Vetdrugs 2.0Aluminum hydroxide and aluminum carbonate are alternative aluminum-containing agents used principally as oral phosphate binders and, less commonly, as antacids. The medicine name describes alternatives rather than a compulsory two-ingredient combination. Their most important small-animal role is reducing intestinal phosphorus absorption in patients with chronic kidney disease and persistent hyperphosphatemia.
Their phosphate-binding and antacid effects occur largely within the gastrointestinal lumen. They do not directly remove phosphate already present in blood, and their relatively brief neutralization of gastric acid differs from suppression of acid secretion by proton-pump inhibitors.
Group
Antacid; intestinal phosphate binder
Mechanism of Action
Aluminum binds dietary phosphate within the gastrointestinal tract to form poorly absorbed complexes. These pass in feces, decreasing the amount of phosphorus entering the circulation. A sustained reduction in absorbed phosphorus can help control hyperphosphatemia and its contribution to disturbed mineral metabolism in chronic kidney disease.
Aluminum hydroxide also reacts with gastric hydrochloric acid and raises luminal pH. Aluminum carbonate provides related acid-neutralizing and phosphate-binding effects. This chemical neutralization does not inhibit the proton pump or stop continued acid production, so the antacid action is comparatively limited in duration.
Because the principal binding target is phosphate in food, the effect depends on contact within the gut. The same adsorptive and binding properties can reduce availability of some concurrently administered medicines, while excessive phosphate binding can cause an undesirably low phosphorus concentration.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Phosphate binding - aluminum hydroxide | 10–30 mg/kg | PO | Every 8 h | Give with meals; amount is aluminum hydroxide. |
| Phosphate binding - aluminum carbonate | 10–30 mg/kg | PO | Every 8 h | Give with meals; amount is aluminum carbonate. Separate ingredient basis prevents linking to aluminum hydroxide strengths. |
| Phosphate binding - twice-daily hydroxide | 15–45 mg/kg | PO | Every 12 h | Aluminum hydroxide amount; give with meals and individualize to serum phosphate. |
| Phosphate binding - total daily hydroxide | 30–100 mg/kg | PO | Total daily amount to distribute with meals, not a specified one-time dose. A dried-powder alternative uses 30–90 mg/kg/day. | |
| Gastric ulcer adjunct - suspension | Reference only | PO | 2–10 mL PO every 2–4 hours of aluminum hydroxide or aluminum/magnesium hydroxide suspension; concentration and formulation must be identified. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Phosphate binding - aluminum hydroxide | 10–30 mg/kg | PO | Every 8 h | Give with meals; amount is aluminum hydroxide. |
| Phosphate binding - aluminum carbonate | 10–30 mg/kg | PO | Every 8 h | Give with meals; amount is aluminum carbonate. Separate ingredient basis prevents linking to aluminum hydroxide strengths. |
| Phosphate binding - twice-daily hydroxide | 15–45 mg/kg | PO | Every 12 h | Aluminum hydroxide amount; give with meals and individualize to serum phosphate. |
| Phosphate binding - total daily hydroxide | 30–90 mg/kg | PO | Total daily amount to distribute with meals, not a specified one-time dose. A dried-powder alternative uses 30–90 mg/kg/day. |
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Antacid treatment | 60 mg/kg | PO | Every 8 h | The equine entry does not identify which aluminum salt supplies the stated amount. |
| Foal gastroduodenal ulcer adjunct | Reference only | PO | 15 mL aluminum/magnesium hydroxide suspension orally four times daily in foals; active concentrations are not supplied. |
Chinchilla
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Antacid treatment | Reference only | PO | 1 mL aluminum hydroxide gel orally as needed; identify concentration before converting to an amount. |
Guinea pigs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Antacid treatment | Reference only | PO | 0.5–1 mL gel orally as needed; concentration is not specified. |
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Antacid treatment | 30 g/animal | PO | Aluminum hydroxide; no repeat interval is specified. |
Indications
- Control of persistent hyperphosphatemia in dogs and cats with chronic kidney disease when dietary phosphorus restriction alone is insufficient.
- Adjunctive reduction of intestinal phosphorus absorption during management of renal mineral-balance disorders.
- Selected antacid treatment of gastric hyperacidity or adjunctive management of gastrointestinal ulceration.
Contraindications
- Potential aluminum accumulation warrants caution during prolonged treatment.
- Use cautiously with gastric outlet obstruction because gastric emptying may slow.
Interactions
- Chelates tetracyclines and fluoroquinolones, reducing absorption; separate oral administration.
- Aluminum can reduce absorption of allopurinol, chloroquine, corticosteroids, digoxin, ethambutol, H2 blockers, iron, isoniazid, penicillamine, phenothiazines and thyroid hormones; separate oral doses by 2 hours.
Adverse effects
- Constipation.
- Hypophosphatemia during chronic treatment, particularly with phosphate restriction.
- Aluminum toxicity is documented in dogs with renal failure; watch for weakness, ataxia and microcytosis.
Toxicity
Aluminum toxicosis is a potential concern with prolonged exposure.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Aluminum hydroxide gel 64 mg/mL | Oral Liquid | 64 mg / mL | PO |
| Aluminum hydroxide 600 mg tablet | Tablet | 600 mg / tablet | PO |
| Aluminum hydroxide 500 mg capsule | Capsule | 500 mg / capsule | PO |
| Aluminum hydroxide 450 mg per 5 mL suspension | Oral Liquid | 450 mg / 5 mL | PO |
| Aluminum hydroxide 675 mg per 5 mL suspension | Oral Liquid | 675 mg / 5 mL | PO |
| Aluminum hydroxide 600 mg per 5 mL suspension | Oral Liquid | 600 mg / 5 mL | PO |
Monitoring and Administration
Give phosphate-binding treatment with meals and titrate to plasma phosphate.
Keep tightly closed, protected from light, at room temperature. Aluminum carbonate capsules described as equivalent to 500 mg aluminum hydroxide must not be treated as 500 mg carbonate.
Aluminum carbonate capsules are described by a 500 mg aluminum-hydroxide-equivalent claim, without the actual carbonate mass. Iron oxide/hydroxide complex (Lenziaren), calcium citrate and calcium carbonate are alternative binders, not interchangeable aluminum ingredients.
Tablet antacid alternatives are one-half to one tablet orally every 6 hours in dogs and one-quarter tablet every 6 hours in cats; the tablet strength is not identified, so these cannot define a milligram regimen.
Check serum phosphate after a 12-hour fast every 10–14 days initially and every 4–6 weeks once stable. Monitor neuromuscular signs, MCV and microcytosis for aluminum accumulation.