Dispensing error causing fatal chlorpropamide intoxication in a nondiabetic

A 38-year-old nondiabetic female developed fatal hypoglycemia when chlorpropamide (Diabinese) was accidentally substituted for acetaminophen (Tylenol) with codeine no. 3 in a pharmacy dispensing error. When found, the patient's serum glucose was less than 20 mg/dL. The serum chlorpropamide level on hospital admission was 124 micrograms/mL. The possibility of dispensing error should be considered whenever unexpected drug effects are encountered. In cases of suspected drug overdose, labels and contents of medicine vials found at the scene should be checked for discrepancy.