Calcium Phosphate, Tribasic 99 calcium phosphate dihydrate can give erroneous results owing to 10 Weiner M, Bernstein IL. Adverse Reactions to Drug Formulation irreversible dehydration of the dihydrate to the anhydrous form. Agents: A Handbook of Excipients. New York: Marcel Dekker, 1989; Depending on the type of packaging and whether or not the tablet is 93–94. coated, the phenomenon can be observed at temperatures as low as 11 Eerika¨inen S et al. The behaviour of the sodium salt of indomethacin in 8 the cores of film-coated granules containing various fillers. Int J Pharm 40 C after 6 weeks of storage. As the amount of dibasic calcium 1991; 71: 201–211. phosphate dihydrate in the tablet is reduced, the effect is less easy to 12 Landı´n M et al. Chemical stability of acetyl salicylic acid in tablets observe. prepared with different commercial brands of dicalcium phosphate C The EINECS number for calcium phosphate is 231-837-1. The dihydrate. Int J Pharm 1994; 107: 247–249. PubChem Compound ID (CID) for dibasic calcium phosphate 13 El-Shattawy HH et al. Aspartame direct compression excipients: dibydrate is 104805. preformulation stability screening using differential scanning calorime- try. Drug Dev Ind Pharm 1981; 7(5): 605–619. 14 El-Shattaway HH. Ampicillin direct compression excipients: preformu- 19 Specific References lation stability screening using differential scanning calorimetry. Drug 1 Lausier JM et al. Aging of tablets made with dibasic calcium phosphate Dev Ind Pharm 1982; 8(6): 819–831. dihydrate as matrix. J Pharm Sci 1977; 66(11): 1636–1637. 15 El-Shattaway HH et al. Cephalexin I direct compression excipients: 2 Carstensen JT, Ertell C. Physical and chemical properties of calcium preformulation stability screening using differential scanning calorime- phosphates for solid state pharmaceutical formulations. Drug Dev Ind try. Drug Dev Ind Pharm 1982; 8(6): 897–909. Pharm 1990; 16(7): 1121–1133. 16 El-Shattaway HH et al. Erythromycin direct compression excipients: 3 Bryan JW, McCallister JD. Matrix forming capabilities of three calcium preformulation stability screening using differential scanning calorime- diluents. Drug Dev Ind Pharm 1992; 18(19): 2029–2047. try. Drug Dev Ind Pharm 1982; 8(6): 937–947. 4 Schmidt PC, Herzog R. Calcium phosphates in pharmaceutical tableting I: physico-pharmaceutical properties. Pharm World Sci 20 General References 1993; 15(3): 105–115. European Directorate for the Quality of Medicines and Healthcare 5 Schmidt PC, Herzog R. Calcium phosphates in pharmaceutical (EDQM). European Pharmacopoeia – State Of Work Of International tableting II: comparison of tableting properties. Pharm World Sci Harmonisation. Pharmeuropa 2009; 21(1): 142–143. http://www.edq- 1993; 15(3): 116–122. m.eu/site/-614.html (accessed 3 February 2009). 6 Landı´nMet al. The effect of country of origin on the properties of Green CE et al. R-P trials calcium excipient. Manuf Chem 1996; 67(8): 55, dicalcium phosphate dihydrate powder. Int J Pharm 1994; 103: 9–18. 57. 7 Landı´n M et al. Dicalcium phosphate dihydrate for direct compression: Innophos Inc. Product data sheet: Calcium Phosphates, 2008. characterization and intermanufacturer variability. Int J Pharm 1994; 109: 1–8. 8 Landı´n M et al. Structural changes during the dehydration of dicalcium 21 Author phosphate dihydrate. Eur J Pharm Sci 1994; 2: 245–252. RC Moreton. 9C¸ elik M, Okutgen E. A feasibility study for the development of a prospective compaction functionality test and the establishment of a compaction data bank. Drug Dev Ind Pharm 1993; 19(17–18): 2309– 22 Date of Revision 2334. 3 February 2009. Calcium Phosphate, Tribasic 1 Nonproprietary Names See also Sections 4 and 8. BP: Calcium Phosphate PhEur: Calcium Phosphate 4 Empirical Formula and Molecular Weight USP-NF: Tribasic Calcium Phosphate Ca3(PO4)2 310.20 Ca5(OH)(PO4)3 502.32 2 Synonyms 5 Structural Formula Calcium orthophosphate; E341(iii); hydroxylapatite; phosphoric acid calcium salt (2 : 3); precipitated calcium phosphate; tertiary See Sections 3 and 4. calcium phosphate; Tri-Cafos; tricalcii phosphas; tricalcium diorthophosphate; tricalcium orthophosphate; tricalcium phos- 6 Functional Category phate; TRI-CAL WG; TRI-TAB. Anticaking agent; buffering agent; dietary supplement; glidant; tablet and capsule diluent. 3 Chemical Name and CAS Registry Number Tribasic calcium phosphate is not a clearly defined chemical entity 7 Applications in Pharmaceutical Formulation or but is a mixture of calcium phosphates. Several chemical names, Technology CAS Registry Numbers, and molecular formulas have therefore Tribasic calcium phosphate is widely used as a capsule diluent and been used to describe this material. Those most frequently cited are tablet filler/binder in either direct-compression or wet-granulation shown below. processes. The primary bonding mechanism in compaction is plastic Calcium hydroxide phosphate [12167-74-7] deformation. As with dibasic calcium phosphate, a lubricant and a Tricalcium orthophosphate [7758-87-4] disintegrant should usually be incorporated in capsule or tablet 100 Calcium Phosphate, Tribasic 0.6 0.4 formulations that include tribasic calcium phosphate. In some cases 1867 (1) 1420 tribasic calcium phosphate has been used as a disintegrant. It is 1368 1446 most widely used in vitamin and mineral preparations(2) as a filler 2311 and as a binder. It is a source of both calcium and phosphorus, the 1896 two main osteogenic minerals for bone health. The bioavailability 0.0 of the calcium is well known to be improved by the presence of 2411 C cholecalciferol. Recent research reports that combinations of 1920 2145 tribasic calcium phosphate and vitamin D3 are a cost-effective 1383 log(1/R) advance in bone fracture prevention.(3) [2nd deriv. log(1/R)] In food applications, tribasic calcium phosphate powder is × 1881 widely used as an anticaking agent. See Section 18. 1433 See also Calcium phosphate, dibasic dihydrate. 1000 −1.0 −0.2 1100 1300 15001700 1900 2100 2300 2500 8 Description Wavelength/nm The PhEur 6.4 states that tribasic calcium phosphate consists of a mixture of calcium phosphates. It contains not less than 35.0% and Figure 1: Near-infrared spectrum of tribasic calcium phosphate not more than the equivalent of 40.0% of calcium. The USP32– (Ca5(OH)(PO4)3) measured by reflectance. NF27 specifies that tribasic calcium phosphate consists of variable mixtures of calcium phosphates having the approximate composi- Particle size distribution Á Á tion 10CaO 3P2O5 H2O. This corresponds to a molecular formula Tribasic calcium phosphate powder: typical particle diameter of Ca5(OH)(PO4)3 or Ca10(OH)2(PO4)6. 5–10 mm; 98% of particles <44 mm. Tribasic calcium phosphate is a white, odorless and tasteless TRI-CAL WG: average particle diameter 180 mm; 99% of powder. particles <420 mm, 46% <149 mm, and 15% <44 mm. TRI-TAB: average particle diameter 350 mm; 97% of particles < m < m 9 Pharmacopeial Specifications 420 m, and 2% 149 m. Solubility Soluble in dilute mineral acids; very slightly soluble in See Table I. water; practically insoluble in acetic acid and alcohols. Specific surface area 70–80 m2/g(4) Table I: Pharmacopeial specifications for tribasic calcium phosphate. Test PhEur 6.4 USP32–NF27 11 Stability and Storage Conditions þþ Tribasic calcium phosphate is a chemically stable material, and is Identification also not liable to cake during storage. Characters þ — Loss on ignition 48.0% 48.0% The bulk material should be stored in a well-closed container in a Water-soluble substances — 40.5% cool, dry place. Acid-insoluble substances 40.2% 40.2% Carbonate — þ 12 Incompatibilities 4 4 Chloride 0.15% 0.14% All calcium salts are incompatible with tetracycline antibiotics. Fluoride 475 ppm 40.0075% Nitrate — þ Tribasic calcium phosphate is incompatible with tocopheryl acetate Sulfate 40.5% 40.8% (but not tocopheryl succinate). Tribasic calcium phosphate may Arsenic 44 ppm 43 ppm form sparingly soluble phosphates with hormones. Barium — þ Iron 4400 ppm — 13 Method of Manufacture Dibasic salt and calcium oxide — þ Heavy metals 430 ppm 40.003% Tribasic calcium phosphate occurs naturally as the minerals Assay (as Ca) 35.0–40.0% 34.0–40.0% hydroxylapatite, voelicherite, and whitlockite. Commercially, it is prepared by treating phosphate-containing rock with sulfuric acid. Tribasic calcium phosphate powder is then precipitated by the addition of calcium hydroxide. Tribasic calcium phosphate is 10 Typical Properties alternatively prepared by treating calcium hydroxide from lime- stone with purified phosphoric acid. It may also be obtained from Acidity/alkalinity pH = 6.8 (20% slurry in water) (5) 3 calcined animal bones. Some tribasic calcium phosphate products Density 3.14 g/cm may be prepared in coarser, directly compressible forms by Density (bulk) granulating the powder using roller compaction or spray drying. 0.3–0.4 g/cm3 for powder form; 0.80 g/cm3 for granular TRI-TAB.(4) 14 Safety Density (tapped) 0.95 g/cm3 for granular TRI-TAB.(4) (4) Tribasic calcium phosphate is widely used in oral pharmaceutical Flowability 25.0 g/s for granular TRI-TAB. formulations and food products, and is generally regarded as 8 Melting point 1670 C nontoxic and nonirritant at the levels employed as a pharmaceutical Moisture content Slightly hygroscopic. A well-defined crystalline excipient. hydrate is not formed, although surface moisture may be picked Ingestion or inhalation of excessive quantities may result in the up or contained within small pores in the crystal structure. At deposition of tribasic calcium phosphate crystals in tissues. These relative humidities between about 15% and 65%, the equili- crystals may lead to inflammation and cause tissue lesions in the brium moisture content at 258C is about 2.0%. At relative areas of deposition. humidities above about 75%, tribasic calcium phosphate may Oral ingestion of very large quantities of tribasic calcium absorb small amounts of moisture.