Magnesium Sulfate Dilution for Mild Magnesium Deficiency
For mild magnesium deficiency, magnesium sulfate should be diluted in saline to a concentration of 20% or less prior to administration, with 5 g (approximately 40 mEq) added to one liter of 0.9% Sodium Chloride for slow IV infusion over a three-hour period. 1
IV Administration Guidelines
- For mild magnesium deficiency, the standard adult dose is 1 g of magnesium sulfate (equivalent to 8.12 mEq of magnesium) diluted in saline and administered intravenously 1
- Solutions for IV infusion must be diluted to a concentration of 20% or less prior to administration 1
- Common diluents include 5% Dextrose Injection and 0.9% Sodium Chloride Injection 1
- For severe hypomagnesemia, 5 g (approximately 40 mEq) can be added to one liter of 0.9% Sodium Chloride for slow IV infusion over a three-hour period 1
Alternative Administration Methods
- For mild deficiency, 1 g of magnesium sulfate (equivalent to 8.12 mEq) can be administered intramuscularly every six hours for four doses 1
- Oral magnesium oxide at a dose of 12-24 mmol daily is recommended for mild hypomagnesemia when IV administration is not necessary 2
- Administering oral magnesium at night when intestinal transit is slowest can help maximize absorption 2
Monitoring and Safety Considerations
- Dosage must be carefully adjusted according to individual requirements and response 1
- The rate of IV injection should generally not exceed 150 mg/minute 1
- Monitor for signs of magnesium toxicity, including hypotension, drowsiness, and muscle weakness 2
- In patients with renal insufficiency, the maximum dosage should be reduced and frequent serum magnesium concentrations must be obtained 1
Special Clinical Scenarios
- For patients with short bowel syndrome or malabsorption, higher doses or parenteral supplementation may be required 3
- In patients with high-output stoma, first correct water and sodium depletion to address secondary hyperaldosteronism, which can worsen magnesium deficiency 2
- Hypokalaemia associated with hypomagnesaemia is resistant to potassium treatment but responds to magnesium replacement 4
Important Considerations
- Administration of the drug should be discontinued as soon as the desired effect is obtained 1
- IV administration provides therapeutic levels almost immediately, while IM administration of undiluted 50% solution results in therapeutic plasma levels in 60 minutes 1
- Most magnesium salts are poorly absorbed orally and may worsen diarrhea or stomal output in patients with gastrointestinal disorders 2
- Intravenous infusion of magnesium sulfate has been shown to be safe with no significant deleterious effects on cardiovascular, liver, kidney, or metabolic function 5