MAGNESIUM SULFATE IN DEXTROSE 5% IN PLASTIC CONTAINER

Clinical safety rating: caution

Comprehensive clinical and safety monograph for MAGNESIUM SULFATE IN DEXTROSE 5% IN PLASTIC CONTAINER (MAGNESIUM SULFATE IN DEXTROSE 5% IN PLASTIC CONTAINER).

How it works

Magnesium sulfate provides magnesium ions, which are essential for various physiological processes. It acts as a cofactor for enzymatic reactions, stabilizes excitable membranes, and antagonizes calcium entry at the neuromuscular junction, leading to reduced acetylcholine release and muscle relaxation. In the CNS, it may act as a noncompetitive antagonist of NMDA receptors, exerting anticonvulsant effects.

What the body does with it

Metabolism	Magnesium is not metabolized; it is primarily excreted unchanged by the kidneys via glomerular filtration and tubular reabsorption. Elimination half-life is approximately 4-6 hours in normal renal function.
Excretion	Primarily renal (90-100% as unchanged magnesium). Less than 1% biliary/fecal.
Half-life	Terminal half-life approximately 4-5 hours in normal renal function; prolonged in renal impairment (up to 40 hours).
Protein binding	Approximately 25-30% bound to albumin.
Volume of Distribution	0.2-0.3 L/kg; distributes primarily in extracellular fluid.
Bioavailability	IV: 100%. Not administered orally for systemic effect due to poor GI absorption (<30%).
Onset of Action	IV: immediate (within seconds to minutes).
Duration of Action	IV: 30 minutes (anticonvulsant effect); continuous infusion required for sustained effect.

Classification & Brands

Dosing & administration

1 to 4 g intravenously as a 5% to 20% solution, rate not exceeding 150 mg/min; dosing frequency depends on indication (e.g., preeclampsia/eclampsia: 4-5 g IV loading then 1-2 g/hr infusion; hypomagnesemia: 1-2 g IV over 1-2 hours, may repeat based on serum magnesium levels).

Dosage form	INJECTABLE
Renal impairment	GFR 30-50 mL/min: reduce dose by 50% and monitor serum magnesium; GFR <30 mL/min: contraindicated or use extreme caution with dose reduction to 25% of normal and frequent monitoring.
Liver impairment	Child-Pugh A (mild): no specific adjustment; Child-Pugh B (moderate): use with caution, consider dose reduction; Child-Pugh C (severe): avoid use or reduce dose by 50% with close monitoring of magnesium levels and renal function.
Pediatric use	Loading dose: 20-40 mg/kg intravenously over 1-2 hours; maintenance: 10-20 mg/kg IV every 4-6 hours as needed; maximum infusion rate 150 mg/min; monitor serum magnesium during therapy.
Geriatric use	Reduce initial dose by 25-50% due to age-related decline in renal function; monitor serum magnesium and renal function closely; adjust dose based on GFR and clinical response.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for MAGNESIUM SULFATE IN DEXTROSE 5% IN PLASTIC CONTAINER (MAGNESIUM SULFATE IN DEXTROSE 5% IN PLASTIC CONTAINER).

Breastfeeding	Magnesium sulfate is excreted into breast milk in low amounts; M/P ratio approximately 0.2-0.3. Usually compatible with breastfeeding but monitor infant for hypotonia, lethargy, or feeding difficulties if high maternal doses are used long-term.
Teratogenic Risk	Magnesium sulfate crosses the placenta and is not associated with major teratogenic effects when used for standard obstetric indications. Prolonged exposure (e.g., >5-7 days) in the second/third trimester may cause fetal hypocalcemia, skeletal abnormalities, or neonatal hypotonia. Continuous infusion near delivery may lead to neonatal respiratory depression and flaccidity.

Warnings & precautions

■ FDA Black Box Warning

WARNING: Do not administer undiluted intravenously. Continuous monitoring of serum magnesium levels, respiratory rate, deep tendon reflexes, and urine output is required. Hazardous infusion rates may cause respiratory arrest, cardiac arrest, or death.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to magnesium sulfate or any component of the formulation","Myocardial damage or heart block (unless used for torsades de pointes)","Severe renal impairment (anuria or oliguria) without dialysis","Comatose patients (unless for seizure control)","Absence of deep tendon reflexes (sign of hypermagnesemia)"]

Clinical Precautions

Precautions

["May cause respiratory depression or arrest if given too rapidly or in excessive doses.","Use with caution in patients with renal impairment due to risk of accumulation and toxicity.","Administer IV with caution in patients receiving digitalis glycosides; may cause heart block.","Monitor deep tendon reflexes, respiratory rate, and urine output during infusion.","Avoid concurrent use of neuromuscular blocking agents; may potentiate blockade.","Use with caution in patients with myasthenia gravis or other neuromuscular disorders.","Risk of hypotension, flushing, and bradycardia with rapid IV administration."]

Clinical Tips & Counseling

Drug interactions

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MAGNESIUM SULFATE IN DEXTROSE 5% IN PLASTIC CONTAINER

Clinical safety rating: caution

Comprehensive clinical and safety monograph for MAGNESIUM SULFATE IN DEXTROSE 5% IN PLASTIC CONTAINER (MAGNESIUM SULFATE IN DEXTROSE 5% IN PLASTIC CONTAINER).

How it works

What the body does with it

Metabolism	Magnesium is not metabolized; it is primarily excreted unchanged by the kidneys via glomerular filtration and tubular reabsorption. Elimination half-life is approximately 4-6 hours in normal renal function.
Excretion	Primarily renal (90-100% as unchanged magnesium). Less than 1% biliary/fecal.
Half-life	Terminal half-life approximately 4-5 hours in normal renal function; prolonged in renal impairment (up to 40 hours).
Protein binding	Approximately 25-30% bound to albumin.
Volume of Distribution	0.2-0.3 L/kg; distributes primarily in extracellular fluid.
Bioavailability	IV: 100%. Not administered orally for systemic effect due to poor GI absorption (<30%).
Onset of Action	IV: immediate (within seconds to minutes).
Duration of Action	IV: 30 minutes (anticonvulsant effect); continuous infusion required for sustained effect.

Classification & Brands

Dosing & administration

Dosage form	INJECTABLE
Renal impairment	GFR 30-50 mL/min: reduce dose by 50% and monitor serum magnesium; GFR <30 mL/min: contraindicated or use extreme caution with dose reduction to 25% of normal and frequent monitoring.
Liver impairment	Child-Pugh A (mild): no specific adjustment; Child-Pugh B (moderate): use with caution, consider dose reduction; Child-Pugh C (severe): avoid use or reduce dose by 50% with close monitoring of magnesium levels and renal function.
Pediatric use	Loading dose: 20-40 mg/kg intravenously over 1-2 hours; maintenance: 10-20 mg/kg IV every 4-6 hours as needed; maximum infusion rate 150 mg/min; monitor serum magnesium during therapy.
Geriatric use	Reduce initial dose by 25-50% due to age-related decline in renal function; monitor serum magnesium and renal function closely; adjust dose based on GFR and clinical response.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for MAGNESIUM SULFATE IN DEXTROSE 5% IN PLASTIC CONTAINER (MAGNESIUM SULFATE IN DEXTROSE 5% IN PLASTIC CONTAINER).

Breastfeeding	Magnesium sulfate is excreted into breast milk in low amounts; M/P ratio approximately 0.2-0.3. Usually compatible with breastfeeding but monitor infant for hypotonia, lethargy, or feeding difficulties if high maternal doses are used long-term.
Teratogenic Risk	Magnesium sulfate crosses the placenta and is not associated with major teratogenic effects when used for standard obstetric indications. Prolonged exposure (e.g., >5-7 days) in the second/third trimester may cause fetal hypocalcemia, skeletal abnormalities, or neonatal hypotonia. Continuous infusion near delivery may lead to neonatal respiratory depression and flaccidity.