Two reports describe serious hyperkalaemia, apparently caused by the concurrent use of
trimethoprim and enalapril or quinapril, in association with
renal impairment.
Trimethoprim or
ACE inhibitors alone can cause hyperkalaemia, particularly with other factors such as
renal impairment. Monitor potassium levels if this combin- ation is used in those with
renal impairment. Note that
co-trimoxazole is a combination preparation containing
trimethoprim, and may therefore interact similarly. It has been suggested that patients with
AIDS taking an ACE inhibitor for associated nephropathy should probably discontinue this treatment during treatment with high-dose
co-trimoxazole.