Magnesium Sulfate 50% Inj, 20ml
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
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 or treat seizures in pregnant women with pre-eclampsia or eclampsia, and sometimes for severe asthma attacks or 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.
If you need to store this medication at home, consult with your doctor, nurse, or pharmacist to determine the proper storage procedure.
If you miss a dose, contact your doctor immediately to receive guidance on the appropriate course of action.
If you need to store this medication at home, consult with your doctor, nurse, or pharmacist to determine the proper storage procedure.
If you miss a dose, contact your doctor immediately to receive guidance on the appropriate course of action.
Lifestyle & Tips
- Report any changes in breathing, muscle weakness, or feeling very sleepy.
- Inform healthcare providers about all medications, supplements, and medical conditions.
- Avoid alcohol and other sedatives unless approved by a doctor, as they can increase drowsiness.
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 eclampsia: 4-5 g IV loading dose over 15-20 min, followed by 1-2 g/hour continuous IV infusion. For hypomagnesemia (severe): 8-12 g IV over 5-6 hours. For Torsades de Pointes: 1-2 g IV over 5-20 min, may repeat.
Dose Range:
1 - 12 mg
Condition-Specific Dosing:
Eclampsia/Pre-eclampsia:
Loading dose: 4-5 g IV over 15-20 min. Maintenance: 1-2 g/hour continuous IV infusion. Max 30-40 g/24 hours.
Hypomagnesemia (severe):
8-12 g IV over 5-6 hours, or 1-2 g/hour for 5-10 hours. Total daily dose up to 40 g.
Torsades de Pointes:
1-2 g IV over 5-20 min, may repeat once.
Acute severe asthma:
2 g IV over 20 minutes.
Pediatric Dosing
Neonatal:
Hypomagnesemia: 25-50 mg/kg/dose IV over 2-4 hours, repeat every 8-12 hours for 2-3 doses. Max 2000 mg/day. Neonatal seizures (hypomagnesemic): 25-50 mg/kg IV over 15-30 min.
Infant:
Hypomagnesemia: 25-50 mg/kg/dose IV over 2-4 hours, repeat every 8-12 hours for 2-3 doses. Max 2000 mg/day. Acute severe asthma: 25-50 mg/kg IV over 10-20 min (max 2 g).
Child:
Hypomagnesemia: 25-50 mg/kg/dose IV over 2-4 hours, repeat every 8-12 hours for 2-3 doses. Max 2000 mg/day. Acute severe asthma: 25-50 mg/kg IV over 10-20 min (max 2 g).
Adolescent:
Hypomagnesemia: 25-50 mg/kg/dose IV over 2-4 hours, repeat every 8-12 hours for 2-3 doses. Max 2000 mg/day. Acute severe asthma: 25-50 mg/kg IV over 10-20 min (max 2 g).
Dose Adjustments
Renal Impairment:
Mild:
CrCl 30-50 mL/min: Reduce dose by 25-50%. Monitor magnesium levels closely.
Moderate:
CrCl 10-30 mL/min: Reduce dose by 50-75%. Monitor magnesium levels closely. Avoid if possible.
Severe:
CrCl <10 mL/min: Contraindicated or use with extreme caution at significantly reduced doses (e.g., 50% or more reduction) with frequent magnesium level monitoring. Risk of toxicity is high.
Dialysis:
Magnesium is dialyzable. Avoid administration if possible. If necessary, administer post-dialysis and monitor levels closely. Dose reduction is required.
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 many enzyme systems, including those involved in ATP production, nucleic acid synthesis, and muscle contraction. It acts as a physiological calcium channel blocker, reducing the influx of calcium into cells. In the CNS, it depresses the central nervous system and blocks peripheral neuromuscular transmission, leading to anticonvulsant effects. In smooth muscle, it causes relaxation, leading to bronchodilation and vasodilation. It also reduces acetylcholine release at the neuromuscular junction.
Pharmacokinetics
Absorption:
Bioavailability:
100% (IV)
Tmax:
Immediate (IV)
FoodEffect:
Not applicable for IV formulation
Distribution:
Vd:
0.2-0.3 L/kg (distributes into extracellular fluid and bone)
ProteinBinding:
Approximately 30% (to albumin)
CnssPenetration:
Limited (crosses blood-brain barrier slowly, but therapeutic levels can be achieved)
Elimination:
HalfLife:
Approximately 2-4 hours (in patients with normal renal function)
Clearance:
Primarily renal
ExcretionRoute:
Renal (glomerular filtration)
Unchanged:
Nearly 100%
Pharmacodynamics
OnsetOfAction:
Immediate (IV)
PeakEffect:
Minutes (IV)
DurationOfAction:
Approximately 30 minutes (IV, single dose); continuous infusion maintains effect as long as infused.
Safety & Warnings
BLACK BOX WARNING
Continuous intravenous administration of magnesium sulfate to pregnant women for more than 5 to 7 days can result in hypocalcemia and bone abnormalities in the developing fetus. These bone abnormalities have included skeletal demineralization and osteopenia. In addition, several cases of neonatal rickets have been reported. Therefore, magnesium sulfate should be used for short-term tocolysis only when the benefits clearly outweigh the risks.
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
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 help right away, 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 notice any symptoms that bother you or persist.
Not all possible side effects are listed here. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
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 help right away, 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 notice any symptoms that bother you or persist.
Not all possible side effects are listed here. If you have questions or concerns about side effects, consult 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:
- Difficulty breathing or very slow breathing
- Feeling very weak or floppy
- Extreme drowsiness or difficulty waking up
- Blurred vision
- Slurred speech
- Feeling very warm or flushed
- No urine output
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 symptoms you experienced.
If you have a heart block or any pre-existing heart problems.
* If you are currently taking nifedipine or terbutaline, as these medications may interact with this drug.
Please note that this is not an exhaustive list of all potential interactions. To ensure your safety, it is crucial to disclose all of your medications, including prescription and over-the-counter drugs, natural products, and vitamins, as well as any health issues you may have. Your doctor and pharmacist need this information to determine whether it is safe for you to take this medication in conjunction with your other treatments.
Remember, do not start, stop, or adjust 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 symptoms you experienced.
If you have a heart block or any pre-existing heart problems.
* If you are currently taking nifedipine or terbutaline, as these medications may interact with this drug.
Please note that this is not an exhaustive list of all potential interactions. To ensure your safety, it is crucial to disclose all of your medications, including prescription and over-the-counter drugs, natural products, and vitamins, as well as any health issues you may have. Your doctor and pharmacist need this information to determine whether it is safe for you to take this medication in conjunction with your other treatments.
Remember, do not start, stop, or adjust 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 discuss any concerns or questions you may have.
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.
Do not take this medication if you have myasthenia gravis, as it can cause severe and potentially life-threatening breathing problems in people with this condition.
If you are pregnant or become pregnant while taking this medication, immediately contact your doctor, as it may harm the unborn baby. Additionally, if you are breastfeeding, consult with your doctor to discuss any 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 discuss any concerns or questions you may have.
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.
Do not take this medication if you have myasthenia gravis, as it can cause severe and potentially life-threatening breathing problems in people with this condition.
If you are pregnant or become pregnant while taking this medication, immediately contact your doctor, as it may harm the unborn baby. Additionally, if you are breastfeeding, consult with your doctor to discuss any potential risks to your baby and determine the best course of action.
Overdose Information
Overdose Symptoms:
- Hypotension (low blood pressure)
- Bradycardia (slow heart rate)
- Respiratory depression (slow, shallow breathing)
- Loss of deep tendon reflexes (e.g., knee jerk)
- Muscle paralysis
- Coma
- Cardiac arrest
What to Do:
Immediately discontinue magnesium sulfate. Administer intravenous calcium gluconate (10 mL of 10% solution) slowly to counteract magnesium's effects. Provide respiratory support (e.g., mechanical ventilation) if needed. Administer IV fluids to promote renal excretion. Dialysis may be necessary in severe cases, especially 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 or increased paralysis and respiratory depression.
- Calcium channel blockers (e.g., nifedipine, verapamil): May enhance hypotensive and neuromuscular effects.
- CNS depressants (e.g., opioids, benzodiazepines, barbiturates): Additive CNS depression, increased risk of respiratory depression and sedation.
- Digoxin: High magnesium levels can interfere with digoxin's cardiac effects and increase risk of toxicity in some cases.
Moderate Interactions
- Diuretics (loop and thiazide): May increase renal excretion of magnesium, potentially leading to hypomagnesemia (though magnesium sulfate is given to treat hypomagnesemia, this is a general interaction for magnesium).
- Aminoglycosides: May enhance neuromuscular blockade.
- Potassium-sparing diuretics: Risk of hyperkalemia if renal function is impaired.
Minor Interactions
- Tetracyclines/Quinolones (oral): Magnesium can chelate these antibiotics, reducing their absorption (not relevant for IV magnesium sulfate).
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.
Baseline vital signs (BP, HR, RR)
Rationale: To establish baseline and monitor for adverse effects.
Timing: Prior to initiation.
Deep Tendon Reflexes (DTRs)
Rationale: Loss of DTRs is an early sign of hypermagnesemia.
Timing: Prior to initiation.
Serum Magnesium levels
Rationale: To establish baseline and guide dosing, especially in hypomagnesemia.
Timing: Prior to initiation.
Routine Monitoring
Serum Magnesium levels
Frequency: Every 4-6 hours during continuous infusion, or as clinically indicated.
Target: Therapeutic range for eclampsia: 4-7 mEq/L (4.8-8.4 mg/dL). Normal range: 1.5-2.5 mEq/L (1.8-3.0 mg/dL).
Action Threshold: >7 mEq/L (loss of DTRs), >10 mEq/L (respiratory depression), >12 mEq/L (cardiac arrest).
Vital signs (BP, HR, RR)
Frequency: Every 15-60 minutes during loading dose, then hourly during maintenance infusion.
Target: Maintain within patient's normal range.
Action Threshold: Significant hypotension, bradycardia, or respiratory rate <12 breaths/min.
Deep Tendon Reflexes (DTRs)
Frequency: Hourly during continuous infusion.
Target: Present (2+).
Action Threshold: Absent DTRs (especially patellar reflex).
Urine output
Frequency: Hourly.
Target: >25-30 mL/hour (adult).
Action Threshold: <25 mL/hour for 2 consecutive hours (indicates impaired renal excretion and increased risk of toxicity).
Level of consciousness
Frequency: Hourly.
Target: Alert and oriented.
Action Threshold: Increased somnolence, lethargy.
Symptom Monitoring
- Respiratory depression (slow, shallow breathing)
- Hyporeflexia or absent deep tendon reflexes
- Hypotension
- Bradycardia
- Flushing
- Sweating
- Sedation/Lethargy
- Muscle weakness
- Nausea/Vomiting
- Blurred vision
- Slurred speech
Special Patient Groups
Pregnancy
Category D. Used for prevention and control of seizures in severe pre-eclampsia and eclampsia. Prolonged use (more than 5-7 days) for tocolysis (off-label) is associated with fetal hypocalcemia and bone abnormalities (osteopenia, rickets). Should be used with caution and only when clearly indicated.
Trimester-Specific Risks:
First Trimester:
Limited data on first trimester exposure. Generally not used for pre-eclampsia/eclampsia in the first trimester.
Second Trimester:
Used for pre-eclampsia/eclampsia if indicated. Risk of fetal bone abnormalities with prolonged exposure.
Third Trimester:
Used for pre-eclampsia/eclampsia. Risk of fetal bone abnormalities with prolonged exposure. Neonatal hypotonia, respiratory depression, and hyporeflexia can occur if administered close to delivery.
Lactation
L3 - Moderately safe. Magnesium is a normal component of breast milk. While maternal magnesium levels may increase with therapy, the amount transferred to breast milk 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 sensitive infants.
Pediatric Use
Dosing is weight-based and varies by indication. Close monitoring of magnesium levels, vital signs, and DTRs is crucial due to higher risk of toxicity in neonates and infants, especially with renal immaturity. Used for hypomagnesemia, acute severe asthma, and certain arrhythmias.
Geriatric Use
Use with caution due to potential for age-related decline in renal function, which increases the risk of hypermagnesemia. Start with lower doses and monitor magnesium levels, renal function, and vital signs closely. Elderly patients may be more sensitive to CNS depressant effects.
Clinical Information
Clinical Pearls
- Always have calcium gluconate readily available as an antidote for magnesium toxicity.
- Monitor urine output closely; oliguria is a contraindication to continued magnesium sulfate infusion due to increased risk of toxicity.
- Assess deep tendon reflexes (patellar reflex) frequently; loss of DTRs is an early sign of hypermagnesemia.
- Respiratory rate is a critical vital sign to monitor; respiratory depression is a serious complication of hypermagnesemia.
- Magnesium sulfate is a high-alert medication; ensure correct concentration, dose, and infusion rate.
- For obstetrical use, the goal is to achieve therapeutic magnesium levels (4-7 mEq/L) to prevent seizures, not to lower blood pressure (though it may have a mild hypotensive effect).
Alternative Therapies
- For eclampsia/pre-eclampsia: Other anticonvulsants (e.g., phenytoin, benzodiazepines) are less preferred but may be used if magnesium is contraindicated or ineffective.
- For hypomagnesemia: Oral magnesium supplements for mild cases.
- For Torsades de Pointes: Isoproterenol, overdrive pacing.
- For acute severe asthma: Beta-agonists, corticosteroids, anticholinergics.
Cost & Coverage
Average Cost:
Low cost (generic) per 20ml vial (10g)
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 promptly. To ensure safe use, never share your medication with others or take someone else's medication. 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; do not flush them down the toilet or pour them down the drain unless instructed to do so by a healthcare professional or pharmacist. If you are unsure about the correct 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 emergency medical attention. Be prepared to provide information about the medication taken, the quantity, and the time of ingestion.