Magnesium Sulfate

Class: Anticonvulsants, Miscellaneous
VA Class: CN400
CAS Number: 10034-99-8

Introduction

Anticonvulsant parenterally; electrolyte; required cofactor for numerous human enzyme systems.^{a h}

Uses for Magnesium Sulfate

Prevention and Control of Seizures

Injection mainly used as an anticonvulsant for the prevention and control of seizures in toxemia (preeclampsia or eclampsia) of pregnancy, acute nephritis (in children), and in various other conditions.⁶⁷

Toxemias of Pregnancy

Generally considered the anticonvulsant drug of choice for the prevention and control of seizures in severe preeclampsia or in eclampsia,^{58 59 60 61} and appears to be more effective than phenytoin.^{58 60 61 d}

Opinions differ regarding the role for prophylactic use in preventing seizures in mild preeclampsia or gestational hypertension†.^d

Also used in the management of uterine tetany, especially that associated with the use of oxytocic agents.^a

Acute Nephritis in Children

Has been used to control seizures, encephalopathy, and hypertension associated with acute nephritis in children.⁶⁷ However, other agents (e.g., barbiturates, reserpine, hydralazine) should be tried first.⁶⁷

Some clinicians caution not to use parenteral magnesium sulfate to control seizures unless hypomagnesemia has been confirmed, and to monitor serum magnesium concentration when administered.^a

Reserve IV use for immediate control of life-threatening seizures.^a

Other Seizure Etiologies

Parenterally, may be useful to control seizures associated with epilepsy, glomerulonephritis, or hypothyroidism, since low plasma concentrations of magnesium may be a contributing cause of seizures in these conditions.^a

Prevention and Treatment of Hypomagnesemia

Injection is added to total parenteral nutrition admixtures to correct or prevent hypomagnesemia.⁶⁷

Treatment of acute hypomagnesemia associated with clinical conditions including malabsorption syndromes, alcoholism, cirrhosis of the liver, acute pancreatitis, or prolonged IV therapy with magnesium-free fluids.^{a 70}

Especially effective in the treatment of acute hypomagnesemia accompanied by signs of tetany similar to those of hypocalcemia;⁶⁷ usually, serum magnesium concentrations are below the lower limits of normal (1.5–2.5 or 3 mEq/L), and serum calcium concentrations are either normal (4.3–5.3 mEq/L) or elevated in such cases.⁶⁷

Preterm Labor

Has been used to inhibit uterine contractions in preterm labor (tocolysis)† and prolong gestation when beneficial.^{13 14}

Previously, the American College of Obstetricians and Gynecologists (ACOG) considered magnesium sulfate a first-line tocolytic agent of choice; currently, ACOG states that there is no clear first-line tocolytic agent.⁶⁹

May be contraindicated by maternal or fetal conditions.¹³ (See Contraindications under Cautions.)

Following successful cessation of uterine contractions, oral maintenance therapy with other magnesium salts (e.g., oxide or gluconate) has not been consistently beneficial.^{13 20}

Combination therapy with another tocolytic agent may be more effective than single-agent therapy, but may increase risk of maternal morbidity, and safety and efficacy have not been established; use with caution.^{13 19 24 25 27 69}

Concurrent use of magnesium sulfate and nifedipine may be particularly risky (e.g., development of severe hypotension and neuromuscular blockade).^{13 32 69}

Arrhythmias

Used IV successfully for the treatment of life-threatening arrhythmias such as atypical VT† (torsades de pointes).^{h 8 9 10}

Considered one of several preferred drugs in the treatment of polymorphic VT suspected of being torsades de pointes† in patients in whom initial attempts at correcting or managing potential precipitating factors (e.g., ischemic cardiac events, electrolyte imbalance, drugs known to prolong the QT interval) have not been successful.^{h 64 66 70}

Not recommended in the treatment of cardiac arrest except when the ECG monitoring shows torsades de pointes.⁷⁰

Drug-induced cardiovascular emergencies or altered vital signs: May consider use in VT associated with tricyclic antidepressant toxicity; however, use may aggravate drug-induced hypotension.⁷⁰ Anecdotal evidence suggests that magnesium sulfate also may be an effective treatment in antiarrhythmic drug-induced torsades de pointes even in the absence of magnesium deficiency.^{66 70}

Has been used IV in the management of paroxysmal atrial tachycardia† when other measures have failed and when there is no evidence of myocardial damage.^a

May consider use in atrial fibrillation with a rapid ventricular response† for rate control.⁷⁰

AMI

Has been administered IV adjunctively to reduce cardiovascular morbidity and mortality (e.g., through reduction in ventricular arrhythmias and/or limitation of infarct size and reperfusion injury) associated with AMI†;^{2 6 7 34 35 36 37 38 39 64} however, evidence of benefit is contradictory and the precise role remains unclear.^{34 44 45 46 47 64}

Routine magnesium prophylaxis in AMI no longer recommended.^{64 70}

Instead, ACC and AHA currently recommend that magnesium in AMI be reserved for patients with documented magnesium and/or potassium deficits, especially in patients receiving diuretics prior to infarction.⁶⁴

ACC/AHA state that it is sound clinical practice to maintain magnesium concentrations >2 mEq/L in patients with AMI.^{64 66 70}

Recommended by ACC/AHA in AMI for episodes of torsades de pointes-type VT.^{64 66}

Recommended by ACC/AHA for consideration in high-risk patients such as geriatric patients and/or those for whom reperfusion therapy is not suitable.

ACC/AHA state that mortality reduction may be possible with magnesium use in certain high-risk patients with AMI (e.g., geriatric patients, those who are not eligible for reperfusion therapy) if they receive the drug as soon as possible after symptom onset (within 6 hours); however, conflicting evidence and/or divergence of opinion about usefulness/efficacy.^{64 66}

Acute Asthma

May modestly improve pulmonary function and reduce hospital admissions when combined with nebulized β-adrenergic agents and corticosteroids, particularly in patients with severe exacerbations of asthma†.⁷⁰

Barium Poisoning

Administered IV to counteract the intense muscle stimulating effects of barium poisoning.

Also may administer by gastric lavage or oral solution to precipitate and remove unabsorbed barium.^a (See Dosage under Dosage and Administration.)

Magnesium Sulfate Dosage and Administration

Administration

Administer IV or IM.^{a 70}

For ACLS during CPR, may be administered by intraosseous infusion† when IV injection is not possible.⁷⁰

IV Administration

Generally, concentration should not be >200 mg/mL (20%).^a

Rate of Administration

Risk of vasodilation or hypotension if administered rapidly.⁷⁰

Usually, do not exceed 150 mg/minute (e.g., 1.5 mL/minute of a 10% concentration or equivalent) except in patients with seizures associated with severe eclampsia (e.g., up to 1.33 g/minute for loading dose), preterm labor (e.g., 300 mg/minute for loading dose), or arrhythmias (e.g., 1–6 g over several minutes; 3–4 g over 30 seconds with extreme caution).⁶⁷

IM Administration

Generally, use concentrations of 250 mg/mL (25%) or 500 mg/mL (50%).^a

Infants and children: Usually, use concentration ≤200 mg/mL (20%).^a However, higher concentrations (e.g., 50%) have been used.^{a c}

Intraosseous Administration

When IV administration is not possible, magnesium sulfate may be given by intraosseous infusion† for CPR.⁷⁰

Dosage

Adjust dosage carefully according to individual requirements and response; discontinue as soon as the desired effect is obtained.^a

Pediatric Patients

PALS in CPR

Torsades de Pointes† or Suspected Hypomagnesemia

IV or Intraosseous

Infuse 25–50 mg/kg (up to 2 g) over 10–20 minutes.⁷⁰

Infuse more rapidly (over several minutes) in torsades de pointes†.⁷⁰

Prevention and Control of Seizures

Acute Nephritis in Children

IM

To control seizures, encephalopathy, and hypertension: 100 mg/kg (0.8 mEq/kg or 0.2 mL/kg of a 50% solution) every 4–6 hours as needed.^a

Alternatively to control seizures: 20–40 mg/kg (0.16–0.32 mEq/kg or 0.1–0.2 mL/kg of a 20% solution) as needed.⁶⁷

IV

If symptoms are severe, may administer a 1–3% solution in a dosage of 100–200 mg/kg.^a

Administer slowly; closely monitor BP.^a

Administer total dose within 1 hour, with ½ the dose administered in the first 15–20 minutes.^a

Hypomagnesemia

Prevention

Additive in Total Parenteral Infusion

Infants: Usually, 0.25–0.6 mEq/kg daily.⁶⁷

Maintenance requirements not precisely known.⁶⁷

Treatment

IM

Older children: For deficiency that is not severe, manufacturers recommend 1 g (2 mL of 50% solution) once or twice daily; use serum magnesium values as guide to continued dosage.^c

Adults

Prevention and Control of Seizures

Toxemias of Pregnancy

For the management of preeclampsia or eclampsia, dilute (1–8%) solutions are often given by IV infusion in combination with IM injections using 50% magnesium sulfate.⁶⁸

IV with IM

Severe preeclampsia or eclampsia: Initially, IV infusion of 4–5 g (32.4–40.5 mEq) diluted in 250 mL of 5% dextrose injection or 0.9% sodium chloride injection, in combination with IM injection of up to 10 g (10 mL of undiluted 50% solution administered into each buttock).⁶⁷ Alternatively, after the initial 4- to 5-g IV dose, constant IV infusion of 1–3 g/hour has been recommended.^a Total initial dose: 10–14 g (81–113.4 mEq).^{67 68}

Alternatively, 8–15 g IV initially, depending on weight (8 g for a 45-kg patient to 15 g for a 90-kg patient); 4 g (undiluted or diluted in 5% dextrose injection); give remainder of initial dose IM using undiluted 50% injection.^a Base dosage for the next 24 hours on the serum magnesium concentration and urinary excretion after the initial dose.^a Subsequent doses should be sufficient to replace the magnesium excreted in the urine and will be approximately 65% of the initial dose administered IM at 6-hour intervals.^a

Alternatively, the manufacturer recommends that an initial dose of 4 g (32.4 mEq) be given IV by diluting the 50% solution to 10 or 20% concentration; may then inject 40 mL of a 10% solution or 20 mL of a 20% solution IV over 3–4 minutes.⁶⁷ Administer subsequent 4- to 5-g doses (32.4–40.5 mEq or 8–10 mL of the undiluted 50% injection) IM into alternate buttocks every 4 hours as needed, depending on the continuing presence of the patellar reflex and adequate respiratory function.⁶⁷

Continue therapy until paroxysms cease.⁶⁷

Serum magnesium concentration of 6 mg/dL is considered optimal for seizure control.⁶⁷

IV

For eclampsia, ACOG currently recommends 4–6 g in 100 mL of IV fluid over 15–20 minutes, followed by 2 g per hour continuous IV infusion; use antihypertensive agents for women with DBP ≥105–110 mm Hg.^d

Other Seizure Etiologies

IM or IV

For seizures associated with epilepsy, glomerulonephritis, or hypothyroidism: Usually, 1 g.^a

Hypomagnesemia

Prevention

IV Infusion

Additive in total parenteral nutrition: Usually, 5–8 mEq daily.⁶⁷

Maintenance requirements are not precisely known.⁶⁷

Treatment

Use caution to prevent exceeding the renal excretory capacity.^a

IM

Mild deficiency: Usually, 1 g (8.12 mEq or 2 mL of the 50% solution) every 6 hours for 4 doses.⁶⁷

Alternatively, for deficiency that is not severe, 1 g (2 mL of 50% solution) once or twice daily; use serum magnesium concentrations as guide to continued dosage.^c

Severe deficiency: If necessary, may administer up to 250 mg (about 2 mEq or 0.5 mL of the 50% solution) per kg of body weight within a 4-hour period.^{a f}

Alternatively, for severe hypomagnesemia: 1–5 g (2–10 mL of 50% solution) daily in divided doses; repeat daily until serum levels are normal.^c

Oral

For mild deficiency: 3 g every 6 hours for 4 doses.^a

IV infusion

For severe deficiency: 5 g (approximately 40 mEq) added to 1 L of 5% dextrose injection or 0.9% sodium chloride injection over 3 hours.^{67 f}

Alternatively, for severe or symptomatic hypomagnesemia, 1–2 g over 5–60 minutes.⁷⁰ If seizures are present, administer 2 g over 10 minutes.⁷⁰

Preterm Labor†

Carefully adjust rate and duration of infusion according to the patient’s response as indicated (by uterine response, maternal and fetal tolerance).^{13 14 15 16 17 18}

Monitoring of serum magnesium concentrations may be useful to minimize the risk of toxicity (e.g., respiratory depression, cardiotoxicity, maternal tetany, muscular paralysis, hypotension) and to determine the maximum safe infusion rate.^{13 33}

Monitor amount and rate of IV fluid administration to avoid circulatory overload.¹³

Observe for signs and symptoms of pulmonary edema.¹³

IV Infusion

Acute tocolytic therapy: Loading dose of 4–6 g over 20 minutes; after contractions cease, follow with maintenance infusions of 2–4 g/hour for 12–24 hours as tolerated.^{13 14 15 16 17 18 e}

Arrhythmias

Atypical VT (Torsades de Pointes)†

IV

1–6 g over several minutes, occasionally followed by approximately 3–20 mg/minute by IV infusion for 5–48 hours, depending on response and serum magnesium concentrations.^{8 9 10 64}

Alternatively, for torsades de pointes associated with cardiac (pulseless) arrest†, 1–2 g in 10 mL 5% dextrose injection over 5–20 minutes.⁷⁰

Alternatively, for torsades de pointes in a patient with pulses†, give a loading dose of 1–2 g (8–16 mEq) in 50–100 mL 5% dextrose injection over 5–60 minutes.⁷⁰

Intraosseous

Torsades de pointes associated with cardiac (pulseless) arrest†: 1–2 g in 10 mL 5% dextrose injection over 5–20 minutes.⁷⁰

Paroxysmal Atrial Tachycardia†

IV

Usually, 3–4 g (e.g., 30–40 mL of a 10% solution) over 30 seconds with extreme caution.

AMI†

IV

Optimum dosage not established.

2-g over 5–15 minutes, followed by 18 g over 24 hours (approximately 12.5 mg/minute).⁶⁴

Timing appears to be an important prognostic factor;^{34 56 57 64} initiate administration as soon as possible (preferably no later than 6 hours) after symptom onset.⁶⁴

Acute Asthma†

IV

Usually, 1.2–2 g over 20 minutes.⁷⁰

Barium Poisoning

IV

Usually, 1–2 g to counteract the intense muscle stimulating effects of barium.^a

Gastric Lavage or Oral

May administer 2–5% magnesium sulfate (or sodium sulfate) solution by gastric lavage to precipitate and remove unabsorbed barium remaining in the GI tract.^a

Alternatively, may administer 5–10% magnesium sulfate (or sodium sulfate) solution (up to 60 g) orally to precipitate barium and produce catharsis.^a

Prescribing Limits

Pediatric Patients

PALS in CPR

Torsades de Pointes† or Suspected Hypomagnesemia

IV or Intraosseous

Maximum 2 g, as a single dose.⁷⁰

Adults

Prevention and Control of Seizures

Toxemias of Pregnancy

IV with IM

Do not exceed total daily dosage of 30–40 g.^a

Special Populations

Renal Impairment

Prevention and Control of Seizures

Toxemias of Pregnancy

IV with IM

Maximum 20 g/48 hours in severe renal impairment.^a

Geriatric Patients

Often require reduced dosage because of impaired renal function.^f Maximum 20 g/48 hours in severe renal impairment.^f

Cautions for Magnesium Sulfate

Contraindications

• 
  

  Parenteral administration in heart block or myocardial damage.^{a c}

  
  


• 
  

  Tocolytic therapy in general may be contraindicated by some maternal or fetal conditions (e.g., acute fetal distress other than intrauterine resuscitation, chorioamnionitis, fetal demise [singleton], fetal maturity, maternal hemodynamic instability).¹³

  
  


• 
  

  Tocolytic therapy may be contraindicated by hypocalcemia, myasthenia gravis, renal failure.¹³

  
  


• 
  

  In toxemia of pregnancy during 2 hours prior to delivery.^{67 68}

  
  

Warnings/Precautions

Warnings

Toxicity

Principal hazard is hypermagnesemia, most immediate life-threatening effect is respiratory depression; have IV calcium (e.g., calcium gluconate) readily available for use as antidote.^{a c 70}

Adverse effects of parenteral therapy are caused by magnesium intoxication.^a

Toxic manifestations (may begin at serum magnesium concentrations of 4 mEq/L) include neurologic symptoms (e.g., muscular weakness, flaccid paralysis, ataxia, drowsiness, confusion, depression of reflexes), flushing, sweating, vasodilation, hypotension, hypothermia, depression of cardiac function, bradycardia, cardiac arrhythmias, circulatory collapse, hypoventilation, and CNS depression (depressed level of consciousness); can proceed to fatal respiratory paralysis.^{a 70}

Observe carefully, and monitor serum magnesium concentrations to avoid overdosage and toxicity.^a

During tocolytic therapy, observe carefully and monitor serum magnesium concentrations to minimize the risk of toxicity (e.g., respiratory depression, cardiotoxicity, maternal tetany, muscular paralysis, hypotension).^{13 21 22 23}

Hypocalcemia with signs of tetany can occur during tocolytic use.^a

Patellar reflex disappearance is useful to detect intoxication onset.^a Test knee jerk reflexes before each dose; if absent, give no additional magnesium until they return.^a

Make sure respiration rate is ≥16/minute prior to each dose.^a

Do not continue dosage unless urine output is 100 mL or more during the 4 hours preceding each dose.^a

If overdosage occurs, provide artificial ventilation until a calcium salt can be given IV.^a

In adults, IV administration of 5–10 mEq of calcium (e.g., 10–20 mL of 10% calcium gluconate) usually will reverse respiratory depression or heart block caused by magnesium intoxication.^a

Peritoneal dialysis or hemodialysis may be required in extreme cases of hypermagnesemia.^a

Maternal Pulmonary Edema

Risk of maternal pulmonary edema with tocolytic therapy; development during the initial 24 hours is uncommon.¹³

Etiology is unclear;¹³ risk factors include excessive hydration, multiple gestation, occult sepsis, and underlying cardiac disease.¹³

Adjunctive corticosteroid therapy apparently is not an important risk factor .¹³

Reduce risk by limiting fluid intake to 2.5–3 L daily, limiting sodium intake, and maintaining maternal pulse <130 bpm.¹³

Monitor amount and rate of IV fluid administration to avoid circulatory overload; observe carefully for signs/symptoms of pulmonary edema.¹³

Hypocalcemia

Clinically important hypocalcemia with signs of tetany has occurred after use for eclampsia.^a Changes in calcium and phosphorus balance should be anticipated in each case of parenteral magnesium administration.^a

Major Toxicities

Respiratory Depression

See Warnings under Cautions.

General Precautions

Use with caution if flushing and sweating occur.^c

CNS Depressants

Adjust dosage carefully with concomitant use; have IV calcium (e.g., calcium gluconate) readily available for use as antidote for magnesium toxicity.^{a c} (See CNS Depressants under Interactions.)

Laboratory Tests

Confirm hypomagnesemia, monitor serum magnesium concentration.^c (See Warnings under Cautions.)

Specific Populations

Pregnancy

Category A or B.^{67 68 f}

Although one manufacturer states category D and that parenteral magnesium may cause fetal harm in pregnant women or those becoming pregnant during use,^c most experts consider the drug category B and state that maternal anticonvulsant or tocolytic use usually does not pose fetal or neonatal risk except with prolonged IV infusions.^b

Increased possibility of neonatal toxicity (including neuromuscular or respiratory depression) with prolonged continuous IV infusion before delivery (especially for >24 hours); IM use does not usually compromise neonate.^{a b}

Do not give IV during the 2 hours preceding delivery.^a

Neonatal hypermagnesemia management may require resuscitation and assisted ventilation via endotracheal intubation and/or intermittent positive-pressure ventilation, as well as IV calcium.^a

Lactation

Distributed into milk.^{a b} Caution if used in nursing women,^a but generally considered compatible with breast-feeding.^b

Milk magnesium concentrations increased for only about 24 hours after discontinuance of parenteral magnesium; amount ingested by a nursing infant during this period is probably too small to be of clinical importance.^{a b}

Pediatric Use

Although one manufacturer states safety and efficacy not established in children,^c other manufacturers make no pediatric restrictions.^{67 68 f g}

Included in current CPR guidelines for pediatric advanced life support (PALS).^{70 64}

Geriatric Use

Often requires reduced dosage because of impaired renal function.^f (See Geriatric Use under Dosage and Administration.)

Renal Impairment

Administer with caution in renal impairment; danger of magnesium intoxication.^{a c f}

Reduce dosage and obtain frequent serum magnesium concentrations in severe renal impairment.^a (See Renal Impairment under Dosage and Administration.)^a

Common Adverse Effects

Flushing, sweating, hypotension, depression of reflexes, flaccid paralysis, hypothermia, circulatory collapse, depression of cardiac function, CNS depression.^a

Interactions for Magnesium Sulfate

Specific Drugs

Drug	Interaction	Comments
CNS depressants (e.g., barbiturates, opiates, general anesthetics)	Additive central depressant effects with concomitant usea	Adjust dosage carefullya Have IV calcium (e.g., calcium gluconate) preparation readily available for use as antidotec
Digoxin	Serious changes in cardiac conduction; may cause heart block if IV calcium is required to treat magnesium toxicitya	Use with extreme caution in digitalized patientsa
Neuromuscular blocking agents	Excessive neuromuscular blockade a	Use concomitantly with cautiona

Magnesium Sulfate Pharmacokinetics

Absorption

Onset

IV administration: Immediate onset.^a

IM administration: About 1 hour.^a

Duration

IV administration: About 30 minutes.^a

IM administration: 3–4 hours.^a

Plasma Concentrations

Effective anticonvulsant serum magnesium concentrations: 2.5–7.5 mEq/L.^a

Monitor for hypermagnesemia (serum concentrations >2.5 mEq/L); toxic effects (e.g., depression of deep-tendon reflexes) may begin at 4 mEq/L.^a

At 10 mEq/L, deep-tendon reflexes disappear and respiratory paralysis may occur; complete heart block can occur at about 10 mEq/L.^a

Serum magnesium >12 mEq/L may be fatal.

Distribution

Extent

Crosses the placenta.^{a b}

Distributes into milk.^{a b}

Elimination

Elimination Route

Excreted by the kidneys; interindividual variability in rate but directly proportional to serum concentration and glomerular filtration.^{a h}

Stability

Storage

Parenteral

Injection

15–30°C.^{67 f g}

Magnesium Sulfate in 5% Dextrose Injection

25°C (may expose to up to 40°C).⁶⁷ Avoid freezing.^a

Compatibility

For information on systemic interactions resulting from concomitant use, see Interactions.

Incompatible with alkali hydroxides (forming insoluble magnesium hydroxide), with alkali carbonates (forming basic carbonates), and with salicylates (forming basic salicylates).^a

Reacts with arsenates, phosphates, and tartrates, precipitating the corresponding magnesium salts.^a

Lead, barium, strontium, and calcium react with magnesium sulfate resulting in precipitation of the respective sulfates.^a

Parenteral

Solution Compatibility^HID

Compatible
Dextrose 5% in water
Ringer’s injection, lactated
Sodium chloride 0.9%
Incompatible
Fat emulsion 10%, IV

Drug Compatibility

Admixture CompatibilityHID

Compatible
Chloramphenicol sodium succinate
Cisplatin
Heparin sodium
Hydrocortisone sodium succinate
Isoproterenol HCl
Linezolid
Meropenem
Methyldopate HCl
Norepinephrine bitartrate
Penicillin G potassium
Potassium chloride
Potassium phosphates
Verapamil HCl
Incompatible
Amphotericin B
Cyclosporine
Dobutamine HCl
Polymyxin B sulfate
Procaine HCl
Sodium bicarbonate
Variable
Calcium chloride
Calcium gluconate

Y-Site CompatibilityHID

Compatible
Acyclovir sodium
Aldesleukin
Amifostine
Amikacin sulfate
Ampicillin sodium
Aztreonam
Bivalirudin
Cefazolin sodium
Cefotaxime sodium
Cefoxitin sodium
Chloramphenicol sodium succinate
Clindamycin phosphate
Co-trimoxazole
Dexmedetomidine HCl
Dobutamine HCl
Docetaxel
Doxorubicin HCl liposome injection
Doxycycline hyclate
Enalaprilat
Erythromycin lactobionate
Esmolol HCl
Etoposide phosphate
Famotidine
Fenoldopam mesylate
Fludarabine phosphate
Gallium nitrate
Gentamicin sulfate
Granisetron HCl
Heparin sodium
Hetastarch in lactated electrolyte injection (Hextend)
Hydrocortisone sodium succinate
Hydromorphone HCl
Idarubicin HCl
Kanamycin sulfate
Labetalol HCl
Linezolid
Meperidine HCl
Metronidazole
Milrinone lactate
Morphine sulfate
Nafcillin sodium
Nicardipine HCl
Ondansetron HCl
Oxacillin sodium
Oxaliplatin
Paclitaxel
Penicillin G potassium
Piperacillin sodium–tazobactam sodium
Potassium chloride
Propofol
Remifentanil HCl
Sargramostim
Sodium nitroprusside
Thiotepa
Tobramycin sulfate
Vancomycin HCl
Vitamin B complex with C
Incompatible
Amphotericin B cholesteryl sulfate complex
Cefepime HCl
Drotrecogin alfa (activated)
Lansoprazole
Variable
Amiodarone
Ciprofloxacin

ActionsActions

• 
  

  Hypermagnesemia (serum magnesium concentrations >2.5 mEq/L) may depress the CNS and block peripheral neuromuscular transmission, producing anticonvulsant effects.^a

  
  


• 
  

  Exact mechanism is not fully known; excess magnesium appears to decrease the amount of acetylcholine liberated by the motor nerve impulse.^a

  
  


• 
  

  Magnesium ions slow the rate of the SA node impulse formation and prolong conduction time in animals.^a

  
  


• 
  

  IV infusion prolongs PR interval, H (atria-His bundle) interval, antegrade AV nodal effective refractory period, and SA conduction time in humans.^a

  
  


• 
  

  Required cofactor for >300 enzyme systems.^h

  
  


• 
  

  Required for both anaerobic and aerobic energy generation and for glycolysis.^h

  
  


• 
  

  Described as nature’s physiologic calcium-channel blocking agent.^h

  
  


• 
  

  During magnesium depletion, intracellular calcium increases, which can cause muscle cramps, hypertension, and coronary and cerebral vasospasms.^h

  
  


• 
  

  Plays an important role in BP regulation; hypertension may be associated with magnesium deficiency and magnesium may decrease BP in hypertension.^h

  
  


• 
  

  Important role in bone and mineral homeostasis and can directly affect bone cell formation and influence hydroxyapatite crystal formation and growth; deficiency may be risk factor for osteoporosis.^h

  
  


• 
  

  Insulin resistance and impaired insulin secretion with deficiency.^h

  
  

Advice to Patients

• 
  

  Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs as well as any concomitant illnesses.^a

  
  


• 
  

  Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.^a

  
  


• 
  

  Importance of informing patients of other important precautionary information. (See Cautions.)

  
  

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Magnesium Sulfate

Routes	Dosage Forms	Strengths	Brand Names	Manufacturer
Bulk	Crystals
Parenteral	Injection	50%*	Magnesium Sulfate Injection	Abraxis, American Regent, Hospira, IMS
	Injection, for IV use only	4% (4, 20, and 40 g)	Magnesium Sulfate Injection	Hospira
		8% (4 g)	Magnesium Sulfate Injection	Hospira

Magnesium Sulfate in Dextrose

Routes	Dosage Forms	Strengths	Brand Names	Manufacturer
Parenteral	Injection, for IV use only	1% (1 g) in 5% Dextrose	Magnesium Sulfate in 5% Dextrose Injection	Hospira

Disclaimer

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. and Drugs.com represent that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. and Drugs.com make no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. and Drugs.com do not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS Drug Information. © Copyright, 1959-2011, Selected Revisions January 2010. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.

† Use is not currently included in the labeling approved by the US Food and Drug Administration.

References

2. Abraham AS, Rosenmann D, Kramer M et al. Magnesium in the prevention of lethal arrhythmias in acute myocardial infarction. Arch Intern Med. 1987; 147:753-5. [IDIS 227956] [PubMed 3548627]

6. Rasmussen HS, Norregard P, McNair P et al. Intravenous magnesium in acute myocardial infarction. Lancet. 1986; 1:234-6. [IDIS 210464] [PubMed 2868254]

7. Rasmussen HS, Grnbaek M, Cintin C et al. One-year death rate in 270 patients with suspected acute myocardial infarction, initially treated with intravenous magnesium or placebo. Clin Cardiol. 1988; 11:377-81. [PubMed 3396238]

8. Allen BJ, Brodsky MA, Capparelli EV et al. Magnesium sulfate therapy for sustained monomorphic ventricular tachycardia. Am J Cardiol. 1989; 64:1202-4. [IDIS 305714] [PubMed 2816773]

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