Magnesium sulfate

Question 1

What is the trade name for magnesium sulfate?

Answer 1

MgSO4

Question 2

What is the drug classification for mag sulfate?

Answer 2

mineral/electrolyte

Question 3

How is magnesium sulfate supplied?

Answer 3

10 % in 2 mL, 5 mL, 8 mL, 10 mL, 20 mL, 30 mL, 50 mL ampules, vials and prefilled syringes

Question 4

Describe the MOA (Pharmacodynamics) of magnesium sulfate.

Answer 4

• Inhibits calcium influx into the cell by acting on cAMP
• As an anticonvulsant it causes relaxation of smooth muscle by interfering with release of acetylcholine and binding with it’s receptors.
• Increases beta2 agonist affinity for it’s receptors and so potentiates it’s effect. Allosteric binding.

Question 5

What are the indications for use of magnesium sulfate?

Answer 5

❑ Refractory ventricular fibrillation/tachycardia with suspected hypomagnesemia (alcoholism, malnutrition or protracted diarrhea)
❑ Polymorphic ventricular tachycardia / Torsades de Pointes
❑ Life threatening ventricular arrhythmias due to digitalis toxicity
❑ Hypomagnesemia
❑ Adjunctive therapy in severe bronchospasm refractory to nebulized medications
❑ Tricyclic Antidepressant (TCA) overdose
❑ Moderate to severe eclampsia symptoms
❑ Preterm Tocolytic – Medical Control

Question 6

What is the dosage of magnesium sulfate in cardiac arrest (Refractory VF/pVT due to hypomagnesaemia or Torsades de Pointes)?

Answer 6

Adult: 1-2 g IVP dilute in 10 mL NS
Pediatric: 20 – 50mg/kg IVP

AHS Adult 2g IV/IO, Pediatric 50mg/Kg IV/IO Max 2g

Question 7

What is the dose of magnesium sulfate for use in Torsades de Pointes with a pulse, Hypomagnesemia, or life threatening ventricular arrhythmias due to digitalis toxicity?

Answer 7

Loading dose: 1 - 2 g IV diluted in 50 ml of NS given over 5 – 60 minutes; Follow with 0.5 – 1 g/hr IV (titrate rate to control torsades).

AHS Polymorphic Vtac/Torsades (with a pulse) - 2g IV/IO diluted in 50mL NS in a buretrol and infuse over 5min

Question 8

What is the dose for magnesium sulfate for use in Bronchospasm / TCA Overdose?

Answer 8

Adult: 1 - 2g IV in 50 ml NS over 10 min
Pediatric: 25 - 50mg/kg IV in 50mL NS over 10min

AHS
Adult 2g IV same dilution/time
Pediatric 25mg/kg to Max 2g in 50mL NS over 20min

Question 9

What is the dose of magnesium sulfate for use in Eclampsia/Tocolytic?

Answer 9

Loading dose: 4 g IV/IO in 50 ml NS over 20 minutes
Maintenance dose: 2 g/Hr in 250 ml NS over 60 min

AHS The same but if seizures are recurrent or ongoing after loading dose, then 2g IV/IO in 50mL NS over 20min and mandatory OLMC

Question 10

What are contraindications to magnesium sulfate use?

Answer 10

• Heart Blocks
• Renal failure
• Pregnant women in actively progressing labor

Question 11

What are precautions to magnesium sulfate usage?

Answer 11

• Moderate doses cause flushing and sweating
• High doses or rapid admin can cause hypotension.
• Hold maintenance dose if patellar reflex absent, depressed respirations, urine output less than 100 ml in preceding 4 hours, or hypotension.

Question 12

What is the antidote for magnesium sulfate toxicity (hypermagnesemia)?

Answer 12

Calcium chloride 1g IV/IO over 10 minutes

*AHS uses Calcium Gluconate, Adult - 3g SIVP/IO, Pediatric - 60mg/kg to Max 3g SIVP/IO (repeat only under OLMC direction)