Aluminum hydroxide

Absorption

Approximately 17-30% of the aluminum chloride formed is absorbed.

Description

Aluminum hydroxide, insoluble in water, soluble in dilute mineral acids and alkali hydroxides (4 % suspension in water), white, amorphous powder. For other relevant properties and production, see→Aluminum Oxide, Chap. 1.1. Available as Al(OH)3·nH2O (algedrate) and algedrate hexitol complex.

Chemical properties

Aluminum hydroxide, Al(OH)3, also known as aluminum trihydroxide, aluminum trihydrate, aluminum hydrate, hydrated alumina, and hydrated aluminum oxide, is a white to whitish-yellow water-insoluble powder with a specific gravity of 2.42. Aluminum hydroxide is used as a baseforpigments, as a water repellent in textile coatings, and as an antacid in medicine. Aluminum hydroxide is soluble in hydrochloric or sulfuric acids or in sodiumhydroxide.

Chemical properties

Aluminum hydroxide adjuvant is a white hydrogel that sediments slowly and forms a clear supernatant.

The Uses of Aluminum hydroxide

aluminum hydroxide is an inorganic compound used to make a product less transparent. It is also used by formulators as a humectant, and to soften, smooth, and protect the skin. In addition it helps control product viscosity. often found in facial masks and make-up preparations.

The Uses of Aluminum hydroxide

Mainly used as an Active medicament in an Antacid Formulations, also used in manufacturing of Lake Colors, Inks, glass, effluent treatment, and fire retardants.

The Uses of Aluminum hydroxide

As absorbent, in chromatography, manufacturing of glass, paper, inks, ceramics, lubricants, cosmeticsAluminum hydroxide is used as a desiccant powder, filler in paper, plastics, rubber and cosmetics. It is used as a smoke suppressant and mordant dye. It is also used in drugs as antacid and antihyperphosphatemic. It is also used as a Claus catalyst support for waterproof fabrics. It is an important starting material for the preparation of other aluminum compounds, calcined alumina, aluminum sulfate, polyaluminum chloride, zeolites, sodium aluminate, activated alumina and aluminum nitrate. In addition, it is used as a fire retardant.

What are the applications of Application

Aluminum hydroxide is a catalyst in various chemical processes

Background

Aluminum hydroxide is an inorganic salt used as an antacid. It is a basic compound that acts by neutralizing hydrochloric acid in gastric secretions. Subsequent increases in pH may inhibit the action of pepsin. An increase in bicarbonate ions and prostaglandins may also confer cytoprotective effects.

Indications

For relief of heartburn and acid indigestion.

Production Methods

Aluminum hydroxide adjuvant is prepared by the precipitation of a soluble aluminum salt by an alkali hydroxide, or the precipitation of an alkali aluminate by acid.

Definition

aluminium hydroxide: A white crystalline compound, Al(OH)₃; r.d. 2.42-2.52. The compound occurs naturally as the mineral gibbsite (monoclinic). In the laboratory it can be prepared by precipitation from solutions of aluminium salts. Such solutions contain the hexaquoaluminium( III) ion with six water molecules coordinated, [Al(H₂O)₆]³⁺. In neutral solution this ionizes:
[Al(H₂O)₆]³⁺→H⁺ + [Al(H₂O)₅OH]²⁺
The presence of a weak base such as S^2- or CO₃^2- (by bubbling hydrogen sulphide or carbon dioxide through the solution) causes further ionization with precipitation of aluminium hydroxide
[Al(H₂O)₆]³⁺_(aq) → Al(H₂O)₃(OH)_3(s) + 3H⁺_(aq)
The substance contains coordinated water molecules and is more correctly termed hydrated aluminium hydroxide. In addition, the precipitate has water molecules trapped in it and has a characteristic gelatinous form. The substance is amphoteric. In strong bases the aluminate ion is produced by loss of a further proton:
Al(H₂O)₃(OH)_3(s) + OH^-_(aq)→
[Al(H₂O)₂(OH)₄]^-_(aq) + H₂O_(l)
On heating, the hydroxide transforms to a mixed oxide hydroxide, AlO.OH (rhombic; r.d. 3.01). This substance occurs naturally as diaspore and boehmite. Above 450℃ it transforms to γ-alumina.
In practice various substances can be produced that are mixed crystalline forms of Al(OH)₃, AlO.OH, and aluminium oxide (Al₂O₃) with water molecules. These are known as hydrated alumina. Heating the hydrated hydroxide causes loss of water, and produces various activated aluminas, which differ in porosity, number of remaining -OH groups, and particle size. These are used as catalysts (particularly for organic dehydration reactions), as catalyst supports, and in chromatography. Gelatinous freshly precipitated aluminium hydroxide was formerly widely used as a mordant for dyeing and calico printing because of its ability to form insoluble coloured lakes with vegetable dyes.

brand name

Amphojel (Wyeth-Ayerst); Dialume (Rhone-Poulenc Rorer).

Flammability and Explosibility

Non flammable

Pharmaceutical Applications

Aluminum hydroxide adjuvant is used in parenteral human and veterinary vaccines.It activates Th2 immune responses, including IgG and IgE antibody responses. It is also used for the isolation of certain serum components such as blood clotting factors.

Pharmaceutical Applications

Aluminium hydroxide (Al(OH)₃) has several medical applications. It is used as an antacid for treating heartburn as well as acid indigestion (reflux oesophagitis). It is also known to have healing properties of peptic ulcers. In patients suffering from kidney failure, who show elevated serum phosphate levels (hyperphosphataemia), Al(OH)₃ is used as a phosphate binder.
Al(OH)₃ is an amphoteric compound , which means it can react as a base or as an acid. In its application as an anti-acid, Al(OH)₃ reacts with any excess stomach acid (mainly HCl) with the formation of AlCl₃ and water .
Al(OH)₃ + 3HCl → AlCl₃ + 3H₂O
Al(OH)₃ is known to cause constipation, so formulations of anti-acids often include a combination with Mg²⁺ antacids. Usually, oral antifoaming agents, such as simethicone, are added in order to reduce bloating and discomfort/pain.

Pharmacokinetics

Gastric-peptic disease occurs as a result of an imbalance between protective factors, such as mucus, bicarbonate, and prostaglandin secretion, and aggressive factors, such as hydrochloric acid, pepsin, and Helicobacter pylori (H. pylori). Antacids work by restoring acid-base balance, attenuating the pepsin activity and increasing bicarbonate and prostaglandin secretion.

Clinical Use

Phosphate binding agent
Antacid

Safety Profile

Poison by intraperitoneal route. Human systemic effects by ingestion: fever, osteomalacia, and gastrointestinal effects. When coprecipitated with bismuth hydroxide and reduced by H2, it is violently flammable in air. Incompatible with chlorinated rubber.

Safety

Aluminum hydroxide adjuvant is intended for use in parenteral vaccines and is generally regarded as nontoxic. It may cause mild irritation, dryness, and dermatitis on skin contact. On eye contact, aluminum hydroxide adjuvant may also cause redness, conjunctivitis, and short-term mild irritation. Ingestion of large amounts may cause gastrointestinal irritation with nausea, vomiting, and constipation. Inhalation of the dried product may cause respiratory irritation and cough. Type I hypersensitivity reactions following parenteral administration have been reported.

Veterinary Drugs and Treatments

Orally administered aluminum hydroxide is used to reduce hyperphosphatemia in patients with renal failure.

Drug interactions

Potentially hazardous interactions with other drugs
Cytotoxics: concentration of dasatinib and erlotinib possibly reduced - give at least 4 hours before or 2 hours after erlotinib.

Metabolism

Not metabolized.

Metabolism

Aluminum hydroxide or oxide is slowly solubilised in the stomach and reacts with hydrochloric acid to form aluminium chloride and water. In addition to forming aluminium chloride, dihydroxyaluminium sodium carbonate and aluminium carbonate form carbon dioxide, and aluminium phosphate forms phosphoric acid. About 17-30% of the aluminium chloride formed is absorbed and is rapidly excreted by the kidneys in patients with normal renal function. Aluminium-containing antacids also combine with dietary phosphate in the intestine forming insoluble, nonabsorbable aluminium phosphate which is excreted in the faeces.

storage

Aluminum hydroxide adjuvant is stable for at least 2 years when stored at 4–308℃ in well-sealed inert containers. It must not be allowed to freeze as the hydrated colloid structure will be irreversibly damaged.

Incompatibilities

When exposed to phosphate, carbonate, sulfate, or borate anions, the point of zero charge for aluminum hydroxide adjuvant decreases.

Regulatory Status

GRAS listed. Accepted for use in human and veterinary parenteral vaccines in Europe and the USA. The limits for use in human vaccines are 0.85 mg aluminum/dose (FDA) and 1.25 mg aluminum/ dose (WHO). There are no established limits for use in veterinary vaccines. Reported in the EPA TSCA Inventory.