Sudden death and a common antibiotic

The longer I practice medicine, the more nervous I get about medications, especially when patients are already on other drugs for chronic diseases. I much prefer deprescribing.
A recent study on the common antibiotic cotrimoxazole, which is a combination of sulfamethoxazole and trimethoprim, and often referred to by its brand name, Bactrim or Septra, lends credence to the notion that combining drugs can be dangerous.
In a large case control study of more than 1.6 million patients over 17 years, researchers from Canada found that cotrimoxazole was associated with a three-fold increased risk of sudden death when used in older patients (age > 66) taking angiotensin converting enzyme (ACE) inhibitors or angiotensin blockers (ARBs).
Steve Stiles covered the research on theHeart.org. Here is a link to the full article in the British Medical Journal. (A side note: The authors wrote the paper in the active voice. It was a pleasure to read.)
The Canadian researchers argue the association was plausible, and that the likely mechanism of sudden death involved high potassium levels (hyperkalemia). Their findings provide important messages to caregivers and patients alike.
Comments:
In a general sense, this study gives me pause because cotrimoxazole carries such a benign reputation. “Go ahead and just cover him with some Bactrim. How can it hurt?” goes the (fast) thinking.
And be honest; did you know trimethoprim blocks the epithelial sodium channel (ENaC) in the distal nephron,...

Source: Dr John M - November 12, 2014 Category: Cardiology Authors: Dr John Source Type: blogs