Magaldrate

Approved Indications:

• Dyspepsia (Indigestion):
  Used for the symptomatic relief of functional dyspepsia and acid-related gastric discomfort.
• Gastritis (Acute and Chronic):
  Indicated for managing mucosal irritation and inflammation due to gastric acid overproduction.
• Gastroesophageal Reflux Disease (GERD):
  Used in mild GERD cases to neutralize gastric acid and relieve symptoms like heartburn and acid regurgitation.
• Peptic Ulcer Disease (PUD):
  Employed as adjunctive therapy for duodenal and gastric ulcers to neutralize acid and promote healing.

Clinically Accepted Off-Label Uses:

• NSAID-induced gastric irritation:
  Used alongside NSAIDs to reduce gastric mucosal irritation and dyspepsia symptoms.

Adults:

• Usual Dose: 800 mg to 1600 mg orally, 1 to 2 hours after meals and at bedtime, or as directed by a physician.
• Maximum Dose: Up to 6400 mg per day in divided doses.

Pediatrics:

• Children >12 years: Adult dose may be used under medical supervision.
• Children <12 years: Not recommended unless specifically prescribed by a physician; limited safety data available.

Elderly:

• No specific dosage adjustment required; monitor for renal function and gastrointestinal effects.

Renal Impairment:

• Caution advised. Use should be limited or avoided in patients with severe renal impairment due to the risk of aluminum and magnesium accumulation, which may lead to toxicity.

Hepatic Impairment:

• No specific dose adjustment required, but caution is recommended in advanced liver disease due to the risk of electrolyte imbalance or altered drug handling.

Route of Administration:

• Oral, available as chewable tablets or suspension.

Duration of Treatment:

• Short-term use for symptomatic relief; chronic use only under medical supervision to avoid mineral imbalances.

Magaldrate is a hydroxymagnesium aluminate complex that acts as a non-systemic, fast-acting antacid. Upon ingestion, it reacts with gastric hydrochloric acid to form aluminum chloride and magnesium chloride, leading to the neutralization of stomach acid. This process elevates gastric pH, reducing mucosal irritation and protecting the stomach lining. The aluminum component also exhibits a mild astringent and mucosal protective effect, while magnesium counters the constipating effect of aluminum, maintaining balanced gastrointestinal motility.

• Absorption: Minimal systemic absorption. Acts locally in the stomach.
• Distribution: Not significantly distributed systemically due to poor absorption.
• Metabolism: Not metabolized; works through direct chemical interaction in the gastrointestinal tract.
• Excretion:
• Unabsorbed drug: Excreted in feces.
• Absorbed aluminum/magnesium: Excreted renally.
• Onset of Action: Within approximately 30 minutes.
• Duration of Action: 2 to 3 hours, depending on gastric emptying and dosage.

• Pregnancy:
  Considered safe when used in recommended doses. Excessive or prolonged use is discouraged, especially during the third trimester, due to potential risk of mineral accumulation.
• Lactation:
  Likely safe during breastfeeding when used appropriately. Systemic absorption is minimal, and adverse effects on the breastfed infant are unlikely. Caution is advised with prolonged use.

• Primary Class: Antacid
• Subclass: Aluminum and magnesium-containing non-systemic antacid
• Generation: Non-absorbable combination agent

• Hypersensitivity to magaldrate or any of its components
• Severe renal impairment or renal failure
• Hypophosphatemia
• Gastrointestinal obstruction or severe constipation
• Alzheimer’s disease or osteomalacia (due to aluminum accumulation risk)

• Renal Impairment: Risk of accumulation of aluminum and magnesium; avoid in patients with significant renal dysfunction.
• Long-Term Use: May lead to aluminum toxicity, phosphate depletion, or altered calcium metabolism.
• Electrolyte Disturbance: Chronic use can cause hypophosphatemia or hypermagnesemia.
• Drug Absorption: May interfere with the gastrointestinal absorption of several medications (see interactions).
• Gastrointestinal Effects: Risk of diarrhea (from magnesium) or constipation (from aluminum), particularly with prolonged use.
• Pediatric Use: Use cautiously in children; long-term use may affect bone mineralization.

Common:

• Gastrointestinal:
• Constipation (aluminum-related)
• Diarrhea (magnesium-related)
• Abdominal discomfort or bloating

Less Common:

• Nausea
• Metallic taste
• Flatulence

Serious (rare):

• Metabolic:
• Hypophosphatemia
• Hypermagnesemia (especially in renal impairment)
• Neurological:
• Confusion, muscle weakness, encephalopathy (with prolonged use or renal failure)

• Tetracyclines and Fluoroquinolones: Decreased absorption due to chelation → Administer at least 2 hours apart.
• Levothyroxine: Reduced bioavailability → Separate by 4 hours.
• Iron Supplements: Decreased absorption → Avoid concurrent use.
• Digoxin and Isoniazid: May impair absorption → Separate administration recommended.
• Enteric-coated medications: Premature dissolution may occur → Avoid simultaneous intake.

Enzyme Systems Involved:

• No involvement with CYP450 enzymes. Interactions are due to direct binding in the gastrointestinal tract.

• No major recent FDA or EMA updates regarding magaldrate.
• Clinical guidelines emphasize limiting long-term use of aluminum-based antacids to prevent hypophosphatemia and aluminum-related bone disease.
• GERD and dyspepsia management protocols suggest short-term use of antacids, with transition to acid-suppressive therapy (e.g., PPIs) for persistent symptoms.

• Temperature: Store at 20°C to 25°C (68°F to 77°F); excursions permitted between 15°C and 30°C.
• Humidity and Light: Protect from moisture and direct sunlight.
• Handling Instructions:
• Store in a tightly closed container.
• Shake suspension well before use.
• Do not freeze.
• Keep out of reach of children.
• Use within the shelf life indicated on the package.