Magnesium Sulfate Flashcards
Magnesium Sulfate Class
Electrolyte, tocolytic
Magnesium Sulfate MOA
Pharmacology: Second most plentiful intracellular cation; essential to enhance intracellular potassium replenishment and activity of many enzymes; important role in neurochemical transmission and muscular excitability (may decrease acetylcholine released by nerve impulses); decreases myocardial irritability and neuromuscular irritability.
Clinical: Cardiac-reduces ventricular irritability, especially when associated with hypomagnesemia; inhibition of muscular excitability.
Magnesium Sulfate Indications
- Torsade de pointes, drug of choice
- Hypomagnesemia
- Pre-term labor (PTL)
- Pregnancy-induced hypertension (PIH, toxemia of pregnancy, pre-eclampsia and/or eclampsia).
- Hyperreactive Airway - Severe Asthma
Magnesium Sulfate Contraindications
- Hypermagnesemia
- Use cautiously in patients with impaired renal function and pre-existing heart blocks (relative).
- Precautions: Caution when used with barbituates, narcotics, or other hypnotics (or system anesthetics) in conjunction with Magnesium Sulfate due to the additive central depressive effects of magnesium.
Magnesium Sulfate Adverse Reactions
- CV: Hypotension (may be transient), flushing, circulatory collapse, depressed cardiac function, heart block, asystole, smooth muscle relaxant (antihypertensive effects).
- Resp: Respiratory depression and/or paralysis. This adverse reaction may occur in both mother and/or infant during or up to 24 hours after the administration of Magnesium Sulfate.
- CNS: Sweating, drowsiness, hypothermia, depressed reflexes progressing to flaccidity and paralysis. This adverse reaction may occur in both mother and/or infant during the administration of or up to 24 hours after the administration of Magnesium Sulfate.
- GI: Nausea
- GU: Mild diuretic
- Meta: Hypocalcemia, hypermagnesemia
Magnesium Sulfate Incompatibilities and Drug Interactions
Concurrent digitalization increases danger of dysrhythmias
Magnesium Sulfate Adult Dosage
Cardiac:
• Torsade de pointes: 1-2 Gm IV diluted in 50-100 ml NS or D5W administered over 1-2 minutes, followed by the same amount infused over 1 hour.
• Hypomagnesemia: Dilute 1-2 Gm in 50-100 ml NS or D5W administered IV push over 5-60 minutes.
• Respiratory/Severe Asthma: Initial Infusion (field) 2 Gm Magnesium Sulfate mixed in 50 ml NS or D5W to be infused IV using microdrip tubing over 5 to 10 minutes. Stop infusion if hypotension, respiratory depression or bradycardia develop.
Pregnancy:
Pre-term labor (PTL): Initial bolus (Field and Interfacility): 4-6 Gm over 15-20 minutes (Suggested method is the addition of 4 Gm to 100 ml D5W, LR or NS. Resultant concentration is 40 mg/ml.) Maintenance Infusion (Interfacility only): 1-4 Gm/hour infusion rate. (Suggested method for treatment of premature labor is to follow initial bolus with infusion of 2 Gm/hr which may be continued until uterine contractions are reduced to < 1 every 10 minutes. Then, infusion is decreased to 1 Gm/hr and continued for 24-72 hrs. One method for mixing infusion is the addition of 40 Gm to 1000 ml LR. Resultant concentration equals 40 mg/ml. If this concentration is run at 50 ml/hr, Magnesium Sulfate delivered equals 2 Gm/hr).
Pregnancy induced hypertension, pre-eclampsia/eclampsia, (PIH): Initial bolus (Field and Interfacility): 3-6 Gm over 10-15 minutes (Suggested method is the addition of 4 Gm to 100 ml D5W, LR or NS. Resultant concentration is 40 mg/ml). Maintenance Infusion (Interfacility only): Follow bolus with 1-3 Gm/hour infusion rate. (Same mixture as for PTL). Rebolus: In an eclamptic emergency may rebolus with Magnesium Sulfate, 2-4 Gm depending on patient size (mixed as an initial bolus) over 10-15 minutes if respirations >12/minute and urine output >30 ml/hr.
Magnesium Sulfate Pediatric Dosage
N/A
Magnesium Sulfate Routes
IV infusion, IO
Magnesium Sulfate Onset
Seconds, 20 minutes for infusion
Magnesium Sulfate Peak Effects
Not known
Magnesium Sulfate Duration
24 hours or greater
Magnesium Sulfate AZ Drug Box Minimum
5 g
