Aluminum Hydroxide

Aluminum Hydroxide is an inorganic salt used primarily as an antacid to relieve heartburn and as a phosphate binder in patients with chronic kidney disease. It belongs to the antacid and phosphate binder drug classes.

Dosage for Aluminum Hydroxide must be individualized based on the condition being treated and the patient's response.

• For Antacid Use (Heartburn/Indigestion): The typical adult dose ranges from 500 mg to 1,500 mg taken orally. This is usually administered 1 to 3 hours after meals and at bedtime. Healthcare providers generally recommend not exceeding 6,000 mg in a 24-hour period unless specifically directed.
• For Hyperphosphatemia (Phosphate Binding): The starting dose is often 300 mg to 600 mg taken with each meal. This dose may be titrated (adjusted) by a nephrologist based on serum phosphorus levels. In some clinical settings, doses may reach up to 2,000 mg per meal, though this increases the risk of aluminum toxicity.

Aluminum Hydroxide should be used with extreme caution in children.

• Children under 6 years: Use is generally not recommended unless specifically directed by a pediatrician, as young children are at higher risk for electrolyte imbalances.
• Children 6 to 12 years: For antacid use, the dose is typically 250 mg to 500 mg, not to exceed 2,000 mg per day.
• Safety Note: Pediatric use for phosphate binding is rare and must be managed by a pediatric nephrologist due to the risks of aluminum accumulation affecting bone growth and neurological development.

Renal Impairment

In patients with significant renal impairment (Stage 4 or 5 CKD), Aluminum Hydroxide must be used with extreme caution. While it is used to treat a complication of kidney disease, the kidneys are also the only way to remove absorbed aluminum. Prolonged use in these patients can lead to 'dialysis encephalopathy' or 'dialysis dementia.' Doses should be kept to the minimum effective amount for the shortest duration possible.

Hepatic Impairment

No specific dose adjustments are typically required for patients with liver disease, as the drug is not metabolized by the liver. However, patients with cirrhosis and associated fluid retention should monitor their intake if using combination products that contain high sodium levels.

Elderly Patients

Older adults are more prone to constipation and may have undiagnosed age-related declines in kidney function. Lower starting doses and increased fluid intake are often recommended to prevent bowel impaction.

• Liquid Suspension: Always shake the bottle well before each use. Use a calibrated measuring device (not a household spoon) to ensure the correct dose.
• Chewable Tablets: These must be chewed completely before swallowing. Do not swallow them whole, as the tablet will not dissolve properly in the stomach to neutralize acid.
• Timing: For acid reflux, take the medication roughly 1 hour after eating. For phosphate binding, the medication must be taken with meals or snacks to interact with dietary phosphorus.
• Water Intake: Follow each dose with a full glass (8 oz) of water to help the medication reach the stomach and to minimize the risk of constipation.
• Storage: Store at room temperature (68°F to 77°F). Do not freeze liquid formulations, as this can change the consistency and effectiveness of the suspension.

If you miss a dose, take it as soon as you remember. If it is almost time for your next scheduled dose, skip the missed dose and return to your regular schedule. Do not double the dose to catch up. For those using it as a phosphate binder, if you finish a meal and forget the dose, take it immediately; however, if several hours have passed since the meal, the dose may no longer be effective for that specific meal.

Signs of an acute overdose may include severe constipation, stomach cramps, or a complete bowel obstruction. Chronic overdose (taking too much over a long period) can lead to aluminum toxicity, characterized by confusion, muscle weakness, and bone pain. In the event of a suspected overdose, contact a Poison Control Center or seek emergency medical care immediately.

> Important: Follow your healthcare provider's dosing instructions. Do not adjust your dose or use the medication for more than two weeks without medical guidance.

The most frequent side effect associated with Aluminum Hydroxide is constipation. Because aluminum salts have an astringent effect on the intestinal mucosa and slow down gastric emptying, the stool can become hard and difficult to pass. This effect is dose-dependent and is the primary reason many manufacturers combine Aluminum Hydroxide with Magnesium Hydroxide (which has a laxative effect). Patients may also experience a 'chalky' or unpleasant taste in the mouth immediately after administration, particularly with liquid or chewable forms.

• Nausea and Vomiting: Some patients may find the texture or taste of the medication induces mild nausea.
• Stomach Cramps: As the medication slows intestinal motility, mild cramping or bloating may occur.
• Hypophosphatemia (Low Phosphate)

Aluminum Hydroxide is generally safe for short-term use in healthy individuals, but it is not a benign substance. The most critical safety consideration is the duration of use. Patients should not use this medication for more than 2 weeks for acid symptoms without consulting a physician. Persistent heartburn can be a sign of more serious conditions, such as a peptic ulcer or esophageal cancer, which require a different diagnostic and treatment approach.

No FDA black box warnings for Aluminum Hydroxide.

• Renal Insufficiency: This is the most significant precaution. If your kidneys are not working at 100% capacity, aluminum can build up in your body to toxic levels. Always inform your doctor of your kidney function status before starting this medication.

There are few absolute contraindications, but the use of Aluminum Hydroxide with Citrate salts (found in some calcium supplements like calcium citrate or in 'Alka-Seltzer' products) is highly discouraged. Citrate significantly increases the intestinal absorption of aluminum (by up to 50 times), which can lead to rapid-onset aluminum toxicity, especially in patients with kidney disease.

Aluminum Hydroxide can significantly decrease the absorption of many important medications by binding to them in the gut (chelation) or by changing the stomach's pH.

• Quinolone Antibiotics (e.g., Ciprofloxacin, Levofloxacin): Aluminum can reduce the absorption of these drugs by up to 90%, potentially causing treatment failure for serious infections.
• Tetracycline Antibiotics (e.g., Doxycycline): Similar to quinolones, these should be taken at least 2 hours before or 6 hours after Aluminum Hydroxide.

Aluminum Hydroxide must NEVER be used in the following circumstances:

• Known Hypersensitivity: If you have had a previous allergic reaction to aluminum salts.
• Severe Unresolved Constipation: Using this medication in a patient with an existing bowel impaction can lead to intestinal perforation or severe obstruction.
• Hypophosphatemia: Because the drug's primary non-antacid function is to remove phosphate, using it in someone who already has low phosphate is clinically dangerous and can lead to respiratory failure or muscle breakdown (rhabdomyolysis).

Conditions requiring careful risk-benefit analysis by a physician include:

Aluminum Hydroxide is generally considered safe for short-term use during pregnancy when taken at recommended OTC doses. It is often a second-line choice after calcium-based antacids for pregnancy-related heartburn. According to the FDA, it is not formally categorized under the old A-X system for most OTC labels, but clinical data suggests no increased risk of birth defects. However, long-term use or high doses should be avoided to prevent mineral imbalances in the mother and fetus. Always consult an OB/GYN before use.

Small amounts of aluminum may be excreted into breast milk, but because the mother absorbs so little of the drug, the amount passed to the infant is considered clinically insignificant. It is generally regarded as compatible with breastfeeding. However, nursing mothers should avoid taking it with citrate-containing products to prevent increased absorption.

As noted in the dosage section, use in children under 6 is generally discouraged. In older children, it should only be used for short-term relief. Chronic use in children is particularly dangerous because their developing bones and brains are more sensitive to the toxic effects of aluminum and the growth-stunting effects of phosphate depletion.

Aluminum Hydroxide is an inorganic salt with the chemical formula Al(OH)3. Its primary pharmacologic effect is the chemical neutralization of hydrochloric acid (HCl) in the gastric lumen. The reaction is as follows:

Al(OH)3 + 3HCl → AlCl3 + 3H2O

This reaction results in the formation of aluminum chloride and water, effectively raising the pH of the stomach. By reducing the acidity, it also decreases the activity of pepsin. In the intestine, the aluminum chloride reacts with dietary phosphate to form insoluble aluminum phosphate (AlPO4), which is then excreted.

The onset of acid neutralization is relatively slow compared to sodium bicarbonate but provides a longer duration of effect. The buffering capacity of Aluminum Hydroxide is high, but it does not typically raise the gastric pH above 4 or 5, which is beneficial as it avoids the 'acid rebound' associated with making the stomach too alkaline. The duration of action is approximately 20-60 minutes if taken on an empty stomach and up to 3 hours if taken after a meal.