Dosage Forms
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Solution, Injection, as hexahydrate:
Chloromag: 200 mg/mL (50 mL [DSC]) [contains benzyl alcohol]
Generic: 200 mg/mL (50 mL)
Tablet, Oral:
Generic: Elemental magnesium 64 mg (plus calcium 112 mg)
Tablet Delayed Release, Oral:
Mag-SR Plus Calcium: 535 mg (elemental magnesium 64 mg, plus calcium 106 mg) [starch free, sugar free]
Magdelay: Elemental magnesium 70 mg (plus calcium 118 mg) [DSC]
Nu-Mag: Elemental magnesium 71.5 mg (plus calcium 119 mg) [contains fd&c blue #2 aluminum lake]
Slow Magnesium/Calcium: 535 mg (elemental magnesium 64 mg, plus calcium 106 mg)
Slow-Mag: Elemental magnesium 71.5 mg (plus calcium 119 mg) [contains fd&c blue #2 aluminum lake]
Pharmacology
Mechanism of Action
Magnesium is important as a cofactor in many enzymatic reactions in the body involving protein synthesis and carbohydrate metabolism (at least 300 enzymatic reactions require magnesium). Actions on lipoprotein lipase have been found to be important in reducing serum cholesterol and on sodium/potassium ATPase in promoting polarization (eg, neuromuscular functioning).
Pharmacokinetics/Pharmacodynamics
Absorption
Oral: Inversely proportional to amount ingested; 40% to 60% under controlled dietary conditions; 15% to 36% at higher doses
Distribution
Bone (50% to 60%); extracellular fluid (1% to 2%)
Excretion
Urine (as magnesium)
Protein Binding
30%, to albumin
Use: Labeled Indications
Correction or prevention of hypomagnesemia; dietary supplement
Contraindications
Hypersensitivity to any component of the formulation; renal impairment; myocardial disease; coma
Dosage and Administration
Dosing: Adult
Note: Serum magnesium is poor reflection of repletional status as the majority of magnesium is intracellular; serum levels may be transiently normal for a few hours after a dose is given; therefore, aim for consistently high normal serum levels in patients with normal renal function for most efficient repletion.
Hypomagnesemia, prevention (parenteral nutrition supplementation) (ASPEN [Mirtallo 2004]): IV (elemental magnesium): 8 to 20 mEq/day
Dietary supplement: Oral (Mag 64, Mag-Delay, Slow-Mag): 2 tablets once daily
Dosing: Geriatric
Refer to adult dosing.
Dosing: Pediatric
Note: Dosing presented in mg and mEq, verify dosing units; 1,000 mg of magnesium chloride = 119.7 mg elemental magnesium = 9.85 mEq elemental magnesium = 4.93 mmol elemental magnesium; serum magnesium is poor reflection of repletional status as the majority of magnesium is intracellular; serum concentrations may be transiently normal for a few hours after a dose is given; therefore, aim for consistently high normal serum concentrations in patients with normal renal function for most efficient repletion.
Hypomagnesemia: Limited data available:
Infants, Children, and Adolescents: Dose expressed as elemental magnesium:
IV: 2.5 to 5 mg/kg/dose every 6 hours for 2 to 3 doses; dosing based on experience with magnesium sulfate salt which is preferred (Kliegman 2011).
Oral: Note: Achieving optimal magnesium levels using oral therapy may be difficult due to the propensity for magnesium to cause diarrhea; IV replacement may be more appropriate particularly in situations of severe deficit: 10 to 20 mg/kg/dose up to 4 times daily (Kliegman 2007).
Parenteral nutrition, maintenance magnesium requirement (ASPEN [Mirtallo 2004]): Note: Dose expressed as elemental magnesium:
Infants and Children ≤50 kg: IV: 0.3 to 0.5 mEq/kg/day as an additive to parenteral nutrition solution.
Children >50 kg and Adolescents: IV: 10 to 30 mEq/day as an additive to parenteral nutrition solution.
Reconstitution
Dilute magnesium chloride 4 g in 250 mL D5W.
Dietary Considerations
Whole grains, legumes, and dark-green leafy vegetables are dietary sources of magnesium.
Adequate intake (AI) (elemental magnesium) (IOM 1997):
1 to 6 months: 30 mg daily
7 to 12 months: 75 mg daily
Dietary recommended daily allowance (RDA) (elemental magnesium) (IOM 1997):
1 to 3 years: 80 mg/day
4 to 8 years: 130 mg/day
9 to 13 years: 240 mg/day
14 to 18 years:
Females: 360 mg/day
Pregnancy: 400 mg/day
Lactation: 360 mg/day
Males: 410 mg/day
19 to 30 years:
Females: 310 mg/day
Pregnancy: 350 mg/day
Lactation: 310 mg/day
Males: 400 mg/day
≥31 years:
Females: 320 mg/day
Pregnancy: 360 mg/day
Lactation: 320 mg/day
Males: 420 mg/day
Storage
Injection: Prior to reconstitution, store at controlled room temperature of 15°C to 30°C (59°F to 86°F).
Magnesium Chloride Images
Drug Interactions
Alfacalcidol: May increase the serum concentration of Magnesium Salts. Consider therapy modification
Alpha-Lipoic Acid: Magnesium Salts may decrease the absorption of Alpha-Lipoic Acid. Alpha-Lipoic Acid may decrease the absorption of Magnesium Salts. Consider therapy modification
Baloxavir Marboxil: Polyvalent Cation Containing Products may decrease the serum concentration of Baloxavir Marboxil. Avoid combination
Bictegravir: Polyvalent Cation Containing Products may decrease the serum concentration of Bictegravir. Management: Administer bictegravir under fasting conditions at least 2 hours before or 6 hours after polyvalent cation containing products. Coadministration of bictegravir with or 2 hours after most polyvalent cation products is not recommended. Consider therapy modification
Bisphosphonate Derivatives: Polyvalent Cation Containing Products may decrease the serum concentration of Bisphosphonate Derivatives. Management: Avoid administration of oral medications containing polyvalent cations within: 2 hours before or after tiludronate/clodronate/etidronate; 60 minutes after oral ibandronate; or 30 minutes after alendronate/risedronate. Exceptions: Pamidronate; Zoledronic Acid. Consider therapy modification
Calcitriol (Systemic): May increase the serum concentration of Magnesium Salts. Management: Consider using a non-magnesium-containing antacid or phosphate-binding product in patients also receiving calcitriol. If magnesium-containing products must be used with calcitriol, serum magnesium concentrations should be monitored closely. Consider therapy modification
Calcium Channel Blockers: May enhance the adverse/toxic effect of Magnesium Salts. Magnesium Salts may enhance the hypotensive effect of Calcium Channel Blockers. Monitor therapy
Deferiprone: Polyvalent Cation Containing Products may decrease the serum concentration of Deferiprone. Management: Separate administration of deferiprone and oral medications or supplements that contain polyvalent cations by at least 4 hours. Consider therapy modification
Dolutegravir: Magnesium Salts may decrease the serum concentration of Dolutegravir. Management: Administer dolutegravir at least 2 hours before or 6 hours after oral magnesium salts. Administer the dolutegravir/rilpivirine combination product at least 4 hours before or 6 hours after oral magnesium salts. Consider therapy modification
Doxercalciferol: May enhance the hypermagnesemic effect of Magnesium Salts. Management: Consider using a non-magnesium-containing antacid or phosphate-binding product in patients also receiving doxercalciferol. If magnesium-containing products must be used with doxercalciferol, serum magnesium concentrations should be monitored closely. Consider therapy modification
Eltrombopag: Polyvalent Cation Containing Products may decrease the serum concentration of Eltrombopag. Management: Administer eltrombopag at least 2 hours before or 4 hours after oral administration of any polyvalent cation containing product. Consider therapy modification
Gabapentin: Magnesium Salts may enhance the CNS depressant effect of Gabapentin. Specifically, high dose intravenous/epidural magnesium sulfate may enhance the CNS depressant effects of gabapentin. Magnesium Salts may decrease the serum concentration of Gabapentin. Management: Administer gabapentin at least 2 hours after use of a magnesium-containing antacid. Monitor patients closely for evidence of reduced response to gabapentin therapy. Monitor for CNS depression if high dose IV/epidural magnesium sulfate is used. Consider therapy modification
Levothyroxine: Magnesium Salts may decrease the serum concentration of Levothyroxine. Management: Separate administration of oral levothyroxine and oral magnesium salts by at least 4 hours. Consider therapy modification
Multivitamins/Fluoride (with ADE): Magnesium Salts may decrease the serum concentration of Multivitamins/Fluoride (with ADE). Specifically, magnesium salts may decrease fluoride absorption. Management: To avoid this potential interaction separate the administration of magnesium salts from administration of a fluoride-containing product by at least 1 hour. Consider therapy modification
Mycophenolate: Magnesium Salts may decrease the serum concentration of Mycophenolate. Management: Separate doses of mycophenolate and oral magnesium salts. Monitor for reduced effects of mycophenolate if taken concomitant with oral magnesium salts. Consider therapy modification
Neuromuscular-Blocking Agents: Magnesium Salts may enhance the neuromuscular-blocking effect of Neuromuscular-Blocking Agents. Monitor therapy
PenicillAMINE: Polyvalent Cation Containing Products may decrease the serum concentration of PenicillAMINE. Management: Separate the administration of penicillamine and oral polyvalent cation containing products by at least 1 hour. Consider therapy modification
Phosphate Supplements: Magnesium Salts may decrease the serum concentration of Phosphate Supplements. Management: Administer oral phosphate supplements as far apart from the administration of an oral magnesium salt as possible to minimize the significance of this interaction. Exceptions: Sodium Glycerophosphate Pentahydrate. Consider therapy modification
Quinolones: Magnesium Salts may decrease the serum concentration of Quinolones. Management: Administer oral quinolones several hours before (4 h for moxi/pe/spar-, 2 h for others) or after (8 h for moxi-, 6 h for cipro/dela-, 4 h for lome/pe-, 3 h for gemi-, and 2 h for levo-, nor-, or ofloxacin or nalidixic acid) oral magnesium salts. Exceptions: LevoFLOXacin (Oral Inhalation). Consider therapy modification
Raltegravir: Magnesium Salts may decrease the serum concentration of Raltegravir. Management: Avoid the use of oral / enteral magnesium salts with raltegravir. No dose separation schedule has been established that adequately reduces the magnitude of interaction. Avoid combination
Tetracyclines: Magnesium Salts may decrease the absorption of Tetracyclines. Only applicable to oral preparations of each agent. Exceptions: Eravacycline. Consider therapy modification
Trientine: Polyvalent Cation Containing Products may decrease the serum concentration of Trientine. Management: Avoid concomitant administration of trientine and oral products that contain polyvalent cations. If oral iron supplements are required, separate the administration by 2 hours. If other oral polyvalent cations are needed, separate administration by 1 hour. Consider therapy modification
Adverse Reactions
Frequency not defined: Gastrointestinal: Diarrhea (excessive oral doses)
Warnings/Precautions
Disease-related concerns:
- Neuromuscular disease: Use with extreme caution in patients with myasthenia gravis or other neuromuscular disease.
- Renal impairment: Use with caution in patients with renal impairment; accumulation of magnesium may lead to magnesium intoxication.
Special populations:
- Obstetrics: Vigilant monitoring and safe administration techniques (ISMP Medication Safety Alert, 2005) recommended to avoid potential for errors resulting in toxicity. Monitor patient and fetal status, and serum magnesium levels closely.
Dosage form specific issues:
- Aluminum: The parenteral product may contain aluminum; toxic aluminum concentrations may be seen with high doses, prolonged use, or renal dysfunction. Premature neonates are at higher risk due to immature renal function and aluminum intake from other parenteral sources. Parenteral aluminum exposure of >4 to 5 mcg/kg/day is associated with CNS and bone toxicity; tissue loading may occur at lower doses (Federal Register, 2002). See manufacturer’s labeling.
- Benzyl alcohol and derivatives: Some dosage forms may contain benzyl alcohol; large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity (“gasping syndrome”) in neonates; the “gasping syndrome” consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension, and cardiovascular collapse (AAP ["Inactive" 1997]; CDC, 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors, 2001); avoid or use dosage forms containing benzyl alcohol with caution in neonates. See manufacturer’s labeling.
Other warnings/precautions:
- Electrolyte abnormalities: Concurrent hypokalemia or hypocalcemia can accompany a magnesium deficit. Hypomagnesemia is associated with hypokalemia and requires correction in order to normalize potassium.
- Parenteral administration: Monitor serum magnesium level, respiratory rate, blood pressure, deep tendon reflex, and renal function when administered parenterally, particularly with repeated dosing; magnesium toxicity can lead to fatal cardiovascular arrest and/or respiratory paralysis.
Monitoring Parameters
IV: Rapid administration: ECG monitoring, vital signs, deep tendon reflexes; magnesium, calcium, and potassium levels; renal function during administration
Oral: Renal function; magnesium levels; bowel movements
Pregnancy
Pregnancy Risk Factor
C
Pregnancy Considerations
Animal reproduction studies have not been conducted. Magnesium crosses the placenta; serum levels in the fetus correlate with those in the mother (Idama, 1998; Osada, 2002).
Patient Education
What is this drug used for?
- It is used to treat or prevent low magnesium levels.
Other side effects of this drug: Talk with your doctor right away if you have any of these signs of:
- Flushing
- Sweating a lot
- Dizziness
- Passing out
- Loss of strength and energy
- Shortness of breath
- Sensation of cold
- Severe nausea
- Severe vomiting
- Severe diarrhea
- Signs of a significant reaction like wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat.
Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.
Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.
