Magnesium Sulfate

Electrolyte

Reduces striated muscle contractions and blocks peripheral nueromuscular transmission by reducing acetylcholine release at the myoneural junction, manages seizures in toxemia of pregnancy, induces uterine relaxation, can cause bronchodilation after beta-agonists and anticholinergics have been used.

Seizures of eclampsia (toxemia of pregnancy), torsade de pointes, hypomagnesemia, class IIa agent for V-fib/pulseless V-tach that is refractory to lidocaine.

Heart Blocks, myocardial damage

CNS depression, facial flushing, diaphoresis, depressed reflexes, circulatory collapse, hypotension.

May enhance effects of CNS depressants, serious changes in overall cardiac function may occur with cardiac glycosides

10%, 12.5%, 50% solution in 40, 80, 100 and 125mg/mL

• Adult: Seizure activity associated with pregnancy: 1-4g IV/IO over 3 min; max dose of 30-40 g/day. Cardiac arrest due to hypomagnesemia or torsades de pointes: 1-2 g (2-4mL of a 50% solution) diluted in 10 mL of D₅W IV/IO over 5-20 min. Torsades de pointes with a pulse or AMI with hypomagnesemia: Loading dose of 1-2 g mixedd in 50-100mL D₅W over 5-60 min. IV. Follow with 0.5-1 g/hr IV (titrate to control torsades de pointes).
• Pediatric: For asthma:25-50 mg/kg (maximum dose 2 g) over 10-20 min.

• Onset: IV/IO: immediate, IM 3-4 hours
• Duration: IV/IO: 30 min., IM 3-4 hours

Pregnancy safety: Category B. Recommended that the drug not be given in the 2 hours before delivery, if possible. IV calcium chloride or calcium gluconate should be available as a magnesium antagonist if needed. Use with caution in Pts. with renal failure.