Usage
- Magnesium carbonate is prescribed for the relief of symptoms associated with indigestion, heartburn, and dyspepsia (upset stomach). It can also be used as a saline laxative for occasional constipation and as a magnesium supplement for treating or preventing magnesium deficiency.
- Pharmacological Classification: Antacid, Laxative, Mineral Supplement.
- Mechanism of Action: Magnesium carbonate neutralizes stomach acid by reacting with hydrochloric acid (HCl) to produce magnesium chloride, carbon dioxide, and water. This chemical reaction reduces the acidity in the stomach, relieving heartburn and indigestion symptoms. When used as a laxative, magnesium carbonate draws water into the intestines, softening stool and promoting bowel movements.
Alternate Names
- Carbonate of magnesia
- Magnesia alba
- Heavy magnesium carbonate
- Light magnesium carbonate
Some brand names containing magnesium carbonate include:
- Gaviscon (in combination with other antacids)
- Phillips’ Milk of Magnesia (contains magnesium hydroxide, which converts to magnesium carbonate in the stomach)
How It Works
- Pharmacodynamics: Magnesium carbonate increases stomach pH by neutralizing gastric acid. As a laxative, it increases osmotic pressure in the intestinal lumen, drawing water in and stimulating peristalsis.
- Pharmacokinetics: Magnesium carbonate is poorly absorbed from the gastrointestinal tract. The small amount absorbed is primarily excreted by the kidneys. Unabsorbed magnesium is eliminated in the feces. The onset of action as an antacid is rapid (within 15-30 minutes), while the laxative effect can take 30 minutes to 6 hours.
- Mode of Action: Neutralization of HCl in the stomach lumen.
- Receptor Binding, Enzyme Inhibition, or Neurotransmitter Modulation: None known.
- Elimination Pathways: Primarily fecal excretion of unabsorbed magnesium; renal excretion of the small amount that is absorbed.
Dosage
Standard Dosage
Adults:
- Antacid: 500-1000 mg orally every 3 to 4 hours as needed, preferably between meals and at bedtime. Maximum dose: 4000 mg/day. Duration of therapy: Up to 2 weeks.
- Laxative: 2-5 grams orally with a full glass of water.
- Supplement: Recommended Dietary Allowance (RDA): Males 400-420 mg/day; Females 310-320 mg/day. Tolerable Upper Intake Level (UL) from supplements and medication: 350 mg/day.
Children:
- Antacid (6 to 12 years): 250-500 mg orally every 3 to 4 hours as needed. Maximum dose: 2000 mg/day. Duration of therapy: Up to 2 weeks.
- Laxative and Supplement: Consult a pediatrician for appropriate dosing based on age and weight.
Special Cases:
- Elderly Patients: Use with caution due to potential for decreased renal function. Monitor magnesium levels.
- Patients with Renal Impairment: Use with caution. Hypermagnesemia risk is increased. Dose adjustment may be necessary. Monitor magnesium levels closely.
- Patients with Hepatic Dysfunction: Data on dose adjustments are limited.
- Patients with Comorbid Conditions: Use with caution in patients with diabetes, heart block, or bleeding disorders.
Clinical Use Cases:
Magnesium carbonate is generally not recommended for clinical use cases like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations. Intravenous magnesium sulfate is typically used in these settings.
Dosage Adjustments:
Dose adjustments may be required based on renal function, concomitant medications, and patient response.
Side Effects
Common Side Effects:
- Diarrhea
- Stomach upset
- Nausea
- Gas
Rare but Serious Side Effects:
- Allergic reactions (rash, itching, hives, swelling, difficulty breathing)
- Hypermagnesemia (symptoms can include muscle weakness, low blood pressure, confusion, slowed breathing, and cardiac arrest)
Long-Term Effects:
Long-term use of high doses can cause hypermagnesemia.
Adverse Drug Reactions (ADR):
Contraindications
- Renal failure
- Bowel obstruction
- Hypersensitivity to magnesium carbonate
Drug Interactions
Magnesium carbonate can interact with several medications, including:
- Tetracyclines
- Bisphosphonates
- Digoxin
- Quinolone antibiotics
- Levothyroxine
- Certain antihypertensives
It’s crucial to separate the administration of magnesium carbonate from these medications by at least 2-3 hours. Consult a drug interaction checker for a complete list.
Pregnancy and Breastfeeding
- Pregnancy: Generally considered safe for use during pregnancy when taken in recommended doses. However, consult a doctor before use.
- Breastfeeding: Limited information suggests it is likely safe during breastfeeding, but consult a doctor before use. Magnesium is a natural component of breast milk.
Drug Profile Summary
- Mechanism of Action: Neutralizes stomach acid, osmotic laxative.
- Side Effects: Diarrhea, stomach upset, nausea, allergic reactions, hypermagnesemia.
- Contraindications: Renal failure, bowel obstruction, hypersensitivity.
- Drug Interactions: Tetracyclines, bisphosphonates, digoxin, quinolones.
- Pregnancy & Breastfeeding: Generally safe in recommended dosages; consult a physician.
- Dosage: See detailed dosage section above.
- Monitoring Parameters: Serum magnesium levels (especially in patients with renal impairment).
Popular Combinations:
Often combined with aluminum hydroxide and/or simethicone in antacid formulations.
Precautions
- General Precautions: Evaluate renal function before use, especially in elderly patients. Avoid long-term use of high doses.
- Specific Populations: See dosage adjustments above.
- Lifestyle Considerations: None specific.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Magnesium Carbonate?
A: See detailed dosage section above.
Q2: How does Magnesium Carbonate work as an antacid?
A: It neutralizes stomach acid by reacting with hydrochloric acid.
Q3: Can I take Magnesium Carbonate during pregnancy?
A: Generally considered safe in recommended doses, but consult with your physician.
Q4: What are the potential side effects of Magnesium Carbonate?
A: Common side effects include diarrhea, stomach upset, and nausea. Rarely, allergic reactions or hypermagnesemia can occur.
Q5: How should I take Magnesium Carbonate for constipation?
A: 2-5 grams orally with a full glass of water.
Q6: Does Magnesium Carbonate interact with other medications?
A: Yes, it can interact with certain antibiotics, bisphosphonates, and other medications. Consult a doctor or pharmacist about potential interactions.
Q7: What is the difference between Magnesium Carbonate and Magnesium Citrate?
A: While both are magnesium salts, they have different properties and uses. Magnesium citrate is primarily used as a laxative, while magnesium carbonate is used as both an antacid and laxative.
Q8: Can Magnesium Carbonate be used to treat magnesium deficiency?
A: Yes, it can be used as a magnesium supplement but other forms of magnesium may be better absorbed.
Q9: What should I do if I experience side effects while taking Magnesium Carbonate?
A: Consult with your physician if you experience any bothersome or persistent side effects.
Q10: Is Magnesium Carbonate safe for long-term use?
A: Long-term use of high doses can lead to hypermagnesemia. It is important to follow recommended dosages and consult with a healthcare professional for long-term use.
