magnesium sulfate (injection) (cont.)

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PREPARATIONS: Intramuscular magnesium sulfate available in 500 mg/ml strength, in 2 ml, 10 ml, and 50 ml single-use vials.

Intravenous magnesium sulfate is available in 40mg/ml and 80mg/ml strengths. 40 mg/ml concentration is available in 50 ml, 100 ml, 500 ml, and 1000 ml single-dose, plastic containers. 80 mg/ml concentration is available in 50 ml partial-fill, single-dose, flexible plastic container.

STORAGE: Intramuscular magnesium sulfate injections are stored between 15 C to 30 C (59 F to 86 F). Intravenous magnesium sulfate injections are stored between 20 C to 25 C (68 F to 77 F).




  • Mild: Inject 1 gram intramuscularly (IM) every 6 hours for 4 doses.
  • Severe: 5 grams administered intravenously (IV) over 3 hours.
  • Maintenance: 30-60 mg/kg/day IV.

Seizure with eclampsia or pre-eclampsia: 4-5 grams IV and undiluted IM injection of up to 10 grams (5 grams into each buttock) simultaneously.

Torsades de Pointes: 1-2 grams IV administered over 5 to 60 minutes.


Hypomagnesemia: 25-50 mg/kg IV or IM every 4 to 6 hours, for 3 to 4 doses, as needed.

DRUG INTERACTIONS: Barbiturates, narcotics or other hypnotics or other drugs that slow brain function may add to the brain depressing effects of magnesium. Magnesium adds to the effect of neuromuscular blocking agents.

Magnesium sulfate should be administered with extreme caution in patients receiving digoxin (Lanoxin) due to the risk of abnormal heart beats.

PREGNANCY: Magnesium sulfate can cause fetal abnormalities, such as hypocalcemia, skeletal demineralization, osteopenia and other skeletal abnormalities, when administered beyond 5-7 days to pregnant women. It should be used only if clearly needed. If magnesium sulfate needs to be used during pregnancy, the woman should be informed of the potential risks to the newborn.

NURSING MOTHERS: Magnesium sulfate enters breast milk therefore, it is best to be cautious before using it in nursing mothers.

Medically reviewed by Eni Williams, PharmD


FDA Prescribing Information.

Medscape. magnesium sulfate (Rx).

Medically Reviewed by a Doctor on 3/19/2015

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