Appropriate Dosage of Magnex Forte (Magnesium) for Treatment
For treatment of hypomagnesemia, the recommended dosage of Magnex forte (magnesium) is 500mg to 1g daily, with specific dosing adjusted based on the condition being treated and patient factors such as renal function. 1
Dosage Guidelines by Indication
General Hypomagnesemia Treatment
- Standard therapeutic range: 500mg to 1g elemental magnesium daily 1
- For adults: 350mg daily for women and 420mg daily for men as maintenance dosing 1
Specific Clinical Scenarios
Severe Asthma
- IV magnesium sulfate: 2g administered over 20 minutes for patients with severe refractory asthma 2
- This dosage has been shown to improve pulmonary function and reduce hospital admissions
Cardiac Conditions
- Acute cardiotoxicity: 1-2g IV magnesium sulfate bolus 1
- Maintenance therapy: Oral magnesium oxide 12-24 mmol (480-960mg) daily 1
Constipation
- Magnesium hydroxide (Milk of Magnesia): 2400mg per 30mL dose 3
- For chronic idiopathic constipation: 400-500mg of magnesium daily 1
Administration Considerations
Formulation Selection
- Magnesium oxide: Commonly used for inpatient settings, typically administered at night to maximize absorption 1
- Magnesium citrate: Effective but contraindicated in patients with congestive heart failure due to hyperosmolar nature 1
- Magnesium glycinate: 500mg before bedtime for patients with sleep disorders 1
- Magnesium hydroxide: Available as 400mg per 5mL suspension (Milk of Magnesia) 3
Timing and Administration
- For oral supplementation, administration at night may maximize absorption 1
- Higher doses may be required in patients taking H2-receptor antagonists or proton pump inhibitors 1
- For IV administration, magnesium should be administered slowly (over 15-20 minutes) to avoid adverse effects 2, 1
Monitoring and Safety Considerations
Before Starting Therapy
- Check baseline serum magnesium, potassium, and renal function 1
- Correct sodium and water depletion and secondary hyperaldosteronism before magnesium replacement 1
During Therapy
- Follow-up serum magnesium levels 1-2 weeks after initiation 1
- Periodic monitoring (every 3-6 months) for long-term supplementation 1
- Monitor for gastrointestinal side effects (diarrhea, abdominal cramping, nausea) 1
Contraindications and Precautions
- Renal impairment: Magnesium supplements are contraindicated in patients with significant renal insufficiency 1
- Cardiac conditions: Monitor for ECG changes, AV nodal conduction block, bradycardia, and hypotension 1
- Elderly patients: Monitor for hyponatremia with magnesium citrate supplementation 1
Special Considerations
Parenteral Nutrition
- For patients receiving parenteral nutrition, the recommended provision is 1 mmol (55 mg)/day 2
- Manganese contamination should be limited to less than 40 μg/d total in a typical adult PN formula 2
Malnourished Patients
- In severely malnourished patients, magnesium should be repleted slowly along with other electrolytes to prevent refeeding syndrome 1
Drug Interactions
- Use with caution in patients taking medications that may interact with magnesium 1
- Hypokalaemia resistant to potassium treatment may respond to magnesium replacement 1
By following these dosage guidelines and monitoring protocols, clinicians can effectively and safely administer Magnex forte (magnesium) for various clinical indications while minimizing the risk of adverse effects.