Magnesium sulfate


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO Constipation 5-10 g in 250 mL water. Mild hypomagnesaemia 3 g 6 hrly for 4 doses. IV Hypomagnesaemia Symptomatic deficiency: 1-2 g over 5-60 mins, then maintain at 0.5-1 g/hr if needed. Severe: 1-2 g/hr for 3-6 hr, then 0.5-1 g/hr as needed to correct deficiency. Torsades de pointes W/ pulses: Loading dose: 1-2 g over 5-60 mins, then maintain at 0.5-1 g/hr as needed. Pulseless: 1-2 g over 5-20 mins. Barium poisoning 1-2 g. Cerebral oedema 2.5 g. Eclampsia Loading dose: 4-5 g over 10-15 mins, followed by either a continuous infusion of 1 g/hr or deep IM doses of 4-5 g into alternate buttocks 4 hrly. If seizure recurs, an additional IV dose of 2-4 g may be given. Not to exceed 30-40 g/24 hr. IM Hypomagnesaemia Mild deficiency: 1 g 6 hrly for 4 doses. Severe deficiency: Up to 250 mg/kg w/in 4 hr. Topical Boils and carbuncles Apply as a paste under dressing.
Dosage Details
Intravenous
Reduction of cerebral oedema
Adult: 2.5 g (25 ml of a 10% solution) administered IV.

Intravenous
Torsades de pointes
Adult: With pulses: Loading dose of 1-2 g diluted in 50-100 ml of 5% dextrose inj over 5-60 minutes, followed by maintenance infusion at 0.5-1 g/hr as needed. Pulseless: 1-2 g diluted in 10 ml of 5% dextrose inj and given over 5-20 minutes.

Intravenous
Eclampsia
Adult: Typical loading dose: 4-5 g over 10-15 minutes, followed by either a continuous infusion of 1 g/hr (for at least 24 hr after the last seizure) or deep IM doses of 4-5 g into alternate buttocks every 4 hr (for at least 24 hr after the last seizure). If seizure recurs, an additional IV dose of 2-4 g may be given. Continue therapy until paroxysms cease. A serum magnesium level of 6 mg/100 mL is considered optimal for seizure control. Not to exceed 30-40 g per 24 hr.

Intravenous
Muscle stimulating effects of barium poisoning
Adult: 1-2 g administered IV.

Oral
Constipation
Adult: 5-10 g in 250 mL water.

Oral
Mild hypomagnesaemia
Adult: 3 g every 6 hr for 4 doses.

Parenteral
Hypomagnesaemia
Adult: IM admin: For mild deficiency: 1 g (8.12 mEq or 2 mL of the 50% solution) every 6 hr for 4 doses or based on serum magnesium levels. For severe deficiency: 2 mEq (0.5 mL of the 50% solution)/kg or up to 250 mg/kg within a 4-hr period if needed. IV admin: For symptomatic deficiency: 1-2 g over 5-60 minutes followed by maintenance infusion at 0.5-1 g/hr to correct the deficiency. For severe hypomagnesemia: 1-2 g/hr for 3-6 hr, then 0.5-1 g/hr as needed based on serum magnesium levels.

Topical/Cutaneous
Boils and carbuncles
Adult: Apply as a paste under dressing. Prolonged use is not recommended.
Child: Apply as a paste under dressing. Prolonged use is not recommended.
Renal Impairment
Intravenous:
Reduction of cerebral oedema: Doses should be reduced in renal impairment.
Torsades de pointes: Dose should be reduced in renal impairment.
Eclampsia: In severe renal insufficiency, max dose: 20 g per 48 hr. Regular monitoring of serum magnesium levels is recommended.
Muscle stimulating effects of barium poisoning: Doses should be reduced in renal impairment.
Parenteral:
Dose should be reduced in renal impairment.
Contraindications
Parenteral: Heart block, severe renal impairment, myocardial damage.
Special Precautions
Renal impairment, myasthaenia gravis, digitalised patients; pregnancy. Monitor serum-magnesium concentrations.
Adverse Reactions
Oral: GI irritation, watery diarrhoea. Parenteral: Hypermagnesaemia characterised by nausea, vomiting, flushing, thirst, hypotension, drowsiness, confusion, slurred speech, double vision, bradycardia, muscle weakness. Hypocalcaemia; paralytic ileus.
IM/IV/Parenteral: D
Overdosage
Symptoms of hypermagnesaemia are: respiratory depression and loss of deep tendon reflexes due to neuromuscular blockade; nausea, vomiting, flushing, thirst, hypotension, drowsiness, confusion, slurred speech, double vision, bradycardia and muscle weakness. Treatment in adults should include IV administration of 5-10 mEq of 10% calcium gluconate. Artificial respiration may be required.
Drug Interactions
Oral: Decreases absorption of tetracyclines and biphosphonates. Additive neuromuscular blocking effects with aminoglycosides, digitalis glycosides. Additive effects with nifedipine and CNS depressants.
Action
Description: Oral: Magnesium sulfate increases peristaltic activity by causing osmotic retention of fluids, thus resulting in bowel evacuation. Parenteral: Magnesium sulfate decreases levels of acetylcholine in motor nerve terminals. It also acts on the myocardium by decreasing the rate of SA node impulse formation and prolonging the conduction time.
Onset: Oral: 1-2 hr. IM: 1 hr. IV: Immediate.
Duration: IM: 3-4 hr. IV: 30 min.
Pharmacokinetics:
Absorption: Following administration, 30-50% of the dose is absorbed from the small intestine.
Distribution: Crosses the placenta and small amounts enter the breastmilk. Protein-binding: 25-30%
Excretion: Via urine (absorbed fraction); Via faeces (unabsorbed fraction).
Disclaimer: This information is independently developed by MIMS based on Magnesium sulfate from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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