Co-trimoxazole and sudden death in patients receiving inhibitors of the renin-angiotensin system

A study shows that co-trimoxazole is associated with an increased risk of sudden death in patients taking ACE inhibitors or ARBs.

Read the full research: bmj.com/content/349/bmj.g6196 Angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) are among the most commonly prescribed drugs in clinical practice. Each year, more than 50 million prescriptions are dispensed in the United Kingdom and more than 250 million prescriptions in the United States. Both drug classes increase the risk of hyperkalemia, which occurs in up to 10% of patients and is particularly common in patients with other drug and disease related risk factors for hyperkalemia. Co-trimoxazole (a combination antibiotic containing trimethoprim and sulfamethoxazole) is commonly prescribed for the treatment of urinary tract infection and is listed on the World Health Organization’s essential medicines list. Each year, approximately five million prescriptions are dispensed in the United Kingdom and 20 million in the United States. Approximately 80% of patients receiving co-trimoxazole develop increases in serum potassium concentrations and 6% develop frank hyperkalemia. In this research, the scientists set out to determine whether the prescription of co-trimoxazole with an ACE inhibitor or ARB is associated with sudden death. They found that in older patients there is an associated increased risk of sudden death. Unrecognized severe hyperkalemia may underlie this finding. When appropriate, alternative antibiotics should be considered in such patients.