Dibasic Calcium Phosphate Anhydrous Excipient | Uses, Suppliers, and Specifications
Dibasic Calcium Phosphate Anhydrous (also known as anhydrous Calcium hydrogen phosphate, among other names) is an inorganic mineral excipient composed of Calcium ions (Ca2+) and phosphate anions in a 1:1 molar ratio. It is supplied as a white, odourless, tasteless powder or crystalline solid. It occurs as triclinic crystals.
Synonyms and Trade Names: Synonyms and Trade Names: Anhydrous Calcium Hydrogen Phosphate; Anhydrous Dibasic Calcium Phosphate; Calcium Hydrogen Phosphate Anhydrous; Anhydrous Dibasic Calcium Phosphate; A-TAB; Calcium Monohydrogen Phosphate; Calcium Orthophosphate; Di-Cafos AN; Dicalcium Orthophospahate; E341; EMCOMPRESS®; Anhydrous Fujicalin®
Uses and Applications: Tablet and Capsule Diluent and Source of Calcium
Dibasic calcium phosphate anhydrous is an inorganic calcium phosphate mineral compound. The Calcium ions (Ca2+) and phosphate anions are present in a 1:1 molar ratio. In the literature, Dibasic calcium phosphate anhydrous is known by many names and acronyms, including Anhydrous calcium hydrogen phosphate, Anhydrous dibasic calcium phosphate; Calcium hydrogen phosphate anhydrous, DCP, DCPA; MCPA, Anhydrous dibasic calcium phosphate, Calcium monohydrogen phosphate, Calcium orthophosphate, and Dicalcium orthophosphate.
Dibasic calcium phosphate belongs to a family of eleven mineral compounds that find important applications in medicine, geology, construction, and dentistry. Their methods of production, function, and applications depend on their structure, composition, solubility, and chemical stability. These related basic properties have been extensively studied; the literature is vast and interdisciplinary. In the pharmaceutical field, the three most important minerals from this family are Dibasic calcium phosphate anhydrous, Dibasic calcium phosphate dihydrate, and Tricalcium phosphate, which are used as diluents and fillers in solid dosage development.
Dibasic calcium phosphate anhydrous has the formula CaHPO4 and has no water of hydration. The “di” prefix in the common name arises because the formation of the HPO42– anion involves the removal of two protons from phosphoric acid, H3PO4. When intended to be used as a pharmaceutical excipient, Dibasic calcium phosphate anhydrous is available as a white, odourless, tasteless powder or crystalline solid. It occurs as triclinic crystals.
Chemical Structure & Identifiers
|Chemical Name||Dibasic calcium phosphate|
|CAS Registry Number||[7757-93-9]|
|UNII Code (FDA)||L11K75P92J|
|Appearance||White, odourless powder or crystalline material|
|pH||pH = 5.0 – 7.5 (20% slurry)|
|Angle of repose||330|
|Bulk density||0.85 g/ml|
|Tapped density||0.45 g/ml|
Material decomposes at 425oC to form calcium pyrophosphate.
|Moisture content||Typically 0.1 – 0.2%. The anhydrous material contains only surface-adsorbed moisture and cannot be rehydrated to form the dihydrate.|
|Particle size distribution||Average particle size varies depending on grade/supplier|
|Solubility||Practically insoluble in ether, ethanol, and water; soluble in dilute acids.|
|Specific surface area||20-45 m2/g|
|Official name||Anhydrous Dibasic Calcium Phosphate||Calcium Hydrogen Phosphate Anhydrous||Anhydrous Dibasic Calcium Phosphate|
Source of Calcium
|Anhydrous Dibasic Calcium Phosphate||Anhydrous Dibasic Calcium Phosphate|
|Appearance||White or colourless crystalline powder||White or colourless crystalline powder||White or colourless crystalline powder|
|Acid insoluble substances||specified||specified||specified|
|Heavy Metals||≤0.003%||≤40 ppm||≤31 ppm|
|Loss of Drying||n/a||n/a||≤1.0|
|Arsenic||≤3 µg/g||≤10 ppm||≤2 ppm|
|Assay||98.0 – 103.0%||98.0 – 103.0%||≥98.0%|
Key: n/a Specification is not listed
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Applications in Pharmaceutical Formulations or Technology
Dibasic calcium phosphate anhydrous is principally a tablet and capsule diluent. It is also used as a source of calcium and phosphorous in nutritional/dietary supplement tablets, where it is one of the most commonly used materials in this role, only second to Calcium carbonate. Specialty grades of Anhydrous dibasic calcium phosphate are also used in toothpaste and dentifrice formulations due to their abrasiveness.
As a pharmaceutical excipient, anhydrous dibasic calcium phosphate is selected for its compaction properties and flowability. The main deformation mechanism (of anhydrous dibasic calcium phosphate coarse-grade) during compaction is brittle fracture, which helps reduce the strain-rate sensitivity of the material, thus allowing an easier scale-up during new product development. Finally, Anhydrous dibasic calcium phosphate is nonhygroscopic and highly stable material that does not absorb water to transform into the dihydrate.
However, unlike the dihydrate, Anhydrous dibasic calcium phosphate can exhibit lamination and capping when the formulations are compressed at high pressures, particularly in formulations where the excipient is present in high proportions relative to the active ingredient, or when deep concave punches are in use. This can be reduced by introducing Microcrystalline cellulose or other suitable dry binders.
When using Anhydrous dibasic calcium phosphate, a high level of lubrication is required since the material is highly abrasive. Typical lubricant levels are >1% w/w, either Magnesium stearate or Sodium stearyl fumarate.
Commercially, Anhydrous dibasic calcium phosphate is available in two grades: a milled, poorly flowing grade, for use with wet-granulation or roller-compression processing, and a coarse, freely-flowing grade material aimed for direct compression.
Safety and Precautions
Anhydrous calcium phosphate finds wide use in pharmaceutical products, food products, and toothpastes owing to its acceptability as a relatively nontoxic and non-irritant material.
Stability and Storage Conditions
Dibasic calcium phosphate anhydrous is a nonhygroscopic and relatively stable material. Under conditions of high humidity it does not hydrate to form the dihydrate. However, the bulk material should be stored in a well-closed container in a dry place.
Workers handling Dibasic calcium phosphate must observe SHEQ precautions appropriate to the circumstances and quantity of material being processed. The fine-milled grades carry the risk of generating dust, thus the use of a respirator or dust mask is advised.
Sustainability and Environmental Impact
Dibasic calcium phosphate is a naturally-occurring mineral although it may be obtained obtained synthetically using widely available non-critical resources. Being inert and non-toxic, it is considered safe for the environment, with minimal long-term impact on ecology or marine life. Dibasic calcium phosphate achieved a total score of 78/100 by the Excipients Forum Sustainable Chemistry™ assessment scheme.
Manufacturers & Suppliers
- EMCOMPRESs® Anhydrous
- DI-CAFOS® A 12
- DI-CAFOS® A 150
- DI-CAFOS® A 160
- A-Tab® Dibasic Calcium Phosphate Anhydrous – Granular
- A-Tab® Dibasic Calcium Phosphate Anhydrous – Powder
- Callipharm® Dibasic Calcium Phosphate Anhydrous – Granular
- FUJICALIN® Anhydrous
Additional Resources (Downloads)
References and Literature Used
 Z.T. Chowhan, The effect of low- and high-humidity ageing on the hardness, disintegration time and dissolution rate of dibasic calcium phosphate-based tablets, The Journal of Pharmacy and Pharmacology, 32 (1980) 10-14.
 P.C. Schmidt, R. Herzog, Calcium phosphates in pharmaceutical tableting. 2. Comparison of tableting properties, Pharmacy World & Science : PWS, 15 (1993) 116-122.
 C. Doldan, C. Souto, A. Concheiro, R. Martinez-Pacheco, J.L. Gómez-Amoza, Dicalcium phosphate dihydrate and anhydrous dicalcium phosphate for direct compression: a comparative study, International Journal of Pharmaceutics, 124 (1995) 69-74.
 C.M. Hentzschel, A. Sakmann, C.S. Leopold, Comparison of traditional and novel tableting excipients: physical and compaction properties, Pharm Dev Technol, 17 (2012) 649-653.
 G.K. Reynolds, J.I. Campbell, R.J. Roberts, A compressibility based model for predicting the tensile strength of directly compressed pharmaceutical powder mixtures, International Journal of Pharmaceutics, 531 (2017) 215-224.
 S. Grote, P. Kleinebudde, Roll Compaction/Dry Granulation of Dibasic Calcium Phosphate Anhydrous-Does the Morphology of the Raw Material Influence the Tabletability of Dry Granules?, Journal of Pharmaceutical Sciences, 107 (2018) 1104-1111.
 H. Schlack, A. Bauer-Brandl, R. Schubert, D. Becker, Properties of Fujicalin®, A new modified anhydrous dibasic calcium phosphate for direct compression: Comparison with dicalcium phosphate dihydrate, Drug Development and Industrial Pharmacy, 27 (2001) 789-801.
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