From the Guidelines
Magnesium sulfate has several important medical uses beyond treating asthma, including preventing and treating seizures in pregnant women with preeclampsia or eclampsia, as a tocolytic to delay preterm labor, and treating certain cardiac arrhythmias, particularly torsades de pointes. The medication is commonly used to prevent and treat seizures in pregnant women with preeclampsia or eclampsia, typically administered intravenously at 4-6 grams loading dose followed by 1-2 grams per hour maintenance, as recommended by recent guidelines 1. For severe hypomagnesemia, it can be given at 1-2 grams IV over 5-60 minutes depending on severity. The medication is also used as a tocolytic to delay preterm labor, administered as 4-6 grams IV loading dose followed by 1-2 grams per hour maintenance for up to 48 hours. Additionally, magnesium sulfate treats certain cardiac arrhythmias, particularly torsades de pointes, given as 1-2 grams IV over 5-20 minutes, as supported by studies such as 1. It's also used as a laxative orally or as an enema for constipation, and topically in Epsom salt baths for muscle soreness. Magnesium sulfate works by blocking calcium channels, relaxing smooth muscle, stabilizing cell membranes, and acting as an NMDA receptor antagonist to prevent seizures. Some key points to consider when using magnesium sulfate include:
- Monitoring for signs of magnesium toxicity including respiratory depression, hypotension, and loss of deep tendon reflexes when receiving IV administration.
- The duration of MgSO4 use postpartum remains contentious, but continuing MgSO4 for 24 hours postpartum is a reasonable approach, as suggested by 1.
- Each unit should develop their own protocols for postpartum magnesium, taking into consideration the known incidence of eclampsia postpartum. Overall, magnesium sulfate is a versatile medication with various uses beyond treating asthma, and its administration should be guided by the most recent and highest-quality evidence, prioritizing patient safety and outcomes.
From the FDA Drug Label
In counteracting the muscle-stimulating effects of barium poisoning, the usual dose of magnesium sulfate is 1 to 2 g given IV. For controlling seizures associated with epilepsy, glomerulonephritis or hypothyroidism, the usual adult dose is 1 g administered IM or IV In paroxysmal atrial tachycardia, magnesium should be used only if simpler measures have failed and there is no evidence of myocardial damage. The usual dose is 3 to 4 g (30 to 40 mL of a 10% solution) administered IV over 30 seconds with extreme caution. For reduction of cerebral edema, 2. 5 g (25 mL of a 10% solution) is given IV.
Other medical uses of magnesium sulfate include:
- Counteracting the muscle-stimulating effects of barium poisoning
- Controlling seizures associated with:
- Epilepsy
- Glomerulonephritis
- Hypothyroidism
- Treatment of paroxysmal atrial tachycardia
- Reduction of cerebral edema 2 2
From the Research
Medical Uses of Magnesium Sulfate
Magnesium sulfate has several medical uses beyond treating asthma, including:
- Treatment of hyper-tension and seizures associated with eclampsia of pregnancy 3
- Use as a tocolytic agent to prevent preterm labor 3
- Treatment of preeclampsia and eclampsia 4
- Treatment of myocardial infarction and cardiac arrhythmias 4
- Treatment of severe acute asthma in children and adults, particularly in cases where patients do not respond to initial treatment with bronchodilators and systemic corticosteroids 5, 6, 7
Specific Applications
Some specific applications of magnesium sulfate include:
- Intravenous administration to reduce admissions and improve pulmonary function in severe asthma exacerbations 5
- Use as a bronchodilator, although its effectiveness is less convincing compared to other treatments like salbutamol 5
- Potential benefit in chronic asthma management, although the evidence is still limited 5
- Treatment of acute severe asthma in children, with reported effectiveness and safety in this population 6