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# Aluminium Hydroxide
## Overview
Aluminium hydroxide is a nonsystemic antacid that neutralizes gastric hydrochloric acid to form aluminium chloride and water. It is frequently formulated with magnesium salts to counteract the constipating effects of aluminium.
## Primary Indications
* Management of heartburn, acid indigestion, and sour stomach.
* Hyperphosphatemia (as a phosphate binder in chronic kidney disease).
* Prophylaxis of stress-induced gastric ulcers (less common now due to PPI/H2RA dominance).
## Adult Dosing
* **Antacid (Liquid/Tablet):** 500–1500 mg orally between meals and at bedtime, or as needed. Do not exceed 8–12 grams daily without medical supervision.
* **Phosphate Binder:** 500–2000 mg taken with meals three times daily. Titrate based on serum phosphate levels.
## Pediatric Dosing
* **Antacid:** Safety and efficacy are not well-established for routine pediatric use. If used, consult clinical guidelines; typically 5–15 mL (standard suspension strength) given 1–3 hours after meals and at bedtime.
* **Phosphate Binder:** 50–150 mg/kg/day divided into 4–6 doses, administered with meals. Titrate to effect. *Caution: Avoid chronic use in neonates and infants due to risk of aluminium toxicity.*
## Dose Adjustments
* **Renal Impairment:** Use with extreme caution in patients with renal failure. Aluminium accumulation can lead to osteomalacia, encephalopathy, and microcytic anemia. Phosphate-binding doses must be closely monitored by a nephrologist.
## Contraindications
* Hypersensitivity to aluminium products.
* Severe abdominal pain of unknown origin.
* Prolonged, high-dose use in patients with severe renal impairment (due to neurotoxicity risk).
## Adverse Effects
* **Gastrointestinal:** Dose-dependent constipation (common), intestinal obstruction (in high doses), hypophosphatemia.
* **Metabolic:** Aluminium toxicity (in renal failure), osteomalacia (chronic high doses).
## Key Drug Interactions
* **Absorption Inhibition:** Aluminium hydroxide chelates with many drugs, significantly reducing their bioavailability. Separate by at least 2 hours from: tetracyclines, fluoroquinolones, iron supplements, bisphosphonates, levothyroxine, and ketoconazole.
* **Urine pH:** May increase urine pH, potentially decreasing the excretion of basic drugs (e.g., amphetamines, quinidine).
## Monitoring
* **Phosphate Binder Use:** Serum phosphate levels (goal usually 3.5–5.5 mg/dL).
* **Long-term Use:** Monitor for constipation and signs of aluminium toxicity (mental status changes). Ensure adequate fluid intake.
## Clinical Pearls
* **Formulation:** Antacid efficacy varies by local formulation; always check the concentration (e.g., 320 mg/5 mL vs. 600 mg/5 mL).
* **Chelation:** Always emphasize the "2-hour gap" rule to patients taking other medications.
* **Magnesium Combinations:** If the patient experiences significant constipation, discuss switching to an aluminium/magnesium hydroxide combination product, provided renal function is normal.
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*Disclaimer: This information is for educational purposes and does not replace professional medical judgment. Always verify dosages, contraindications, and drug-drug interactions using current prescribing information (e.g., package inserts, Lexicomp, or UpToDate) and local institutional guidelines before prescribing or administering medication.*
