Allergic reaction to nafamostat mesilate in hemodialysis patients

Nafamostat mesilate (NM), a serine-protease inhibitor, is widely used in Japan as an anticoagulant for extracorporeal circulation in patients on hemodialysis with high risk of bleeding. Between 1999 and 2002 we encountered eleven patients (6 males and 5 females; 65±6 years old) who presented with allergic reaction to this drug; 4 cases of shock, 4 of high fever and 3 of severe systemic eruption. All had been on maintenance hemodialysis for 8±6 years (between 0 and 23 years). All patients had received this drug more than once before the occurrence of allergy. Most of these patients (91%) had a previous history of drug allergy. However, among these cases, there was no specific tendency found in the duration of maintenance dialysis, cause of renal failure or category of dialyser. Shock was always observed within 15 minutes from the start of dialysis, and high fever occurred either during dialysis or 6 hours after therapy. None of the patients exhibited any allergic reaction after cessation of NM and there were no pesistent sequelae. Among laboratory findings, eosinophilia was found in 6 among 8 cases measured, but no other laboratory test was diagnostic. Among previously reported cases of NM allergy, there is no typical pattern in the duration of maintenance dialysis, causes of renal failure or category of dialyser. Most cases demonstrated allergic reaction at the second or later NM administration except for one case developing circulatory shock after the first administration. This reaction may develop after being immunized against the drug. There is not yet any useful tool to predict the incidence. Caution with regard to allergy is necessary whenever NM is used as a dialysis anticoagulant.