Risk of anaphylaxis after reexposure to intravenous lepirudin in patients with current or past heparin-induced thrombocytopenia

OBJECTIVE: To retrospectively assess the signs and symptoms indicative of adverse reactions to repeated exposures to lepirudin in patients with heparin-induced thrombocytopenia who received at least 2 courses of lepirudin therapy. PATIENTS AND METHODS: Medical records were retrospectively assessed from adult patients who received at least 2 courses of lepirudin therapy separated by at least 1 week between January 1999 and June 2002 at The Cleveland Clinic, Cleveland, Ohio. We evaluated the list of 289 low-level terms for possible signs and symptoms of anaphylactic reactions in the medical dictionary for regulatory activities as well as patient vital signs to detect manifestations of immediate hypersensitivity reactions. Vital signs from the day before initiation of lepirudin therapy were compared with those from days 1 and 2 after exposure. RESULTS: No cases of anaphylaxis or allergic reaction related to lepirudin administration were identified among 43 adult patients. On day 1 of lepirudin, 10 patients had lower systolic blood pressures (by >= 20 mm Hg) than pre-lepirudin values, and 4 patients had systolic blood pressures of less than 100 mm Hg. CONCLUSIONS: Isolated asymptomatic decreases in blood pressure after patient reexposure to lepirudin most likely do not reflect anaphylaxis due to lepirudin. We believe that isolated and uncommon cases of anaphylaxis temporally related to lepirudin exposure should not preclude its use in patients with heparin-induced thrombocytopenia and past lepirudin exposure.