Chlorpropamide-induced haemolytic anaemia

The mechanisms of sulfonylurea-induced immune hemolysis: case report and review of the literature

Chlorpropamide, a sulfonylurea antidiabetic drug, was found to be the etiologic agent in a patient with immune hemolytic anemia. Hemolysis was severe, and ceased promptly when the drug was discontinued. The direct antiglobulin test was positive for complement, and the indirect antiglobulin test was also positive when the drug, patient serum, and fresh serum complement were all present. In this patient, and in four other patients described in the literature, hemolysis was mediated by the immune complex mechanism. In reports of two other patients taking a sulfonylurea drug, a milder form of hemolysis was mediated by the hapten mechanism. Sulfonylurea drugs are widely used. Since immune complex-mediated hemolysis in these patients is dramatic, it is not likely to be missed. However, the slower, milder hemolysis mediated by the hapten mechanism may be more common than is realized. Such patients may have only mild anemia and a near-normal reticulocyte count, making the diagnosis difficult. It is thus important to consider drug-immune hemolysis in patients who become anemic while taking sulfonylurea drugs.

Chlorpropamide-induced hemolytic anemia

Acute intravascular hemolysis developed when a diabetic patient, previously treated with glyburide, was started on another oral sulfonylurea drug, chlorpropamide. Immunoglobulins were not found in the patient's serum and the red cells were coated with C3 only, suggesting an "innocent bystander" reaction. This case demonstrates that there is no cross reactivity between glyburide and chlorpropamide in producing hemolytic anemia.