Pharmacology: Pharmacodynamics: Mechanism of Action: Magnesium Sulfate inhibits convulsion by acting at the myoneural junction to prevent release of acetylcholine and to decrease the motor end plate potential. It inhibits the contraction of the uterus by directly acting on the myometrial cells and enhancing uterine blood flow.
Pharmacokinetics: About one third of orally administered Magnesium Sulfate is absorbed which is enhanced by the presence of the Vitamin D compound Calcitriol. It readily crosses the placenta but rarely causes toxicity to the neonate. Toxicity in the mother is indicated by the loss of patellar reflex, which occurs when the blood level of magnesium is between 7 to 10 mEq/L.