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# Aluminium Hydroxide
## Overview
Aluminium hydroxide is an inorganic salt used primarily as an antacid. It acts by neutralizing gastric acid to form aluminium chloride and water. It is poorly absorbed from the gastrointestinal tract; however, small amounts are systemically absorbed and excreted by the kidneys.
## Primary Indications
* Relief of heartburn, acid indigestion, and sour stomach.
* Hyperphosphatemia (in patients with chronic kidney disease).
* Adjunct therapy in peptic ulcer disease (less common due to modern PPI/H2RA availability).
## Adult Dosing
* **Antacid:** 500 mg to 1,500 mg orally as needed, taken 30–60 minutes after meals and at bedtime. Maximum daily dose generally advised at 4–6 g/day depending on the specific formulation; adhere to product labeling.
* **Hyperphosphatemia:** Initially 500 mg to 1,800 mg taken daily in divided doses with meals. Titrate based on serum phosphate levels.
## Pediatric Dosing
* **Antacid:** Safety and efficacy are not well-established for routine pediatric use. Pediatric dosing is often institution-specific; generally, 5–15 mL (depending on concentration) via mouth as needed. Consult weight-based institutional guidelines.
* **Hyperphosphatemia:** 50–150 mg/kg/day in divided doses with meals. Titrate to effect.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Aluminium accumulates in patients with renal failure. Long-term use in patients with creatinine clearance <30 mL/min is generally contraindicated or requires strict monitoring to prevent aluminium encephalopathy and osteomalacia.
## Contraindications
* Hypersensitivity to aluminium products.
* Severe abdominal pain of unknown origin.
* Patients with bowel obstruction (due to constipation risk).
## Adverse Effects
* **Common:** Constipation (very frequent), which may lead to impaction.
* **Serious:** Hypophosphatemia (due to binding of dietary phosphate in the gut), aluminium toxicity (manifesting as encephalopathy, seizures, or bone pain in chronic renal impairment).
## Key Drug Interactions
* **Absorption Inhibition:** Aluminium hydroxide significantly decreases the absorption of tetracyclines, fluoroquinolones (e.g., ciprofloxacin, levofloxacin), bisphosphonates, levothyroxine, and iron salts.
* **Timing:** Administer these medications at least 2 hours before or 4–6 hours after aluminium hydroxide to avoid binding interactions.
* **Urinary pH:** May increase urinary pH, potentially affecting the excretion of other drugs.
## Monitoring
* **Phosphorus Levels:** Long-term use requires monitoring for hypophosphatemia.
* **Renal Function:** Monitor serum creatinine/BUN in patients on chronic therapy.
* **Stool Pattern:** Monitor for development of severe constipation.
## Clinical Pearls
* Aluminium hydroxide is constipating; it is often combined with magnesium hydroxide (which causes diarrhea) in commercial antacid suspensions to balance bowel function and maintain efficacy.
* Advise patients that antacids only provide symptomatic relief and do not treat the underlying cause of ulceration or GERD.
* Encourage adequate hydration to minimize the risk of constipation.
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**Disclaimer:** This information is for educational purposes only. Direct clinical decisions must be based on institutional protocols, updated clinical guidelines, and the patient’s specific medical history. Always consult the current primary literature or a clinical pharmacist before prescribing or administering medication.
