Agranulocytosis and anaemia induced by sulfametopyrazine in a sulfametopyrazine-trimethoprim combination.

We report a case of prolonged fever, agranulocytosis, and anaemia associated with the long acting sulphametopyrazine-trimethoprim combination (Kelfiprim). A woman of 23 years took an overdose of 13 tablets over five days for presumed cystitis. One day after the last dose the patient developed fever and a generalised rash. The fever persisted and her previously normal leukocyte count decreased to 1.8 x 10(9)/1. After treatment with paracetamol the fever settled briefly, and then recurred for another 16 days. A later peripheral blood leukocyte count of 0.77 x 10(9)/1, haemoglobin of 10.8 g/dl, and a hypocellular bone marrow with depressed granulopoiesis and haemopoiesis suggested marrow suppression induced by sulfametopyrazine. Since the IgM antibody against the Epstein-Barr virus capsid antigen was detected, the adverse drug reaction might have been aggravated by this virus. The case highlights the risk of severe haematological adverse reactions associated with sulphonamide treatment, and argues for the use of trimethoprim alone for uncomplicated cystitis.