Magnesium Sulfate Injection, USP is suitable for replacement therapy in magnesium deficiency, especially in acute hypomagnesemia accompanied by signs of tetany similar to those observed in hypocalcemia. In such cases, the serum magnesium (Mg++) level is usually below the lower limit of normal (1.5 to 2.5 mEq/liter) and the serum calcium (Ca++) level is normal (4.3 to 5.3 mEq/liter) or elevated. In total parenteral nutrition (TPN), magnesium sulfate may be added to the nutrient admixture to correct or prevent hypomagnesemia which can arise during the course of therapy. Magnesium Sulfate Injection, USP is also indicated as a parenteral anticonvulsant for the prevention and control of seizures (convulsions) in severe toxemia of pregnancy. It effectively prevents and controls the convulsions of eclampsia without producing deleterious depression of the central nervous system of the mother or infant. However, other effective drugs are available for this purpose. Magnesium Sulfate Injection, USP may be used to control hypertension, encephalopathy and convulsions associated with acute nephritis in children. However, other drugs such as barbiturates, reserpine or hydralazine should be tried first.