Magnesium Su 40g/1000ml Inj, 1000ml
It is used to treat or prevent low magnesium levels.It is used to prevent and control seizures during pregnancy.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Anticonvulsant; Electrolyte Supplement; Tocolytic
Pharmacologic Class
Mineral; Electrolyte; CNS Depressant
Pregnancy Category
Category D
FDA Approved
Jan 1970
DEA Schedule
Not Controlled
Overview
What is this medicine?
Magnesium sulfate is a mineral given by injection to treat low magnesium levels, prevent seizures in pregnant women with severe high blood pressure (pre-eclampsia/eclampsia), or treat certain heart rhythm problems. It works by relaxing muscles and calming the nervous system.
How to Use This Medicine
To use this medication correctly, follow your doctor's instructions and carefully read all accompanying information. Take this medication exactly as directed, and adhere to all guidelines provided. This medication is administered either as an intramuscular injection or as an intravenous infusion, which is given over a specified period of time.
For proper storage and disposal of this medication, consult with your doctor, nurse, or pharmacist to determine the best approach if you need to store it at home.
If you miss a dose, contact your doctor immediately to receive guidance on the appropriate course of action.
For proper storage and disposal of this medication, consult with your doctor, nurse, or pharmacist to determine the best approach if you need to store it at home.
If you miss a dose, contact your doctor immediately to receive guidance on the appropriate course of action.
Lifestyle & Tips
- Report any unusual symptoms immediately to your healthcare provider.
- Inform your doctor about all medications you are taking, including over-the-counter drugs and supplements.
- Avoid alcohol and other sedatives while receiving magnesium sulfate, as they can increase drowsiness and breathing problems.
Available Forms & Alternatives
Available Strengths:
- Magnesium Oxide 400mg Tablets
- Magnesium Sulfate 50% Inj, 10ml
- Magnesium 500mg Tablets
- Magnesium Sulfate 40mg/ml Inj, 50ml
- Magnesium Chloride 20% Inj, 50ml
- Magnesium Sulf 40mg/ml Inj, 100ml
- Magnesium Sulfate 50% Inj, 50ml
- Magnesium 200mg Tablets
- Magnesium Sulfate 50% Inj, 2ml
- Magnesium 300mg Capsules
- Magnesium Sulfate 40mg/ml Inj, 50ml
- Magnesium Sulfate 80mg/ml Inj, 50ml
- Magnesium 250mg Tablets
- Magnesium Sulfate 80mg/ml Inj
- Magn Sulf/d5w 10mg/ml Inj, 100ml
- Magnesium Oxide 250mg Tablets
- Magnesium Citrate Soln Lemon 296ml
- Magnesium Sulfate 50% Inj, 20ml
- Magnesium Su 40g/1000ml Inj, 1000ml
- Magnesium Sulfate 20gm/500ml Inj
Dosing & Administration
Adult Dosing
Standard Dose:
Varies significantly by indication. For severe hypomagnesemia: 8-12 g IV over 24 hours. For eclampsia: 4-5 g IV load, then 1-2 g/hour IV infusion.
Dose Range:
1 - 12 mg
Condition-Specific Dosing:
eclampsia:
Loading dose: 4-5 g IV over 15-30 minutes, followed by a continuous infusion of 1-2 g/hour. Max 30-40 g/24 hours.
pre-eclampsia (severe):
Loading dose: 4-5 g IV over 15-30 minutes, followed by a continuous infusion of 1-2 g/hour.
hypomagnesemia (severe):
8-12 g IV over 24 hours (e.g., 1-2 g/hour for 6-12 hours, then 1 g/hour).
torsades de pointes:
1-2 g IV over 5-20 minutes, may repeat once.
acute asthma exacerbation:
2 g IV over 20 minutes (for severe exacerbations not responding to standard therapy).
Pediatric Dosing
Neonatal:
Neuroprotection (preterm labor): 4 g IV over 20-30 minutes to mother prior to delivery. For hypomagnesemia: 25-50 mg/kg/dose IV over 2-4 hours, repeat every 8-12 hours for 2-3 doses.
Infant:
Hypomagnesemia: 25-50 mg/kg/dose IV over 2-4 hours, repeat every 8-12 hours for 2-3 doses. Max 2 g/day.
Child:
Hypomagnesemia: 25-50 mg/kg/dose IV over 2-4 hours, repeat every 8-12 hours for 2-3 doses. Max 2 g/day. Acute asthma: 25-50 mg/kg IV over 10-20 minutes (max 2 g).
Adolescent:
Similar to adult dosing for specific indications (e.g., acute asthma, hypomagnesemia).
Dose Adjustments
Renal Impairment:
Mild:
Reduce dose by 25-50% or extend dosing interval.
Moderate:
Reduce dose by 50% or extend dosing interval. Monitor serum magnesium levels closely.
Severe:
Contraindicated or significantly reduced dose (e.g., 50-75% reduction) with extreme caution and continuous monitoring of serum magnesium, DTRs, and respiratory rate. Risk of toxicity is high.
Dialysis:
Magnesium is dialyzable. Avoid or use with extreme caution and close monitoring. Dosing post-dialysis may be required based on serum levels.
Hepatic Impairment:
Mild:
No specific adjustment needed.
Moderate:
No specific adjustment needed.
Severe:
No specific adjustment needed.
Pharmacology
Mechanism of Action
Magnesium is an essential cofactor for numerous enzymatic reactions, including those involved in energy production, nucleic acid synthesis, and protein synthesis. As a CNS depressant, it blocks neuromuscular transmission by decreasing acetylcholine release at the motor end plate. It also has direct depressant effects on the CNS and smooth muscle, including uterine muscle, and acts as a peripheral vasodilator. In Torsades de Pointes, it is thought to block calcium influx into myocardial cells and stabilize cardiac membranes.
Pharmacokinetics
Absorption:
Bioavailability:
100% (IV)
Tmax:
Immediate (IV)
FoodEffect:
Not applicable (IV)
Distribution:
Vd:
0.2-0.3 L/kg
ProteinBinding:
Approximately 30% (to albumin)
CnssPenetration:
Limited (crosses blood-brain barrier slowly)
Elimination:
HalfLife:
Approximately 2-4 hours (normal renal function)
Clearance:
Primarily renal excretion
ExcretionRoute:
Renal (glomerular filtration)
Unchanged:
Nearly 100%
Pharmacodynamics
OnsetOfAction:
Immediate (IV)
PeakEffect:
Minutes (IV)
DurationOfAction:
Approximately 30 minutes (IV bolus); 3-4 hours (IV infusion, depending on renal function)
Safety & Warnings
BLACK BOX WARNING
Continuous intravenous administration of magnesium sulfate to pregnant women for more than 5-7 days for preterm labor has resulted in fetal bone abnormalities. Magnesium sulfate is not approved for prolonged tocolysis.
Side Effects
Urgent Side Effects: Seek Medical Attention Immediately
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical help right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of high magnesium levels, including:
+ Confusion
+ Feeling sluggish
+ Slow movements
+ Shortness of breath
+ Upset stomach
+ Severe dizziness or passing out
Signs of low calcium levels, such as:
+ Muscle cramps or spasms
+ Numbness and tingling
+ Seizures
Other severe side effects, including:
+ Slow heartbeat
+ Flushing
+ Inability to move
+ Changes in eyesight
+ Feeling cold
+ Excessive sweating
If you experience any of the following symptoms, seek medical attention immediately, as they could be signs of a life-threatening muscle problem:
New or worsening muscle weakness
Trouble chewing or swallowing
Trouble breathing
Droopy eyelids
* Changes in eyesight, such as blurred vision or double vision
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to contact your doctor or seek medical help if you have any side effects that bother you or do not go away.
Not all possible side effects are listed here. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical help right away:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of high magnesium levels, including:
+ Confusion
+ Feeling sluggish
+ Slow movements
+ Shortness of breath
+ Upset stomach
+ Severe dizziness or passing out
Signs of low calcium levels, such as:
+ Muscle cramps or spasms
+ Numbness and tingling
+ Seizures
Other severe side effects, including:
+ Slow heartbeat
+ Flushing
+ Inability to move
+ Changes in eyesight
+ Feeling cold
+ Excessive sweating
If you experience any of the following symptoms, seek medical attention immediately, as they could be signs of a life-threatening muscle problem:
New or worsening muscle weakness
Trouble chewing or swallowing
Trouble breathing
Droopy eyelids
* Changes in eyesight, such as blurred vision or double vision
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to contact your doctor or seek medical help if you have any side effects that bother you or do not go away.
Not all possible side effects are listed here. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Feeling very sleepy or weak
- Difficulty breathing or slow breathing
- Muscle weakness or inability to move
- Blurred or double vision
- Slurred speech
- Feeling dizzy or lightheaded
- Very low blood pressure
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
If you have a heart block or any other heart problems.
* If you are currently taking nifedipine or terbutaline, as these medications may interact with this drug.
This list is not exhaustive, and it is crucial to disclose all your medications, including prescription and over-the-counter drugs, natural products, and vitamins, to your doctor and pharmacist. This will help ensure that it is safe for you to take this medication in conjunction with your other medications and health conditions.
Remember, do not start, stop, or change the dosage of any medication without first consulting your doctor to confirm that it is safe to do so.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
If you have a heart block or any other heart problems.
* If you are currently taking nifedipine or terbutaline, as these medications may interact with this drug.
This list is not exhaustive, and it is crucial to disclose all your medications, including prescription and over-the-counter drugs, natural products, and vitamins, to your doctor and pharmacist. This will help ensure that it is safe for you to take this medication in conjunction with your other medications and health conditions.
Remember, do not start, stop, or change the dosage of any medication without first consulting your doctor to confirm that it is safe to do so.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. If you are following a low-magnesium diet, consult with your doctor to discuss any potential interactions.
Regular blood tests will be necessary, as directed by your doctor, to monitor your condition. Be sure to follow your doctor's instructions for scheduling these tests and discussing the results.
This medication may contain aluminum, which can increase the risk of aluminum toxicity with long-term use. This risk is particularly higher if you have kidney problems or if you are a premature infant. It is crucial to discuss this potential risk with your doctor.
If you have myasthenia gravis, do not take this medication, as it can cause severe and potentially life-threatening breathing problems in people with this condition.
Additionally, if you are pregnant or become pregnant while taking this medication, you should contact your doctor immediately, as it may harm the unborn baby.
If you are breast-feeding, inform your doctor, as you will need to discuss the potential risks to your baby and determine the best course of action.
Regular blood tests will be necessary, as directed by your doctor, to monitor your condition. Be sure to follow your doctor's instructions for scheduling these tests and discussing the results.
This medication may contain aluminum, which can increase the risk of aluminum toxicity with long-term use. This risk is particularly higher if you have kidney problems or if you are a premature infant. It is crucial to discuss this potential risk with your doctor.
If you have myasthenia gravis, do not take this medication, as it can cause severe and potentially life-threatening breathing problems in people with this condition.
Additionally, if you are pregnant or become pregnant while taking this medication, you should contact your doctor immediately, as it may harm the unborn baby.
If you are breast-feeding, inform your doctor, as you will need to discuss the potential risks to your baby and determine the best course of action.
Overdose Information
Overdose Symptoms:
- Loss of deep tendon reflexes (e.g., knee jerk)
- Respiratory depression (slow, shallow breathing)
- Profound muscle weakness or paralysis
- Hypotension (low blood pressure)
- Bradycardia (slow heart rate)
- ECG changes (prolonged PR, QRS, QT intervals)
- Cardiac arrest
What to Do:
Immediate discontinuation of magnesium sulfate. Administer intravenous calcium gluconate (10 mL of 10% solution) slowly to reverse respiratory depression and cardiac effects. Provide respiratory support (e.g., mechanical ventilation) if needed. Dialysis may be considered in severe cases with renal impairment. Call 1-800-222-1222 (Poison Control).
Drug Interactions
Major Interactions
- Neuromuscular blockers (e.g., rocuronium, vecuronium): Potentiates neuromuscular blockade, leading to prolonged paralysis and respiratory depression.
- Calcium channel blockers (e.g., nifedipine, verapamil): Increased risk of hypotension and bradycardia.
- CNS depressants (e.g., opioids, benzodiazepines, general anesthetics): Additive CNS depression, increased risk of respiratory depression and sedation.
Moderate Interactions
- Digoxin: Magnesium deficiency can increase digoxin toxicity; however, high magnesium levels can also affect digoxin levels or effects.
- Diuretics (loop and thiazide): May increase renal excretion of magnesium, potentially leading to hypomagnesemia.
- Aminoglycosides: May potentiate neuromuscular blockade.
- Potassium-sparing diuretics: Risk of hyperkalemia if renal function is impaired.
Minor Interactions
- Tetracyclines/Quinolones (oral): Magnesium can chelate these antibiotics, reducing absorption (not relevant for IV magnesium).
Monitoring
Baseline Monitoring
Renal function (BUN, creatinine)
Rationale: Magnesium is primarily renally excreted; impaired renal function increases risk of toxicity.
Timing: Prior to initiation of therapy.
Serum magnesium levels
Rationale: To establish baseline and guide initial dosing, especially in hypomagnesemia.
Timing: Prior to initiation of therapy.
Electrolytes (Potassium, Calcium)
Rationale: Magnesium imbalances can affect other electrolytes; hypokalemia and hypocalcemia often co-exist with hypomagnesemia.
Timing: Prior to initiation of therapy.
Routine Monitoring
Serum magnesium levels
Frequency: Every 4-6 hours during continuous infusion, or as clinically indicated.
Target: Therapeutic range varies by indication (e.g., 4-7 mEq/L for eclampsia, 1.5-2.5 mEq/L for hypomagnesemia).
Action Threshold: Levels > 7 mEq/L (loss of DTRs), > 10 mEq/L (respiratory depression), > 12 mEq/L (cardiac arrest).
Deep Tendon Reflexes (DTRs)
Frequency: Hourly during continuous infusion, or every 1-2 hours.
Target: Present (2+)
Action Threshold: Absent DTRs indicate impending toxicity; reduce or hold dose.
Respiratory Rate
Frequency: Hourly during continuous infusion, or every 1-2 hours.
Target: > 12 breaths/minute
Action Threshold: < 12 breaths/minute indicates significant toxicity; hold dose, consider antidote.
Urine Output
Frequency: Hourly during continuous infusion.
Target: > 25-30 mL/hour or > 100 mL/4 hours
Action Threshold: < 25 mL/hour indicates impaired renal excretion and increased risk of toxicity; reduce or hold dose.
Blood Pressure
Frequency: Hourly during continuous infusion.
Target: Within target range for indication (e.g., normotensive or controlled hypertension)
Action Threshold: Significant hypotension; reduce or hold dose.
ECG monitoring
Frequency: Continuous or frequent, especially with rapid infusion or high doses.
Target: Normal sinus rhythm, no prolonged PR/QT intervals, no widened QRS.
Action Threshold: Bradycardia, heart block, prolonged PR/QT, widened QRS, asystole.
Symptom Monitoring
- Lethargy
- Drowsiness
- Muscle weakness
- Flushing
- Sweating
- Hypotension
- Bradycardia
- Nausea
- Vomiting
- Slurred speech
- Double vision
- Respiratory depression
- Cardiac arrest
Special Patient Groups
Pregnancy
Category D. Used for prevention and treatment of seizures in severe pre-eclampsia and eclampsia, and for neuroprotection of the fetus in anticipated preterm birth. Prolonged use (>5-7 days) for preterm labor is associated with fetal bone abnormalities and is not recommended.
Trimester-Specific Risks:
First Trimester:
Generally avoided unless critically indicated due to limited data, but not typically used for its primary indications in the first trimester.
Second Trimester:
Used for pre-eclampsia/eclampsia and neuroprotection in preterm labor. Risk of fetal bone abnormalities with prolonged exposure.
Third Trimester:
Commonly used for pre-eclampsia/eclampsia and neuroprotection in preterm labor. Risk of fetal bone abnormalities with prolonged exposure. Neonatal hypotonia and respiratory depression can occur if administered close to delivery.
Lactation
L3 (Moderately Safe). Magnesium is naturally present in breast milk. While IV magnesium sulfate can increase milk magnesium levels, the amount transferred to the infant is generally considered low and unlikely to cause adverse effects in a healthy, full-term infant. Monitor infant for signs of diarrhea or sedation.
Infant Risk:
Low risk for healthy, full-term infants. Potential for mild diarrhea or sedation in preterm or compromised infants.
Pediatric Use
Used for severe hypomagnesemia, acute severe asthma, and Torsades de Pointes. Dosing is weight-based. Close monitoring of magnesium levels, vital signs, and DTRs is crucial due to higher risk of toxicity in neonates and infants.
Geriatric Use
Use with caution due to potential for age-related decline in renal function, which increases the risk of magnesium accumulation and toxicity. Start with lower doses and monitor closely for signs of hypermagnesemia (e.g., muscle weakness, respiratory depression, hypotension).
Clinical Information
Clinical Pearls
- Always have calcium gluconate (10% solution) readily available as an antidote for magnesium toxicity.
- Monitor deep tendon reflexes (DTRs) and respiratory rate frequently; loss of DTRs is often the first sign of toxicity.
- Ensure adequate urine output before and during magnesium administration, as renal excretion is the primary elimination route.
- Magnesium sulfate is a high-alert medication; verify dose, rate, and patient monitoring parameters carefully.
- For eclampsia, magnesium sulfate is superior to other anticonvulsants for seizure prevention and treatment.
- Rapid IV push can cause hypotension and cardiac arrest; always administer as a slow IV infusion or bolus over recommended time.
Alternative Therapies
- For hypomagnesemia: Oral magnesium supplements (for mild cases).
- For eclampsia/pre-eclampsia: Antihypertensives (e.g., labetalol, hydralazine) for blood pressure control, but magnesium is the drug of choice for seizure prophylaxis/treatment.
- For Torsades de Pointes: Isoproterenol, overdrive pacing (if magnesium is ineffective or contraindicated).
- For acute asthma: Beta-agonists, corticosteroids, anticholinergics.
Cost & Coverage
Average Cost:
Varies widely, typically low cost per 1000ml bag
Generic Available:
Yes
Insurance Coverage:
Tier 1 (Generic)
General Drug Facts
If your symptoms or health problems persist or worsen, it is essential to contact your doctor for further guidance. To ensure safe use, never share your medication with others, and do not take medication prescribed for someone else. Store all medications in a secure location, out of reach of children and pets, to prevent accidental ingestion. Dispose of unused or expired medications properly. Unless instructed to do so by a healthcare professional, do not flush medications down the toilet or pour them down the drain. If you are unsure about the proper disposal method, consult your pharmacist, who can also inform you about potential drug take-back programs in your area. Some medications may come with an additional patient information leaflet, which your pharmacist can provide. If you have any questions or concerns about your medication, discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately contact your local poison control center or seek medical attention. Be prepared to provide information about the medication taken, the amount, and the time it was taken to ensure prompt and effective treatment.