Magnesium Sulfate (MgS04)

CLASSES:

• Electrolyte • Antiarrhythmic • CNS depressant • Anticonvulsant

ACTIONS:

• For treatment of seizures due to toxemia of pregnancy by decreasing neuronal excitability (anticonvulsant)

• Blocks the neuromuscular transmission and the amount of ACh released at the motor end plate.

• May result in relaxation of bronchial and vascular smooth muscle which is probably secondary to calcium blockade

INDICATIONS:

• Refractory VF/VT

• Torsades de pointes

• Refractory seizures related to hypomagnesemia especially in alcoholics

• Eclampsia

• Hyper-reflexia of toxemia of pregnancy (pre-eclampsia)

• Cardiac arrhythmias due to dig toxicity

• Controversial: refractory bronchospasm not responsive to beta agonist, steroids, aminophylline

CONTRAINDICATION:

• Heart blocks , controversy in acute MI patient

STANDARD PREP:

• 1 gm/2 ml

DOSAGE/ROUTE:

• For acute administration during VT, 1 or 2 g of magnesium sulfate in 10 cc over 1 to 2 minutes

• In VF should be given IV push — Follow up infusion of 0.5 - 1.0 g/hr for 24 hr

• Torsades = 2.0 g IV bolus, followed by 2nd 2.0 g bolus

  If no response, followed by infusion

• Anticonvulsant = 1-4 g IV over 30 minutes, or more rapidly if seizing (over 5 minutes)

SIDE EFFECTS:

• Hypotension

• Bradycardia

• Flushing

• Hypermagnesemia may produce depressed reflexes (patella), flaccid paralysis, circulatory collapse, respiratory depression or paralysis, and diarrhea.

PRECAUTIONS:

• Monitor respiratory rate because respiratory depression is a serious side effect of hypermagnesemia.

• IV Calcium Chloride should be available as an antagonist.

• Concurrent use with CNS depressant requires lower dosage adjustments

• Monitor EKG

• Use with caution in renal failure patients