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Magnesium Hydroxide

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Magnesium Hydroxide, Milk of Magnesia

  • See Also
  1. Aluminum Hydroxide and Magnesium Hydroxide Antacid
  2. Magnesium Citrate
  3. Osmotic Laxative
  4. Laxative
  5. Constipation
  6. Functional Constipation
  7. Pediatric Constipation
  • Indications
  1. Functional Constipation
  2. Antacid
    1. See Aluminum Hydroxide and Magnesium Hydroxide Antacid
  • Contraindications
  1. Renal Failure
  2. Infants (relative contraindication)
    1. Higher risk for Hypermagnesemia
  • Mechanism
  1. Magnesium salt Osmotic Laxative
  2. Poorly absorbed, hyperosmolar agent
  • Precautions
  1. Avoid longterm use due to Electrolyte loss risk
    1. These agents are typically used once as part of a bowel regimen
  • Medications
  1. See Aluminum Hydroxide and Magnesium Hydroxide Antacid
  2. Magnesium Hydroxide Laxative concentrations
    1. Regular strength: 400 mg/5 ml
    2. Extra-Strength: 800 mg/5 ml
    3. Very High Concentration: 1200 mg/5 ml
  1. See Aluminum Hydroxide and Magnesium Hydroxide Antacid
  2. General
    1. Onset 0.5 to 6 hours
    2. Recommended as a single bedtime dose
  3. Concentration: 400 mg/5 ml (regular strength)
    1. Adult (and age >12 years)
      1. Take 30 to 60 ml (2.4 to 4.8 g) orally divided once to twice for 1 day
    2. Child (age <12 years)
      1. Age <2 years: 0.5 ml/kg/day divided once to twice for 1 day (caution, risk of Hypermagnesemia)
      2. Age 2 to 5 years: 5 to 15 ml (0.4 to 1.2 g) divided once to twice for 1 day
      3. Age 6 to 12 years: 15 to 30 ml (1.2 to 2.4 g) divided once to twice for 1 day
  4. Concentration 800 mg/5 ml (extra strength)
    1. Adult: 15 to 30 ml orally divided once to twice for 1 day
  5. Concentration 1200 mg/5 ml (very high concentration)
    1. Adult: 10 to 20 ml orally divided once to twice for 1 day
  • Pharmacokinetics
  1. Rapid onset within 3 hours
  • Adverse Effects
  1. Abdominal cramping (higher doses)
  2. Hypermagnesemia (in patients with Renal Failure, infants)
  • Safety
  1. Pregnancy Category B
  2. Unknown Safety in Lactation
  • Resources
  1. Magnesium Hydroxide (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2de868a0-c652-473c-8b61-636083b7f757
  • References
  1. (2023) Management of Constipation, Presc Lett, #390108
  2. Hamilton (2020) Tarascon Pocket Pharmacopoeia