Aluminum Hydroxide
Aluminum hydroxide is an orally administered compound primarily used in veterinary medicine as an **enteric phosphate binder** to manage hyperphosphatemia in patients with **chronic kidney disease (CKD)**. * It is also utilized as a **gastric antacid** to treat or prevent gastrointestinal ulcers. * > **Clinical Pearl:** While human liquid antacids (like mint-flavored suspensions) are available over-the-counter, they are often highly unpalatable to dogs and cats. Compounded dried powders are virtually tasteless and much easier to administer when mixed with canned food.
Mechanism: * **Phosphate Binding:** In the gastrointestinal tract, **aluminum** binds to dietary **phosphate** โ forms insoluble **aluminum phosphate** โ excreted in the feces. This prevents the systemic absorption of phosphorus, thereby lowering serum phosphorus levels. * **Antacid:** Neutralizes gastric hydrochloric acid โ increases gastric pH โ reduces pepsin activity, providing a protective effect on the gastric mucosa.
Dosing by species
- Hyperphosphatemia ยท Initially at 30-90 mg/kg per day ยท PO ยท divided with meals ยท Dosage must be individualized. Capsules or suspension are preferred as they are more easily mixed with food and dispersed throughout ingesta.
- Hyperphosphatemia ยท 15-45 mg/kg ยท PO ยท q12h
- As an antacid ยท ยผ tablet ยท PO ยท q6h ยท Aluminum hydroxide tablets
- As an antacid ยท 30 grams/animal ยท PO ยท as needed
- Adjunctive gastroduodenal ulcer therapy in foals ยท 15 mL (total dose) ยท PO ยท 4 times a day ยท Aluminum/magnesium hydroxide suspension
- General ยท 1 mL/animal ยท PO ยท as needed ยท Chinchillas; Aluminum hydroxide gel
- General ยท 0.5-1 mL/animal ยท PO ยท as needed ยท Guinea pigs
- Hyperphosphatemia ยท 30-100 mg/kg/day ยท PO ยท with meals
- Hyperphosphatemia ยท 30-90 mg/kg/day ยท PO ยท prior to meals ยท Aluminum hydroxide gel, dried powder. The dried powder is virtually tasteless and accepted readily by most cats when mixed with canned food.
Routes of administration
Contraindications
- Use with caution in patients with delayed gastric emptying or severe constipation
- Use with caution in patients with severe renal failure due to risk of aluminum accumulation
Adverse effects
- Constipation
- Aluminum toxicity (neuromuscular weakness, microcytosis) with chronic use or severe renal impairment
- Hypophosphatemia (if over-supplemented)
Drug interactions
- Isoniazid ยท Decreased absorption; separate oral doses by two hours
- Penicillamine ยท Decreased absorption; separate oral doses by two hours
- Phenothiazines ยท Decreased absorption; separate oral doses by two hours
- Tetracyclines ยท Decreased absorption; separate oral doses by two hours
- Thyroid Hormones ยท Decreased absorption; separate oral doses by two hours
Monitoring
- Serum phosphorus (after a 12-hour fast), initially at 10-14 day intervals; once 'stable', at 4-6 week intervals
- Neuromuscular effects (signs of aluminum toxicity)
- Progressive decreases in mean cell volume (MCV) and microcytosis
Overdose
Chronic overdosage or accumulation in patients with severe renal failure can lead to **aluminum toxicity**. * Signs of toxicity include neuromuscular effects (weakness, stumbling, difficulty walking) and hematological changes (progressive decreases in mean cell volume [MCV] and microcytosis).
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.