A Mineral Excipient at the Heart of Tableting
Dicalcium phosphate is a mineral excipient widely used in tablet manufacturing. Its main role is as a diluent, also known as a filler.
It adds bulk and mass when the active ingredient dose is low, while offering excellent compression properties. It can also serve as a source of calcium and phosphorus.
A Mineral Origin, Not Chemical Synthesis
Unlike synthetic active ingredients, dicalcium phosphate has a mineral origin. It can be obtained in two ways:
- extracted and then purified from natural phosphate rock (phosphate ore); or
- produced by synthesis, by neutralizing phosphoric acid with a calcium source (calcium hydroxide or carbonate).
Pharmaceutical-grade material is then purified and controlled according to pharmacopoeia standards.
Two Crystalline Forms: Brushite and Monetite
It is an inorganic salt combining the calcium ion (Ca2+) and the hydrogen phosphate ion (HPO4 2-). It exists in two main forms:
- the dihydrate form (CaHPO4·2H2O), a mineral known as brushite, particularly valued for direct compression; and
- the anhydrous form (CaHPO4), known as monetite.
Properties Built for Tablet Manufacturing
Dicalcium phosphate is:
- insoluble in water and chemically stable;
- low in reactivity, making it compatible with many active ingredients;
- endowed with good compression properties (especially the dihydrate form), which facilitates the manufacture of solid tablets; and
- slightly abrasive.
From Pharmaceutical Excipient to Food and Beyond
The main uses of dicalcium phosphate are:
- diluent / filler: adds volume and weight to tablets with a low active ingredient dose;
- direct compression agent (specific grades), which simplifies manufacturing;
- source of calcium and phosphorus in certain dietary supplements and fortified foods; and
- non-pharmaceutical uses: food additive (E341), mild abrasive in some toothpastes, and animal feed.