 51,523 for clarithromycin and 52,518 for azithromycin.
Co-prescription of clarithromycin and a statin was associated with a modest increase in the number of deaths and hospital admissions for acute kidney injury or high potassium levels.
“The absolute increase in risk for each outcome was small and likely below 1%,” said the authors, but they highlighted that it was statistically significant.
They suggested the adverse events may reflect statin toxicity among older adults.
The findings are at odds with traditional thinking that these types of statin are safer than others and not as likely to be affected by other medications.
“Our findings indicate that unintended adverse events may still occur, possibly because of [other metabolic pathways],” said the authors.
“To prevent toxicity, the use of azithromycin or another antibiotic that does not interact with statins can be considered,” they added.