Calcium phosphate, tribasic

• BPCalcium Phosphate
• Ph. Eur.Calcium Phosphate
• USP–NFTribasic Calcium Phosphate

Calcii phosphas; hydroxyapatite; hydroxylapatite; precipitated calcium phosphate; tertiary calcium phosphate; tricalcium phosphate; TRI-CAFOS; TRI-TAB; E341(iii)

Variable mixture of calcium phosphates, approximating to hydroxyapatite · [7758-87-4]

UNII K4C08XP666 · PubChem CID 24456

Ca3(PO4)2 (nominal); Ca10(OH)2(PO4)6 (hydroxyapatite) · 310.18 (Ca3(PO4)2); 1004.6 (Ca10(OH)2(PO4)6)

Diluent (filler), Glidant

Typical concentrations: — · Dosage forms: Solid

Used as a tablet and capsule diluent (granulated grades for direct compression), as a glidant and anticaking agent in powders and foods, and as a source of calcium and phosphate in nutritional supplements. It is also used as a buffering agent and in dental products.

A white, odourless and tasteless powder. It is not a single compound but a mixture of calcium phosphates whose composition approximates to hydroxyapatite.

Calcium content

34.0–40.0% (USP–NF)

Solubility

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

Particle form

fine powder of poor flow; granulated grades are available for direct compression

Chemically stable. Store in a well-closed container in a cool, dry place.

Like other calcium salts it reduces the absorption of tetracyclines. It dissolves in acids and may interact with acidic drugs.

Made by reacting phosphoric acid with a slurry of calcium hydroxide (milk of lime) under controlled conditions; the precipitate is filtered, dried and milled or granulated.

Used in oral pharmaceuticals and foods and regarded as non-toxic and non-irritant.

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

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

Calcium phosphate, dibasic anhydrous; calcium phosphate, dibasic dihydrate; hydroxyapatite.

Tribasic calcium phosphate has a higher calcium content than the dibasic salts, which makes it attractive for calcium-supplement tablets. The fine powder flows poorly and is mainly used as a flow aid or after granulation.