Magnesium Action: .Co-factor in Na-K membrane pump. A decrease in Mg leads to a decrease in intracellular potassium. Indication: Used for SVT, VT, Torsade de pointes and digitalis-induced arrhythmia. It is impossible to adequately replace intracellular potassium in the presence of hypomagnesaemia. Chronic Magnesium deficiency usually due to diuretics, aminoglycosides, alcohol abuse, secondary aldosteronism, and malabsorption. Side Effects: Flushing and nausea in 10% of patients during bolus administration. Transient hypotension that may be treated with IV fluid or small doses of calcium. Contraindications: Renal failure. Heart block and bradycardia. Precautions: Serum magnesium levels do not reflect intracellular levels (1% extracellular) and total body depletion of magnesium may be present despite of normal serum levels.