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Related to Alu-cap: Aludrox, AlternaGEL

aluminum hydroxide

AlternaGEL, Alu-Cap, Alu-Tab

Pharmacologic class: Inorganic salt

Therapeutic class: Antacid

Pregnancy risk category NR


Dissolves in acidic gastric secretions, releasing anions that partially neutralize gastric hydrochloric acid. Also elevates gastric pH, inhibiting the action of pepsin (an effect important in peptic ulcer disease).


Capsules: 400 mg, 475 mg, 500 mg

Oral suspension: 320 mg/5 ml, 450 mg/5 ml, 600 mg/5 ml, 675 mg/5 ml

Tablets: 300 mg, 500 mg, 600 mg

Indications and dosages


Adults: 500 to 1,500 mg (tablet or capsule) P.O. 1 hour after meals and at bedtime; or 5 to 30 ml (oral suspension) between meals and at bedtime, as needed or directed

Off-label uses

• Bleeding from stress ulcers

• Gastroesophageal reflux disease


• Signs or symptoms of appendicitis or inflamed bowel


Use cautiously in:

• gastric outlet obstruction, hypercalcemia, hypophosphatemia, massive upper GI hemorrhage

• patients using other aluminum products concurrently

• patients on dialysis

• pregnant or breastfeeding patients.


• Administer with water or fruit juice.

• Give 1 hour after meals and at bedtime.

• In reflux esophagitis, administer 20 to 40 minutes after meals and at bedtime.

• Don't give within 1 to 2 hours of antibiotics, histamine2 (H2) blockers, iron preparations, corticosteroids, or enteric-coated drugs.

• Provide care as appropriate if patient becomes constipated.

Adverse reactions

CNS: malaise (with prolonged use), neurotoxicity, encephalopathy

GI: constipation, anorexia (with prolonged use), intestinal obstruction

Metabolic: hypophosphatemia (with prolonged use)

Musculoskeletal: osteomalacia and chronic phosphate deficiency with bone pain, malaise, muscle weakness (with prolonged use)

Other: aluminum toxicity


Drug-drug. Allopurinol, anti-infectives (including quinolones, tetracyclines), corticosteroids, diflunisal, digoxin, ethambutol, H2 blockers, hydantoins, iron salts, isoniazid, penicillamine, phenothiazines, salicylates, thyroid hormone, ticlopidine: decreased effects of these drugs

Enteric-coated drugs: premature release of these drugs in stomach

Drug-diagnostic tests. Gastrin: increased level

Phosphate: decreased level

Some imaging studies: test interference

Drug-food. Milk, other foods high in vitamin D: milk-alkali syndrome (nausea, vomiting, distaste for food, headache, confusion, hypercalcemia, hypercalciuria)

Patient monitoring

• Monitor long-term use of high doses if patient is on sodium-restricted diet. (Drug contains sodium.)

• Assess for GI bleeding.

• Watch for constipation.

• With long-term use, monitor blood phosphate level and assess for signs and symptoms of hypophosphatemia (anorexia, malaise, muscle weakness). Also monitor bone density.

Patient teaching

• Tell patient to take drug 1 hour after meals and at bedtime.

• Caution patient not to take drug within 1 to 2 hours of anti-infectives, H2 blockers, iron, corticosteroids, or enteric-coated drugs.

• Advise patient to take drug with water or fruit juice.

• Instruct patient to report signs and symptoms of GI bleeding and hypo-phosphatemia (appetite loss, malaise, muscle weakness).

• Recommend increased fiber and fluid intake and regular physical activity to help ease constipation.

• Inform patient that drug contains sodium, so he should discuss drug therapy with health care providers if he's later told to consume a low-sodium diet.

• Advise patient that he'll need to undergo periodic blood testing and bone mineral density tests if he's receiving long-term therapy.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and foods mentioned above.

McGraw-Hill Nurse's Drug Handbook, 7th Ed. Copyright © 2013 by The McGraw-Hill Companies, Inc. All rights reserved

aluminum hydroxide



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Therapeutic: antiulcer agents
Pharmacologic: antacids
Pregnancy Category: UK


Lowering of phosphate levels in patients with chronic renal failure.Adjunctive therapy in the treatment of peptic, duodenal, and gastric ulcers.Hyperacidity, indigestion, reflux esophagitis.


Binds phosphate in the GI tract.
Neutralizes gastric acid and inactivates pepsin.

Therapeutic effects

Lowering of serum phosphate levels.
Healing of ulcers and decreased pain associated with ulcers or gastric hyperacidity.
Constipation limits use alone in the treatment of ulcer disease.
Frequently found in combination with magnesium-containing compounds.


Absorption: With chronic use, small amounts of aluminum are systemically absorbed.
Distribution: If absorbed, aluminum distributes widely, crosses the placenta, and enters breast milk. Concentrates in the CNS with chronic use.
Metabolism and Excretion: Mostly excreted in feces. Small amounts absorbed are excreted by the kidneys.
Half-life: Unknown.

Time/action profile

PO‡15–30 min30 min30 min–3 hr
†Hypophosphatemic effect‡Antacid effect


Contraindicated in: Severe abdominal pain of unknown cause.
Use Cautiously in: Hypercalcemia;Hypophosphatemia; Obstetric: Generally considered safe; chronic high-dose therapy should be avoided.

Adverse Reactions/Side Effects


  • constipation (most frequent)

Fluid and Electrolyte

  • hypophosphatemia


Drug-Drug interaction

Absorption of tetracyclines, chlorpromazine, iron salts, isoniazid, digoxin, or fluoroquinolones may be decreased.Salicylate blood levels may be decreased.Quinidine, mexiletine, and amphetamine levels may be increased if enough antacid is ingested such that urine pH is increased.



Oral (Adults) 1.9–4.8 g (30–40 mL of regular suspension or 15–20 mL of concentrated suspension) 3–4 times daily.
Oral (Children) 50–150 mg/kg/24 hr in 4–6 divided doses; titrate to normal serum phosphate levels.


Oral (Adults) 500–1500 mg (5–30 mL) 3–6 times daily.

Availability (generic available)

Capsules: 475 mgOTC, 500 mgOTC
Tablets: 300 mgOTC, 500 mgOTC, 600 mgOTC
Suspension: 320 mg/5 mLOTC, 450 mg/5 mLOTC, 600 mg/5 mLOTC, 675 mg/5 mLOTC
In combination with: magnesium carbonate, calcium carbonate, simethicone, and mineral oil. See combination drugs.

Nursing implications

Nursing assessment

  • Assess location, duration, character, and precipitating factors of gastric pain.
  • Lab Test Considerations: Monitor serum phosphate and calcium levels periodically during chronic use of aluminum hydroxide.
    • May cause increased serum gastrin and decreased serum phosphate concentrations.
    • In treatment of severe ulcer disease, guaiac stools, and emesis, monitor pH of gastric secretions.

Potential Nursing Diagnoses

Acute pain (Indications)
Constipation (Side Effects)


  • Antacids cause premature dissolution and absorption of enteric-coated tablets and may interfere with absorption of other oral medications. Separate administration of aluminum hydroxide and oral medications by at least 1–2 hr.
    • Tablets must be chewed thoroughly before swallowing to prevent their entering small intestine in undissolved form. Follow with a glass of water.
    • Shake liquid preparations well before pouring. Follow administration with water to ensure passage into stomach.
    • Liquid dosage forms are considered more effective than tablets.
  • Hypophosphatemic: For phosphate lowering, follow dose with full glass of water or fruit juice.
  • Antacid: May be given in conjunction with magnesium-containing antacids to minimize constipation, except in patients with renal failure. Administer 1 and 3 hr after meals and at bedtime for maximum antacid effect.
    • For treatment of peptic ulcer, aluminum hydroxide may be administered every 1–2 hr while the patient is awake or diluted with 2–3 parts water and administered intragastrically every 30 min for 12 or more hr per day. Physician may order NG tube clamped after administration.
    • For reflux esophagitis, administer 15 mL 20–40 min after meals and at bedtime.

Patient/Family Teaching

  • Instruct patient to take aluminum hydroxide exactly as directed. If on a regular dosing schedule and a dose is missed, take as soon as remembered if not almost time for next dose; do not double doses.
    • Advise patient not to take aluminum hydroxide within 1–2 hr of other medications without consulting health care professional.
    • Advise patients to check label for sodium content. Patients with HF or hypertension, or those on sodium restriction, should use low-sodium preparations.
    • Inform patients of potential for constipation from aluminum hydroxide.
  • Hypophosphatemia: Patients taking aluminum hydroxide for hyperphosphatemia should be taught the importance of a low-phosphate diet.
  • Antacid: Caution patient to consult health care professional before taking antacids for more than 2 wk if problem is recurring, if taking other medications, if relief is not obtained, or if symptoms of gastric bleeding (black tarry stools, coffee-ground emesis) occur.

Evaluation/Desired Outcomes

  • Decrease in serum phosphate levels.
  • Decrease in GI pain and irritation.
    • Increase in the pH of gastric secretions. In treatment of peptic ulcer, antacid therapy should be continued for at least 4–6 wk after symptoms have disappeared because there is no correlation between disappearance of symptoms and healing of ulcers.
Drug Guide, © 2015 Farlex and Partners


Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005