Co-trimoxazole was recently reported in the BMJ to be associated with an increased risk of sudden death in patients taking angiotensin converting enzyme inhibitors or angiotensin receptor blockers. The results were captured form administrative data bases in Canada. Hyperkalemia is the suspected mechanism. The drug is known to cause hyperkalemia due to potassium sparing diuretic properties of the trimethoprim component, which could act in synergy with ACEs and ARBs to produce severe hyperkalemia.
Via Dr. John M.