An `Amp' by Any Other Name: The Hazards of Intravenous Magnesium Dosing

To the Editor. —  We are aware of three serious instances of hypermagnesemia in the same institution following dosing errors directly related to the availability of vials of magnesium sulfate, each containing 101.5 mmol of magnesium (203 mEq, as 50 mL of a 50% solution).

Report of Cases.—  Case 1.—A 35-year-old man was being treated for alcohol withdrawal. "One amp of 50% magnesium sulfate" was ordered for slow intravenous infusion. The intent was that the patient receive a standard ampule containing 2 mL of 50% solution— 4.03 mmol (1 g or 8.06 mEq) of magnesium. Instead, the patient received a 50-mL vial of 50% magnesium sulfate. After about 35 mL was infused, the patient complained of nausea, vomited, and fell when he attempted to stand. He was noted to have diffuse muscle weakness and areflexia and he could not speak. He was treated with calcium, normal saline, and furosemide. His