Modified phosphocalcic compound, injectable composition containing same

1. A phosphocalcic compound, having the following chemical composition:

Ca (10-a) (Mg, K, Na) b (PO 4 ) 6-c (HPO 4 , CO 3 ) d (OH) 2-e (F, Cl, CO 3 ) f [(OA)(OE)P(O) —CR 1 R 2 —P(O)(OA)(OE)] g , in which 0<a<9; 0<b<2; 0<c<5; 0<d<2; 0<e<2; 0<f<2; g<0.5, A and E represent H, an alkali metal, an alkaline-earth metal or nothing, R 1 represents H, OH or a halogen and R 2 represents an element chosen from a hydrogen, a halogen, an alkyl radical, an aminoalkyl radical in which the amino group optionally bears an alkyl substituent, an alkylamino radical, an alkyl radical bearing an aromatic substituent having at least one N atom wherein the aromatic substituent is not imidazolyl or pyridyl, and an alkyl radical bearing an aromatic thioether group.

2. The compound as claimed in claim 1 , wherein R 1 and/or R 2 represent Cl.

3. The compound as claimed in claim 1 , wherein R 2 is a radical containing from 1 to 6 carbon atoms.

4. The compound as claimed in claim 1 , wherein R 2 is an aminoalkyl radical NH 2 (CH) n — in which n is less than 6.

5. The compound as claimed in claim 1 , wherein R 2 is an alkylaminoalkyl radical R′R″N(CH 2 ) m — in which R′ and R″ represent, independently of each other, H or an alkyl radical containing up to 5 carbon atoms, and m is less than 6.

6. The compound as claimed in claim 1 , wherein R 2 is an alkylamino radical R c NH— in which R c is a cycloalkyl containing from 3 to 7 carbon atoms.

7. The compound as claimed in claim 1 , wherein R 2 is an alkyl radical containing up to 3 carbon atoms and bearing a phenylthio group in which the phenyl group optionally bears a halogen substituent.

8. The compound as claimed in claim 1 , wherein R 1 is OH, A and E represent H.

9. A process for preparing a modified phosphocalcic compound as claimed in claim 1 , comprising adding a gem-biphosphonic acid or an alkali metal or alkaline-earth metal salt thereof to a suspension of a precursor phosphocalcic compound in ultrapure water, stirring the reaction medium at room temperature and then recovering the formed compound therefrom by centrifugation.

10. The process as claimed in claim 9 , wherein the compound formed is purified by washing with ultrapure water, followed by filtering and drying in air at room temperature.

11. The process as claimed in claim 9 , wherein the precursor phosphocalcic compound is chosen from calcium orthophosphates with a solubility in water of greater than 4×10 −59 mol.l −1 .

12. The process as claimed in claim 11 , wherein the phosphocalcic compound is chosen from BCP, CDA, which is a calcium-deficient hydroxyapatite, and β-TCP.

13. The process as claimed in claim 9 , wherein the stirring at room temperature is maintained for a period of between 1 hour and 72 hours.

14. The process as claimed in claim 9 , wherein the acids or salts used as gem-biphosphonic compounds correspond to the formula (OY)(OX)P(O)—CR 1 R 2 —P(O)(OX)(OY) in which X or Y represent, independently of each other, H or an alkali metal or alkaline-earth metal cation, R 1 represents H, OH or a halogen, and R 2 represents:

a hydrogen or a halogen,

an alkyl radical,

an aminoalkyl radical in which the amino group optionally bears an alkyl substituent,

an alkylamino radical,

an alkyl radical bearing an aromatic substituent having at least one N atom, or

an alkyl radical bearing an aromatic thioether group.

15. A composition, comprising a suspension of the modified phosphocalcic compound as claimed in claim 1 , in a biocompatible gel or solution having a viscosity that allows the transportation of granules of between 40 μm and 500 μm in size.

16. The composition as claimed in claim 15 , wherein the biocompatible gel is a hydrogel.

17. The composition as claimed in claim 16 , wherein the gel is cellulose-based hydrogen or a hydrogel based on sodium hyaluronate.