Magnesium sulfate 20% & 50% 

Sterile, Clear, Colorless, Concentrated

Injection Solution (IV) or (IM)

Dosage Form

50 ml single dose vial for IV or IM injection


Drug Classification and Categories

Anticonvulsant, electrolyte replacement


Dosage and Administration

Dosage should be individualized according to patient's needs and responses. For intravenous administration, a concentration of 20% or less should be used. 50% solution results in therapeutic plasma levels in 60 minutes, whereas IV doses will provide a therapeutic level almost immediately. The rate of IV injection should not generally exceed 150 mg/minute (1.5 ml of a 10% concentration or its equivalent), except in severe eclampsia with seizures.

Solutions for IV infusion must be diluted to a concentration of 20% or less prior to administration. The diluents commonly used are 5% Dextrose Injection Solution and 0.9% Sodium Chloride Injection. Deep IM injection of the undiluted (50%) solution is appropriate for adults, but the solution should be diluted to a 20% or less concentration prior to such injection in children.

Both IV and IM administration are appropriate.




          •        As a CNS depressant, primarily in preeclampsia and eclampsia of pregnancy


          •        Magnesium sulfate injection is suitable for replacement therapy in magnesium deficiency, especially in acute hypomagnesaemia accompanied by signs of tetany similar to those observed in hypocalcaemia


          •        Acute nephritis (pediatric patients)





Continuous administration of magnesium sulfate beyond 5 to 7 days to pregnant women can lead to hypocalcaemia and bone abnormalities (skeletal demineralization and osteopenia) in the developing fetus.


IV use in eclampsia should be reserved for immediate control of life-threatening convulsions.



Side Effects


Side effects of the solution are due to an increase in the concentration of magnesium in the blood, which occurs with serum concentrations of 4 mEq/L and above, including nausea, vomiting, flushing, sweating, hypotension, slowing of reflexes, flaccid paralysis, decreased body temperature, collapse of blood vessels, hypocalcaemia with tetany, decreased heart function and decreased respiratory output, respiratory arrest and weakening of the central nervous system.





          •        Patients with heart failure or myocardial injury and renal failure.


          •        Women with preeclampsia or eclampsia, this drug should not be administered during the last 2 hours of labor.




Pregnancy Category: D 


          •        Teratogenic Effects:


Magnesium sulfate can cause fetal abnormalities when administered beyond 5 to 7 days to pregnant women. There are retrospective epidemiological studies and case reports documenting fetal abnormalities such as hypocalcaemia, skeletal demineralization, osteopenia and other skeletal abnormalities with continuous maternal administration of magnesium sulfate for more than 5 to 7 days. Magnesium sulfate injection should be used during pregnancy only if clearly needed.


If this drug is used during pregnancy, the woman should be apprised of the potential hazard to the fetus.


          •        Nonteratogenic Effects:


When administered by continuous IV infusion (especially for more than 24 hours preceding delivery) to control convulsions in a toxemic woman, the newborn may show signs of magnesium toxicity, including neuromuscular or respiratory depression




          •        Magnesium sulfate injection (50%) must be diluted to a concentration of 20% or less prior to IV infusion. Rate of administration should be slow and cautious, to avoid producing hypomagnesaemia. The 50% solution also should be diluted to 20% or less for IM injection in infants and children


          •        An injectable calcium salt should be immediately available to counteract the potential hazards of magnesium intoxication in eclampsia.


          •        Count respiration rate for 1 minute every hour. The rate should be ≥ 16


          •        Patella reflexes should be present. Check every hour


          •        Insert an indwelling urinary catheter and measure urinary output hourly. Output should be ≥ 30ml/hour


          •        Geriatric and patients with renal impairment often require reduced dosage because of impaired renal function


Drug Interactions


This drug interacts with CNS depressants, barbiturates, narcotics, neuromuscular blockers, and cardiac digitalis.


Magnesium sulfate precipitates with solutions of high concentrations of alcohol, carbonates and alkaline carbonates, alkali hydroxides, salicylates, strontium, tartrates, phosphates, arsenate, barium and calcium of heavy metals, Procaine hydrochloride, polymyxin B sulfate and clindamycin phosphate. This drug cannot be combined with emulsions containing fat.


Storage Conditions


Store below 30°C and protect from freezing. The solution is clear, colorless and free of suspended particles, otherwise it should not be used.


Discard any unused solution immediately after first use.


From a microbiological point of view, the product should be used immediately. If not used immediately, in-use storage time and conditions prior to use are the responsibility of the user and would normally not be longer than 24 hours at 2 to 8°C, unless dilution has taken place in controlled and validated aseptic conditions.




Each box contains 50 vials with a volume of 50 ml and leaflets.