Calcium phosphate, dibasic anhydrous

• BPAnhydrous Calcium Hydrogen Phosphate
• JPAnhydrous Dibasic Calcium Phosphate
• Ph. Eur.Calcium Hydrogen Phosphate, Anhydrous
• USP–NFAnhydrous Dibasic Calcium Phosphate

A-TAB; Anhydrous Emcompress; calcium hydrogen orthophosphate; calcium monohydrogen phosphate; dicalcium orthophosphate; DI-CAFOS AN; Fujicalin; phosphoric acid calcium salt (1:1); E341(ii)

Calcium hydrogen phosphate · [7757-93-9]

UNII L11K75P92J · PubChem CID 24441

CaHPO4 · 136.06

Diluent (filler)

Typical concentrations: — · Dosage forms: Solid

Used as a diluent and filler in tablets and capsules, in both direct compression and wet granulation; coarse or porous grades flow well and are designed for direct compression and can form a large part of the tablet. It is also used as an abrasive in toothpastes, as a calcium and phosphorus source in nutritional supplements, and in foods.

A white, odourless and tasteless powder or crystalline solid. Commercial grades range from fine powders to coarse granules and porous, spray-dried particles.

Solubility

practically insoluble in water and ethanol; soluble in dilute hydrochloric and nitric acids

Loss on ignition

6.6–8.5% w/w (from conversion to calcium pyrophosphate)

Hygroscopicity

non-hygroscopic; does not hydrate to the dihydrate under normal storage conditions

Crystal form

triclinic (monetite)

Compaction behaviour

consolidates mainly by brittle fracture; relatively insensitive to lubricant level and tableting speed

Stable and non-hygroscopic at room temperature. Store in a well-closed container in a cool, dry place.

Calcium salts reduce the bioavailability of tetracycline antibiotics. The particle surface is slightly alkaline, so it may be unsuitable for drugs that degrade in an alkaline microenvironment.

Made by reacting phosphoric acid with calcium hydroxide or calcium carbonate under controlled conditions and drying the precipitate, or by dehydrating the dihydrate; the conditions of precipitation and drying determine particle size and porosity.

Widely used in oral pharmaceuticals, foods and toothpastes and regarded as non-toxic and non-irritant.

Observe normal precautions for the quantity handled. Avoid inhaling the dust; eye protection, gloves and a dust mask are recommended.

GRAS listed. Accepted as a food additive in Europe (E341(ii)). Included in the FDA Inactive Ingredient Database (oral capsules and tablets) and in non-parenteral medicines licensed in Europe.

Calcium phosphate, dibasic dihydrate; calcium phosphate, tribasic; calcium carbonate.

Unlike the dihydrate, the anhydrous form contains no water of crystallisation, so it is preferred for moisture-sensitive drugs and for processes involving heat. Being insoluble, tablets with a high content may need a disintegrant; the material is also fairly abrasive to tooling.