Magnesium Sulfate injection is primarily indicated for the treatment of hypomagnesemia and conditions related to magnesium deficiency. It is sometimes used to treat irregular heartbeats and may also be used as a laxative. Magnesium Sulfate injection helps correct magnesium deficiency in the body. When administered parenterally, Magnesium Sulfate exhibits anticonvulsant properties and can be used to prevent or control seizures associated with acute uremia, hypothyroidism, and eclampsia. Additionally, it is used in the management of bronchial asthma and cardiovascular disorders.

Magnesium is initially administered either by intravenous infusion or intramuscular injection of Magnesium sulphate. The intramuscular injection is painful. Plasma magnesium concentration should be monitored to determine the rate and duration of infusion, and the dose should be reduced in patients with renal impairment. For intravenous administration, the concentration of magnesium sulphate should not exceed 20%. Dilute 1 part of 50% magnesium sulphate injection with at least 1.5 parts of water for injection.

Eclampsia and Pre-eclampsia: Magnesium sulphate is the drug of choice for preventing recurrent seizures in eclampsia. Initially, give 4 g by intravenous injection over 5–15 minutes, followed by intravenous infusion 1 g/hour for at least 24 hours after the last seizure. If a seizure occurs, give an additional 2 g intravenous injection. Regimens may vary between hospitals. Calcium gluconate injection is used to manage magnesium toxicity.

Arrhythmias: Magnesium sulphate is recommended for emergency treatment of serious arrhythmias, particularly in hypokalaemia or torsades de pointes. Usual dose: 8 mmol Mg²⁺ intravenous injection over 10–15 minutes, repeated if necessary.

Myocardial Infarction: Some studies suggested a reduction in mortality with initial 8 mmol Mg²⁺ intravenous injection over 20 minutes, followed by 65–72 mmol Mg²⁺ infusion over 24 hours, but larger studies have not confirmed this. Some clinicians still consider magnesium beneficial if given immediately for potential reperfusion.

Severe Asthma: Severe asthma may benefit from 1.2–2 g intravenous infusion over 20 minutes.

Hypomagnesaemia: Magnesium is lost in large amounts in gastrointestinal fluids. Excessive losses due to diarrhea, stoma, or fistula are common causes. Deficiency may also occur in alcoholism or as a result of treatment with certain drugs. Hypomagnesaemia often leads to secondary hypocalcaemia, hypokalaemia, and hyponatraemia.

Magnesium is an essential component of many enzyme systems, especially those involved in energy production; the largest stores are found in the skeleton.

• Injection: Each 5 ml ampoule contains a 50% solution of Magnesium sulphate heptahydrate BP (Mg approximately 2 mmol/ml), total 2.47 gm.
• Infusion: Each 100 ml bottle contains a 4% solution of Magnesium sulphate heptahydrate BP (Mg approximately 0.16 mmol/ml), total 4 gm.

Magnesium is the second most abundant cation in intracellular fluids. It is essential for the proper functioning of many enzyme systems and plays a key role in neurochemical transmission and muscle excitability. A deficiency of magnesium is associated with various structural and functional disturbances in the body.

Adult dose

• Intramuscular: For severe hypomagnesemia, 1 to 5 g (2 to 10 mL of 50% solution) daily in divided doses; administration is repeated daily until serum levels have returned to normal. If the deficiency is not severe, 1 g (2 mL of 50% solution) can be given once or twice daily. Serum magnesium levels should serve as a guide to continued dosage.
• Intravenous: 1 to 4 g magnesium sulfate injection may be given intravenously in 10% to 20% solution, but only with great caution; the rate should not exceed 1.5 mL of 10% solution or equivalent per minute until relaxation is obtained.
• Usual Dose Range: 1 to 40 g daily.
• Electrolyte Replenisher: Intramuscular 1 to 2 g in 50% solution four times a day until serum magnesium is within normal limits.

Usual Pediatric Dose

• Intramuscular: 20 to 40 mg per kg of body weight in a 20% solution repeated as necessary.
• For Eclampsia: Initially, 1 to 2 g in 25% or 50% solution is given intramuscularly. Subsequently, 1 g is given every 30 minutes until relief is obtained. The blood pressure should be monitored after each injection.

Use in Children & Adolescents: Magnesium Sulfate seems to be beneficial in the treatment of moderate to severe asthma in children as adjuvant therapy.

With medicine: Magnesium Sulfate may reduce blood pressure when taken together with calcium channel blockers such as nifedipine. The effects of neuromuscular blocking agents may be increased when given with Magnesium Sulfate. When taken together with the following medicines, there may be a risk of respiratory depression: high-dose barbiturates, opioids, and aminoglycoside antibiotics.

With food & others: There is no known interaction of Magnesium Sulfate with food or other substances.

Magnesium Sulfate is contraindicated in patients with defects in the heart’s electrical conduction system that lead to decreased heart function, such as heart block, in cases of severe damage to the heart muscle (myocardium), and in patients with significantly reduced kidney function.

Common: Excessive use of magnesium can lead to hypermagnesemia. Symptoms of hypermagnesemia may include nausea, vomiting, flushed skin, thirst, low blood pressure due to peripheral vasodilation, drowsiness, confusion, and muscle weakness.

Rare: Diarrhea or skin irritation may occur, especially after prolonged exposure or soaking.

Magnesium Sulfate crosses the placenta, so caution is necessary when administering it to pregnant women. It is not known whether the drug is excreted in human milk, and similar caution should be taken when administering it to nursing mothers.

Magnesium salts should be given with caution in patients with impaired kidney function or those receiving digitalis glycosides. Parenteral administration may increase the effects of neuromuscular blocking agents or central nervous system depressants. Blood pressure, respiratory rate, urinary output, and signs of overdose—such as loss of patellar reflex, weakness, nausea, sensation of warmth, skin flushing, drowsiness, double vision, and slurred speech—should be closely monitored.

Symptoms of hypermagnesemia include respiratory depression, loss of deep tendon reflexes due to neuromuscular blockade, nausea, vomiting, flushing, excessive thirst, hypotension, drowsiness, confusion, slurred speech, double vision, slow heart rate (bradycardia), and muscle weakness.

Specific mineral preparations

Store in a cool and dry place. Keep away from light and out of reach of children.