What Are the Most Common Uses for Aluminum Hydroxide?

Aluminum hydroxide (Aluminium hydroxide), chemical formula Al (OH) ₃ , is a hydroxide of aluminum. Aluminum hydroxide can react with acids to form salts and water, and can also react with strong bases to form salts and water, so it is an amphoteric hydroxide. Because it shows a certain acidity, it can also be called aluminate (H3AlO3). However, when actually reacted with a base, tetrahydroxyaluminate ([Al (OH) 4]-) is formed. Therefore, it is usually regarded as monohydrated aluminic acid (HAlO2 · H2O), which is divided into industrial grade and pharmaceutical grade according to its use.

Aluminum hydroxide (Aluminium hydroxide),

Aluminum hydroxide is the largest and most widely used inorganic flame retardant additive. As a flame retardant, aluminum hydroxide can not only be flame retardant, but also prevent smoke, no drips, and no toxic gas. Therefore, it has been widely used and its usage has increased year by year. Scope of application: thermosetting plastics, thermoplastics, synthetic rubber, coatings and building materials. At the same time, aluminum hydroxide is also the basic raw material of aluminum fluoride required in the electrolytic aluminum industry. Aluminum hydroxide is also widely used in this industry.

Aluminum hydroxide is commonly used in the treatment of gastric hyperacidity. The main component of gastric acid is hydrochloric acid. Aluminium hydroxide reacts with gastric acid to generate non-toxic and harmless aluminum chloride. The reaction equation is: Al (OH) 3 + 3HCl == AlCl3 + 3H2O

The reason why aluminum hydroxide is used to neutralize gastric acid, but not sodium hydroxide or calcium hydroxide, is because these two substances are strong, but they are harmful to the human body and corrosive, so they cannot be used to neutralize gastric acid.

Pharmacological action of aluminum hydroxide

Aluminum hydroxide is a typical and commonly used antacid, which has the functions of anti-acid, absorption, local hemostasis and protection of ulcers. Aluminum hydroxide has a chemical reaction that neutralizes or buffers the existing gastric acid in the stomach, but has no direct effect on the secretion of gastric acid, and its anti-acid effect is slow and long-lasting. The neutralization and buffering effect of aluminum hydroxide can cause the pH value of gastric contents to rise, thereby alleviating the symptoms of hyperacidity. However, it must be noted that the ability to neutralize acids is lower than that of magnesium-containing preparations and calcium carbonate, and higher than that of aluminum carbonate and sodium bishydroxyaluminum carbonate. When aluminum hydroxide interacts with gastric acid, the produced aluminum chloride has an astringent effect and can locally stop bleeding, but it may also cause constipation. When aluminum hydroxide interacts with gastric acid, the produced aluminum chloride has an astringent effect and can locally stop bleeding, but it may also cause constipation. Aluminum hydroxide is also mixed with gastric fluid to form a gel, covering the surface of the ulcer to form a protective film, which plays a mechanical protective role. In addition, since aluminum ions are combined with phosphate in the intestine to form insoluble aluminum phosphate excreted from feces, uremia patients can reduce the absorption of intestinal phosphate after taking large doses of aluminum hydroxide, thereby reducing acidemia (but Attention should be paid to the above-mentioned side effects).

Pharmacokinetics of aluminum hydroxide

A small amount of aluminum hydroxide is converted into soluble aluminum chloride in the stomach, absorbed from the gastrointestinal tract, and excreted by the urine. Most of them are excreted from feces in the form of aluminum phosphate, aluminum carbonate and fatty acid salts; aluminum hydroxide acts slowly, and the length of time in the stomach is related to the speed of gastric emptying. The effect of taking the drug on an empty stomach can last for 20 to 30 minutes, and the aging effect can be extended to 3 hours after taking a meal 1 to 2 hours.

Aluminium hydroxide indication

1. It can alleviate the symptoms of hyperacidity combined with acid reflux, and is suitable for the treatment of gastric ulcer and duodenal ulcer, reflux esophagitis and upper gastrointestinal bleeding.

2. When used in combination with calcium and vitamin D, it can treat neonatal hypocalcemia (tetany of the hands and feet).

Aluminum hydroxide contraindications

1. Patients with fractures should not take it.

2. Patients with hypophosphatemia (such as malabsorption syndrome) should not take it.

3. Not suitable for premature infants and infants (because infants and young children can easily absorb aluminum, there is a risk of aluminum poisoning).

4. Bile, pancreatic juice and other strong alkaline digestive juice secretion or excretion disorders should not be used.

Matters needing attention for aluminum hydroxide

1. (1) Renal insufficiency. (2) Those with long-term constipation.

2. For appendicitis or acute abdomen, taking aluminum hydroxide can aggravate the condition and increase the risk of perforation of the appendix.

3. Since the aluminum hydroxide tablets are not as effective as gels, gels are commonly used.

4. Aluminum hydroxide gel should be used in the treatment of gastric bleeding, because tablets can clot with the blood to block the intestinal tract.

5. When used to neutralize gastric acid, it must be taken 1 to 2 hours after a meal.

6. Avoid taking other drugs within 1 to 2 hours after taking aluminum hydroxide.

7. Because aluminum hydroxide can hinder the absorption of phosphorus, it should not be used in large doses for a long time. For long-term use, add phosphate to your diet.

8. To prevent constipation, alternate with magnesium trisilicate or magnesium oxide.

9. Patients with abnormal renal function should pay special attention to the danger of aluminum accumulation in the body when taking aluminum hydroxide. If the serum aluminum content exceeds 150 g / ml, or if there is a sign of encephalopathy, the drug should be stopped immediately. For dialysis patients, the aluminum content in the dialysate should not exceed 10 g / ml.

Aluminum hydroxide adverse reactions

1. Common constipation, related to the dose. Taking large doses for a long time can cause severe constipation, and can even form fecal clumps, causing intestinal obstruction. Aluminum may also cause an increase in serum bile acid concentration. This effect is dose- and time-dependent, and accompanied by a decrease in bile flow, it can induce liver and bile dysfunction.

2. Metabolic / endocrine system: Aluminum hydroxide can be combined with intestinal phosphate ions to form insoluble aluminum phosphate, which is not absorbed by the gastrointestinal tract, resulting in a decrease in serum phosphate concentration and an increase in calcium content. Causes abnormal calcium and phosphorus metabolism and affects bone formation. Long-term use in large quantities can cause hypophosphatemia, osteoporosis and osteomalacia.

3. Nervous / mental system: A small amount of aluminum hydroxide is converted into soluble aluminum chloride in the stomach and absorbed from the gastrointestinal tract. Renal insufficiency can lead to increased aluminum ion concentration in the blood. Patients with renal failure who take aluminum hydroxide for a long time can cause aluminum poisoning and psychiatric symptoms, especially in patients undergoing hemodialysis, which can produce dialysis dementia, which manifests as muscle pain, convulsions, nervousness or irritability, abnormal taste, and respiratory changes. Symptoms such as slowness and extreme fatigue.

4. Blood system: People with renal insufficiency can lead to an increase in blood aluminum ion concentration, and aluminum is one of the main causes of anemia in patients with advanced kidney disease. For patients with uremia, excessive aluminum may cause small cell hypochromic anemia, which may be caused by inhibited hemoglobin synthesis, decreased enzyme activity, and decreased iron utilization. Reducing the amount of aluminum hydroxide or using ferriamine chelator can effectively correct this symptom.

5. Skin: When taking aluminum hydroxide, patients who are more sensitive to aluminum are injected with diphtheria, tetanus toxoid and pertussis vaccine (DTP triple vaccine), itching, eczema-like lesions and pigmentation often occur at the injection site. .

Usage and dosage of aluminum hydroxide

1. Aluminum hydroxide gel: 5-8ml each time, 3 times a day, usually taken 1h before meals. The dose can be doubled in severe cases.

2. Aluminum hydroxide tablets: 0.6-0.9g each time, 3 times a day, usually taken 1h before meals.

Interaction of aluminum hydroxide drugs

1. Combined with cimetidine or ranitidine, it is effective to relieve the symptoms of duodenal ulcer pain, but it is generally not recommended to use both together within 1h, because cimetidine or ranitidine can be used The absorption is reduced.

2. Aluminum hydroxide contains polyvalent aluminum ions, which can form complexes with tetracycline drugs and affect their absorption, so the two should not be used in combination.

3.Aluminum hydroxide can interfere with warfarin, dicoumarin, quinine, quinidine, chlorpromazine, propranolol, indomethacin, isoniazid, iron salts, and barbi through various mechanisms Absorption or elimination of proper drugs will affect the efficacy of the above drugs, and should be avoided as much as possible.

4. Bile salts can be adsorbed when the amount is large, thus reducing the absorption of fat-soluble vitamins and reducing the blood concentration of the drug. Avoid using both at the same time.

5. When combined with digitalis drugs, it can affect the absorption of the latter and reduce its blood concentration. Both should be avoided at the same time.

6. When used with enteric-coated tablets, it can accelerate the dissolution of enteric coatings and have a stimulating effect on the stomach and duodenum.

7. Patients on dialysis taking allopurinol and aluminum hydroxide at the same time can cause a sharp rise in serum uric acid content, which may be caused by aluminum hydroxide reducing the absorption of allopurinol.

8. The combination of aluminum preparation and citrate may have special risks. Some studies have shown that the combination of the two may cause a sharp rise in blood aluminum content.

Aluminum hydroxide expert review

Aluminum hydroxide is an acid and astringent. Mainly used for hyperacidity, stomach and duodenal ulcers. The curative effect is remarkable, the use is safe, and there are few adverse reactions. It is a first-line drug for antacids. Long-term use can cause constipation, and renal dysfunction may increase aluminum ions in the blood. Long-term use may cause dementia, etc. The elderly should pay special attention. ^[1]