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Magnesium Sulfate

Magnesium Sulfate

CLASS

Electrolyte, CNS depressant, Anticonvulsant

DOSAGE

    Eclamptic seizures: 4 gm IV (mixed in 50/100 ml of D5W/NS and administered over 4 minutes). May repeat once at 2 gm IV (mixed in 50/100 ml of D5W/NS and administered over 5 minutes)

    Torsades de pointes and refractory VF: 1-2 gm IV (mixed in 50/100 ml of D5W/NS and administered over 1-2 minutes) followed by a maintenance infusion
    (1 gm in 250 ml of D5W/NS administered at 30-60 gtt/min).

    Asthma Adult: 2 grams in 50/100ml of D5W/NS over 10-20 min.

Pediatric Asthma 20-50 mg/kg in 50/100ml of D5W/NS over 10-20 min

ACTIONS

    Magnesium is an important cofactor for enzymatic reactions and plays an important role in neurochemical transmission and muscular excitability. Magnesium prevents or controls convulsions by blocking neuromuscular transmission and decreasing the amount of acetylcholine liberated at the end plate by the motor nerve impulse. Magnesium is said to have a depressant effect on the central nervous system, but it does not affect the mother, fetus or neonate when used as directed in eclampsia and pre-eclampsia. Magnesium acts peripherally to produce vasodilation.

INDICATIONS

    - Parenteral anticonvulsant for the prevention and control of seizures in severe toxemia of pregnancy.
    - Torsades de pointes.
    - Suspected hypomagnesemic state (eg. chronic alcoholism and chronic use of diuretics).
    - Refractory ventricular fibrillation.
    - Asthma Refracory to other treatment

WARNINGS

    Magnesium Sulfate Injections USP, 50% must be diluted to a concentration of 20% or less prior to IV infusion.
    Because magnesium is removed from the body solely by the kidneys, the drug should be used with caution in patients with renal impairment. Monitoring magnesium serum levels and the patient's clinical status is essential to avoid the consequences of overdose in toxemia. Clinical indications that it is safe to give magnesium include the presence of patellar reflex (knee jerk) and absence of respiratory depression (approximately 16 breaths or more/ minute). Calcium Chloride should be immediately available to counteract the potential hazards of magnesium intoxication in eclampsia.
    Intravenous use of magnesium sulfate should not be given to mothers with toxemia of pregnancy during the two hours immediately preceding delivery.

    SIDE EFFECTS

      Adverse effects of Magnesium Sulfate IV are usually the result of magnesium intoxication. Signs of hypermagnesemia include: flushing, sweating, hypotension, depression of reflexes, flaccid paralysis, hypothermia, circulatory collapse, depression of cardiac function and central nervous system depression. These symptoms can precede fatal paralysis.

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