Elderly Cotrimoxazole and ACE or ARB Users At Increase Risk For Sudden Death
A new study has concluded that elderly people taking both cotrimoxazole, an antibiotic, and ACE inhibitors or angiotensin-receptor blockers (ARBs) simultaneously are at an increased risk for sudden death.
About The Study
The study was posted on October, 30th 2014 in BMJ by University of Ontario, Toronto Dr. Michael Fralick, Dr. David N Juurlink, and their colleagues.
The study investigated the sudden death side effects of the antibiotics: cotrimoxazole, amoxicillin, ciprofloxacin, norfloxacin, and nitrofurantoin with ACE inhibitors or angiotensin-receptor blockers (ARBs) from 1994 to 2012 in Ontario. The patients were all 66 years of age or older.
According to the authors of the study, the conclusions are independent of sudden death risks such as comorbidities, other medications, recent procedures, and other possibilities.
Results fo the Antibiotic Study
1,027 patients died suddenly seven days after receiving one of the antibiotics.
After the seven day period, cotrimoxazole had the highest incidence rate of sudden death compared to the other antibiotics tested. The increased risk was observed after only two weeks of treatment with cotrimoxazole.
The study showed that patients taking the combination of cotrimoxazole and an ACE or ARB were more than 33 percent more likely to die suddenly than those taking amoxicillion with ACE or ARB. Amoxicillion has shown to pose no risk for sudden death when taken with ARBs or ACE inhibitors.
Cotrimoxazole has been used for decades and is a combination of sulfamethoxazole and trimethoprim. Cotrimoxazole is able to raise serum potassium and, in turn, become lethal as well as cause hyperkalemia, said Dr. Fralick.
The possible risk of hyperlakemia is suspected to be the reason for the sudden deaths. This team has previously found that patients taking cotrimoxazole with ACE or ARBs have a higher chance of being hospitalized due to hyperkalemia.
It is also important to note that a large population of patients has type 2 diabetes or heart problems. These conditions create a higher risk of hyperkalemia and when these patients take the drug combination, their risk would only increase.
Advised Prescribing Methods
Dr. Juurlink, the senior author, advises that doctors prescribe other antibiotics in replacement of cotrimoxazole for patients on ACE or ARBs; however, he also states that this solution is “…not always going to be practical. Alternate strategies could be to use a lower dose or a shorter duration of the drug. Or, when you have to give trimethoprim-based antibiotics to somebody who's on an ACE inhibitor or an ARB, at a minimum being mindful of the potential for serious and even life-threatening hyperkalemia. That alone would go a long way toward reducing the dangers of this interaction.”
Risk can also be minimalized by ensuring a correct dosage and duration of dosage.