An essential divalent cation. The major role is as the chelated ion in ATP and presumably other triphosphonucleotides.

The magnesium ATP complex is the sole biologically active form of ATP. The other essential role of magnesium is as the central ion of chlorophyll. Cellular concentration is less than 5mM. Serum concentration approximately 1mM.

Pharmacologic action: Hypomagnesemia can cause refractory ventricular fibrillation or ventricular tachycardia.

Uses: known hypomagnesemic states - suspect hypomagnesmia in alcoholics, chronic disease states, or others with poor nutrition; treatment of choice for Torsade de Pointes.

Dose: 1-2 grams IV push for cardiac arrest, over 1 to 2 minutes for Torsades, and over 5 to 60 minutes for acute myocardial infarction.

Potential complications: Transient flushing and diaphoresis, sinus bradycardia, hypotension, hyporeflexia and paralysis with overdose.

Symbol: Mg

(15 Mar 2000)