Iatrogenic magnesium overdose in a patient with suspected acute myocardial infarction.

A case of iatrogenic, parenteral overdose of magnesium sulfate in a patient with suspected acute myocardial infarction is presented. A 73-year-old man presented with a history and physical examination consistent with suspected acute myocardial infarction and congestive heart failure. During the patient's treatment in the emergency department (ED), the physician ordered 2 g magnesium sulfate intravenously. The nurse mistakenly administered "two amps" (two 25-g single-dose vials) of magnesium sulfate intravenously. The patient developed bradycardia, hypotension, and apnea during the infusion. Although the use and inadvertent misuse of magnesium salts in obstetrics is well known, iatrogenic overdose in a patient with cardiac indications for magnesium has not been previously reported. Personnel responsible for the administration of medications in the ED must be educated about the dosing regimens and adverse effects associated with magnesium.