Aluminum Hydroxide

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): Because the drug binds phosphate so effectively, it can actually lower phosphate levels too much in patients with normal kidney function. Symptoms include loss of appetite and general malaise (feeling unwell).

• Hypomagnesemia: In rare cases, prolonged use can interfere with the absorption of other minerals.
• Milk-Alkali Syndrome: While more common with calcium carbonate, excessive use of antacids can lead to high blood calcium levels and kidney damage.
• Bowel Obstruction (Ileus): In patients with pre-existing motility issues or those taking very high doses, the constipation can progress to a complete blockage of the intestines.

> Warning: Stop taking Aluminum Hydroxide and call your doctor immediately if you experience any of the following serious symptoms:

• Severe Abdominal Pain: This could indicate a bowel obstruction or perforation.
• Mental Status Changes: Confusion, memory loss, or extreme irritability, which may be early signs of aluminum-induced neurotoxicity.
• Muscle Weakness or Bone Pain: This may indicate 'osteomalacia' (softening of the bones) due to chronic phosphate depletion.
• Black, Tarry Stools: While Aluminum Hydroxide usually makes stools lighter in color, black stools could indicate a gastrointestinal bleed that the antacid is masking.
• Signs of an Allergic Reaction: Rash, itching, swelling of the face/tongue/throat, or severe dizziness and trouble breathing.

Prolonged use of Aluminum Hydroxide (months to years) carries significant risks, particularly for the skeletal and neurological systems:

• Aluminum Toxicity: Over time, aluminum can deposit in the brain, leading to a progressive form of dementia. This was historically known as 'dialysis dementia' in the 1970s and 80s.
• Osteomalacia and Fractures: By chronically depleting phosphate, the body cannot properly mineralize bone matrix. This leads to brittle bones that are highly susceptible to fractures, even with minor trauma.
• Microcytic Anemia: Excess aluminum can interfere with iron metabolism, leading to a specific type of anemia that does not respond to iron supplements.
• Proximal Myopathy: Weakness in the large muscles of the legs and arms, making it difficult to stand up from a chair or climb stairs.

No FDA black box warnings currently exist for Aluminum Hydroxide. However, the clinical community maintains a high level of vigilance regarding its use in patients with renal failure due to the well-documented risk of systemic aluminum accumulation.

Report any unusual symptoms to your healthcare provider. Monitoring of blood mineral levels (calcium, phosphate, aluminum) is often required for long-term users.

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.
• Gastrointestinal Obstruction: Patients with known bowel obstructions or severe constipation should avoid Aluminum Hydroxide, as it will likely worsen the condition.
• Hypophosphatemia: If you already have low phosphate levels, this medication can drop them to dangerously low levels, affecting heart and muscle function.
• Alzheimer’s Disease and Dementia: There has been historical debate regarding aluminum and Alzheimer’s. While a direct causative link remains unproven, many clinicians advise caution in patients with existing cognitive impairment due to the known neurotoxic potential of absorbed aluminum.
• Allergic Reactions: Though rare, hypersensitivity to aluminum salts can occur. Symptoms include hives and respiratory distress.

For patients taking Aluminum Hydroxide long-term, especially for phosphate binding, the following laboratory tests are typically required every 1 to 3 months:

• Serum Phosphorus: To ensure the dose is effective but not causing hypophosphatemia.
• Serum Calcium: To monitor for mineral imbalances.
• Plasma Aluminum Levels: To screen for early signs of accumulation (levels should generally stay below 20-30 mcg/L).
• Parathyroid Hormone (PTH): To assess bone health and mineral metabolism.

Aluminum Hydroxide does not typically cause drowsiness or impairment. However, if systemic toxicity occurs (aluminum encephalopathy), it can cause confusion and coordination issues. Until you know how you react to the medication, use caution when performing tasks requiring alertness.

Alcohol can irritate the stomach lining and increase acid production, potentially counteracting the benefits of the antacid. While there is no direct chemical interaction between alcohol and Aluminum Hydroxide, limiting alcohol intake is advised for anyone suffering from gastric hyperacidity.

There is no 'withdrawal syndrome' associated with stopping Aluminum Hydroxide. However, 'acid rebound' can occur if the medication was being used to mask significant acid reflux; symptoms may return once the buffering agent is removed. If using for phosphate binding, stopping the medication abruptly will lead to a rapid rise in serum phosphorus, which can be dangerous for heart health.

> Important: Discuss all your medical conditions, especially kidney disease or bowel issues, with your healthcare provider before starting Aluminum Hydroxide.

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.
• Bisphosphonates (e.g., Alendronate): Used for osteoporosis; their absorption is severely impaired by antacids.

• Iron Supplements: Aluminum Hydroxide can reduce iron absorption. Space doses by at least 2 hours.
• Digoxin: This heart medication may have reduced effectiveness if taken simultaneously with antacids.
• Ketoconazole and Itraconazole: These antifungal medications require an acidic environment to dissolve. Aluminum Hydroxide raises the pH, making these drugs less effective.
• Corticosteroids: Antacids may decrease the blood levels of certain steroids like prednisone.

• Citrus Juices: Like citrate supplements, orange or lemon juice can increase the amount of aluminum your body absorbs. Avoid drinking large amounts of citrus juice while taking this medication.
• Dairy Products: While not a direct interaction, high-calcium diets combined with antacids can occasionally lead to milk-alkali syndrome.

• Vitamin C: Large doses of Vitamin C may slightly increase aluminum absorption.
• Multivitamins with Minerals: Many minerals (zinc, copper, magnesium) compete for absorption and should be spaced away from Aluminum Hydroxide.

• Gastric Acid Secretion Test: Antacids will invalidate the results of this test.
• Bone Imaging: Chronic aluminum accumulation can interfere with certain radiopharmaceutical uptakes used in bone scans.
• Serum Phosphorus: The drug is intended to lower these levels; clinicians must account for this when interpreting metabolic panels.

> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. A general rule is to take other medications at least 2 hours before or 4 hours after Aluminum Hydroxide to prevent absorption issues.

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:

• Severe Renal Failure: While used in these patients, the risk of 'dialysis dementia' means it should only be used when other phosphate binders (like Sevelamer or Calcium Acetate) are not suitable.
• Upper GI Bleeding: Antacids can mask the symptoms of a significant bleed, delaying necessary endoscopic intervention.
• Dehydration: Patients who are severely dehydrated are at a much higher risk for developing bowel obstructions from aluminum salts.
• Alzheimer’s Disease: Due to the potential for neurotoxicity, clinicians may prefer non-aluminum alternatives for gastric relief in these patients.

Patients who are sensitive to Aluminum Magnesium Hydroxide or Aluminum Carbonate will likely react to Aluminum Hydroxide as well. There is no known cross-sensitivity with non-aluminum antacids like Calcium Carbonate or Sodium Bicarbonate.

> Important: Your healthcare provider will evaluate your complete medical history, including kidney function and current mineral levels, before prescribing or recommending Aluminum Hydroxide.

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.

Elderly patients are at the highest risk for complications. They are more likely to have decreased renal clearance (even if serum creatinine appears normal) and are more prone to severe constipation. Furthermore, polypharmacy (taking many medications) is common in the elderly, making the risk of drug-drug interactions with Aluminum Hydroxide very high. Clinicians often recommend magnesium-aluminum combinations or H2 blockers for this population instead.

In patients with a GFR < 30 mL/min, the risk of aluminum accumulation is high. If used as a phosphate binder, it is typically reserved for short-term use (4-6 weeks) to bring very high phosphate levels down quickly before transitioning to an aluminum-free binder. Monitoring for 'dialysis encephalopathy' (speech disturbances, tremors, seizures) is mandatory for any renal patient on long-term therapy.

No specific adjustments are needed for liver disease, but patients with hepatic encephalopathy should be monitored closely, as any electrolyte disturbance or severe constipation can worsen their mental state.

> Important: Special populations, particularly the elderly and those with kidney disease, require individualized medical assessment and frequent lab monitoring.

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.

| Parameter | Value |

|---|---|

| Bioavailability | < 1% (Minimal) |

| Protein Binding | 90-95% (to Albumin/Transferrin) |

| Half-life | Hours (Normal) / Days (Renal Failure) |

| Tmax | 0.5 - 1 hour (for neutralization) |

| Metabolism | None (Inorganic Salt) |

| Excretion | Fecal (>99%), Renal (<1%) |

• Molecular Formula: Al(OH)3
• Molecular Weight: 78.00 g/mol
• Solubility: Practically insoluble in water and alcohol; soluble in dilute mineral acids.
• Structure: It exists as an amorphous powder or as various crystalline forms (e.g., gibbsite). In medications, it is often used as a dried gel.

Aluminum Hydroxide is categorized as an Antacid and a Phosphate Binder. It is often grouped with other metal salts like Magnesium Hydroxide and Calcium Carbonate. Within the therapeutic area of nephrology, it is considered a 'metal-based phosphate binder.'