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Magnesium Sulfate


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


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

Used to correct or prevent hypomagnesemia in patients receiving total parenteral nutrition.67

Also used 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 and Fetal Neuroprotection

Has been used to inhibit uterine contractions in preterm labor (tocolysis) and prolong gestation when considered beneficial.14 69 However, efficacy and safety not established; not labeled by FDA for this use.69 75 76

ACOG states that β-adrenergic agonists, calcium-channel blocking agents, and NSAIAs are first-line tocolytic agents.69

Has been used for fetal neuroprotection prior to preterm delivery to reduce the risk of cerebral palsy.28 29 69 89 If used for fetal neuroprotection and patient is still experiencing preterm labor, consider short-term use of an alternative tocolytic agent.69

Tocolytic therapy may provide short-term prolongation of pregnancy (i.e., ≤48 hours) allowing time for patients to receive corticosteroids to reduce neonatal morbidity and mortality and magnesium sulfate for fetal neuroprotection and/or transfer to another (e.g., tertiary-care) facility; any other potential benefits of prolonging pregnancy are unclear.69 71 72 73

May be contraindicated by maternal or fetal conditions.69 76 (See Contraindications under Cautions.)

Do not use for >5–7 days for tocolysis; such prolonged use in pregnant women has been associated with adverse fetal effects (e.g., hypocalcemia, osteopenia, bone demineralization, fractures).75 76 77 78 79 80 81 82 83 84 85 86 (See Fetal/Neonatal Morbidity and Mortality under Cautions.)

ACOG states that maintenance treatment with tocolytic drugs is not recommended because it is not effective in preventing preterm birth and improving neonatal outcomes.69

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.19 24 25 27 69

Concurrent use of magnesium sulfate and nifedipine may be particularly risky and is potentially harmful.32 69 (See Specific Drugs under Interactions.)


Used IV successfully for the treatment of life-threatening arrhythmias such as atypical VT (torsades de pointes).h 8 9 10 400 401

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 64 401

Should not be used routinely during cardiac arrest, but may be considered when arrest rhythm is associated with torsades de pointes.400 401 402 403

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


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

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

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

Recommended by ACC/AHA for consideration in high-risk patients such as geriatric patients and/or those for whom reperfusion therapy is not suitable.64

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

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.66 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


Administer IV or IM.a 76

Also has been administered by intraosseous (IO) infusion during cardiac resuscitation when IV injection is not possible.403

When used in pregnant women for conditions other than those labeled by the FDA (e.g., prevention of preterm labor), administer only by trained obstetric personnel in a hospital setting with appropriate obstetrical care facilities.75 76 Hospitals that use magnesium sulfate for fetal neuroprotection should develop uniform and specific guidelines for such use.69 89

IV Administration

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

Rate of Administration

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


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

Use caution when switching between different parenteral formulations to ensure that patients receive the correct dose.90

Pediatric Patients

Pediatric Resuscitation
Torsades de Pointes or Suspected Hypomagnesemia

Some experts recommend 25–50 mg/kg (up to 2 g) over 10–20 minutes (or faster in torsades de pointes).403

Prevention and Control of Seizures
Acute Nephritis in Children

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


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

Additive in Total Parenteral Infusion

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

Maintenance requirements not precisely known.67


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


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


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

IV Infusion

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

Maintenance requirements are not precisely known.67


Use caution to prevent exceeding the renal excretory capacity.a


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


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

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

Administration for prolonged periods (i.e., >5–7 days) may cause adverse fetal effects.75 76 77 78 79 80 81 82 83 84 85 86 (See Fetal/Neonatal Morbidity and Mortality under Cautions.)

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 69

Atypical VT (Torsades de Pointes)

Some experts recommend 1–2 g over 15 minutes.401

Dose of 1–6 g over several minutes also used, followed in some cases by 3–20 mg/minute by IV infusion for 5–48 hours, depending on response and serum magnesium concentrations.8 9 10 64

Cardiac arrest associated with torsades de pointes: Some experts recommend 1–2 g bolus dose in 10 mL 5% dextrose injection.401


Torsades de pointes associated with cardiac arrest: Some experts recommend 1–2 g bolus dose in 10 mL 5% dextrose injection.401


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

Usually, 1.2–2 g over 20 minutes.70

Barium Poisoning

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

Pediatric Resuscitation
Torsades de Pointes

Maximum single dose of 2 g.403


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.76 f In severe renal impairment, do not exceed 20 g in a 48-hour period; monitor serum magnesium concentrations.76 f

Cautions for Magnesium Sulfate


  • Parenteral administration in heart block or myocardial damage.76 a c

  • Tocolytic therapy in general may be contraindicated by some maternal or fetal conditions (e.g., nonreassuring fetal status, chorioamnionitis, fetal demise, lethal congenital or chromosomal abnormalities, maternal bleeding with hemodynamic instability, severe preeclampsia or eclampsia, preterm premature rupture of membranes [may consider use in the absence of maternal infection for maternal transport and/or corticosteroid administration]).69

  • Tocolytic therapy with magnesium sulfate may be contraindicated in myasthenia gravis.69 72

  • In toxemia of pregnancy during 2 hours prior to delivery.67 68



Fetal/Neonatal Morbidity and Mortality

May cause fetal harm; hypocalcemia and related skeletal abnormalities (e.g., bone demineralization, osteopenia, fractures) observed in neonates with prolonged (>5–7 days) in utero exposure to parenterally administered magnesium sulfate.75 76 77 78 79 80 81 82 83 84 85 86 87 88 Evidence of such fetal toxicity based principally on case reports and epidemiologic studies.75 76 77 78 79 80 81 82 83 84 85 86 87 In these reports, magnesium sulfate was administered IV for periods >5–7 days for prevention of preterm labor (tocolysis), which is not an FDA-labeled use.75 77 78 79 80 85 86 88

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.76 87 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

If administered for preterm labor, inform patient that efficacy and safety of magnesium sulfate for this use have not been established and that use of the drug for >5–7 days in this setting may cause fetal harm.75 76 The shortest duration of use that can result in fetal harm is not known.75 76


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

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; 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

Some preparations contain aluminum; risk of aluminum accumulation and associated toxicity (e.g., CNS and bone toxicities) with prolonged parenteral administration in patients with impaired renal function.76 Premature neonates are at particularly high risk.76

Maternal Pulmonary Edema

Risk of maternal pulmonary edema with tocolytic therapy; development during the initial 24 hours is uncommon.13 69

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


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 Specific Drugs under Interactions.)

Laboratory Tests

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

Specific Populations


Category D.75 76 (See Fetal/Neonatal Morbidity and Mortality under Cautions.)

Use during pregnancy only if clearly needed; apprise patient of potential hazard to fetus.75 76

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


Distributed into milk.76 87 a Caution if used in nursing women,76 a but generally considered compatible with breast-feeding.87

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.87 a

Pediatric Use

Although one manufacturer states safety and efficacy not established in children,c other manufacturers make no pediatric restrictions.67 68 76 f g

Geriatric Use

Often requires reduced dosage because of impaired renal function.76 f (See Geriatric Patients 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, respiratory paralysis, hypocalcemia, tetany.76 a

Interactions for Magnesium Sulfate

Specific Drugs




β-Adrenergic agonists

Risk of serious adverse maternal effects when used for preterm labor69

Use concomitantly with caution69

Calcium-channel blocking agents (e.g., nifedipine)

Risk of serious adverse maternal effects (reduced heart rate, contractility, and left ventricular systolic pressure; neuromuscular blockade) when used for preterm labor69

Use concomitantly with caution69

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


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



IV administration: Immediate onset.a

IM administration: About 1 hour.a


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.



Crosses the placenta.75 76 87 a

Distributes into milk.76 87 a


Elimination Route

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





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


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


Solution CompatibilityHID


Dextrose 5% in water

Ringer’s injection, lactated

Sodium chloride 0.9%

Drug Compatibility
Admixture CompatibilityHID


Chloramphenicol sodium succinate


Heparin sodium

Hydrocortisone sodium succinate

Isoproterenol HCl


Methyldopate HCl

Norepinephrine bitartrate

Penicillin G potassium

Potassium chloride

Verapamil HCl


Amphotericin B


Dobutamine HCl

Polymyxin B sulfate


Calcium chloride

Calcium gluconate

Sodium bicarbonate

Y-Site CompatibilityHID


Acyclovir sodium



Amikacin sulfate

Ampicillin sodium



Caspofungin acetate

Cefazolin sodium

Cefotaxime sodium

Cefoxitin sodium

Chloramphenicol sodium succinate

Cisatracurium besylate

Clindamycin phosphate

Clonidine HCl


Dexmedetomidine HCl

Dobutamine HCl



Doxorubicin HCl liposome injection

Doxycycline hyclate


Erythromycin lactobionate

Esmolol HCl

Etoposide phosphate


Fenoldopam mesylate

Fludarabine phosphate

Gallium nitrate

Gentamicin sulfate

Granisetron HCl

Heparin sodium

Hetastarch in lactated electrolyte injection (Hextend)

Hydrocortisone sodium succinate

Hydromorphone HCl

Hydroxyethyl starch 130/0.4 in sodium chloride 0.9%

Idarubicin HCl

Insulin, regular

Labetalol HCl



Meperidine HCl


Micafungin sodium

Milrinone lactate

Morphine sulfate

Nafcillin sodium

Nicardipine HCl

Ondansetron HCl

Oxacillin sodium



Penicillin G potassium

Piperacillin sodium–tazobactam sodium

Potassium chloride


Remifentanil HCl


Sodium nitroprusside

Telavancin HCl


Tobramycin sulfate

Vancomycin HCl


Amphotericin B cholesteryl sulfate complex



Ceftaroline fosamil



  • 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 If administered for preterm labor, inform patient that efficacy and safety for this use have not been established and that use of the drug for >5–7 days may cause fetal harm.75 76

  • Importance of informing patients of other important precautionary information.76 a (See Cautions.)


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

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

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

Magnesium Sulfate


Dosage Forms


Brand Names







Magnesium Sulfate Injection

Injection, for IV use only

4% (4, 20, and 40 g)*

Magnesium Sulfate Injection

8% (4 g)*

Magnesium Sulfate Injection

Magnesium Sulfate in Dextrose


Dosage Forms


Brand Names



Injection, for IV use only

1% (1 g) in 5% Dextrose*

Magnesium Sulfate in 5% Dextrose Injection

AHFS DI Essentials. © Copyright 2017, Selected Revisions January 19, 2017. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

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


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