Radiopaque polymers
Radiopaque hydrogels, in particular radiopaque hydrogel microspheres, comprising a polymer having 1,2-diol or 1,3-diol groups acetalized with radiopaque species.
1. A cross linked hydrogel polymer comprising polyvinyl alcohol (PVA) comprising 1,3-diol groups that are acetalised with a radiopaque species, according to the general formula I:
wherein X is a group of the formula:
wherein:
Z is a linking group bonded to the cyclic acetal, or is absent, such that the phenyl group is bonded to the cyclic acetal, if Z is present, then Z is C 1-6 alkylene, C 1-6 alkoxylene or C 1-6 alkoxyalkylene,
Hal is 1,2,3 or 4 covalently attached iodines.
2. A crosslinked hydrogel polymer according to claim 1 wherein the polymer comprises greater than 20% iodine by dry weight.
3. A crosslinked hydrogel polymer according to claim 1 wherein the polymer is in the form of microparticles or microspheres.
4. A crosslinked hydrogel polymer according to claim 3 wherein the polymer is in the form of microspheres with a mean diameter size range of from 10 to 2000μm.
5. A crosslinked hydrogel polymer according to claim 1 wherein the polymer has a net charge at pH 7.4.
6. A composition comprising a crosslinked hydrogel polymer according to claim 1 and a therapeutic agent wherein the therapeutic agent is absorbed into the polymer matrix.
7. A composition according to claim 6 wherein the therapeutic agent is electrostatically held in the hydrogel polymer and elutes from the polymer in electrolytic media.
8. A crosslinked hydrogel polymer according to claim 1 wherein the phenyl group is substituted by 3 or 4 iodines.
9. A crosslinked hydrogel polymer according to claim 1 wherein the polymer comprises greater than 30% iodine by dry weight.
10. A crosslinked hydrogel polymer according to claim 9 wherein the polymer comprises from 30% to 50% iodine by dry weight.
11. A crosslinked hydrogel polymer according to claim 1 wherein Z is a methylene or ethylene group or is a group (CH 2 ) p —O—(CH 2 ) q — wherein q is 0, 1 or 2 and p is 1 or 2 or is absent.
12. A crosslinked hydrogel polymer according to claim 1 wherein, Z is —(CH 2 ) 2 O(CH 2 ) 2 —, —CH 2 OCH 2 —, —(CH 2 ) 2 O—, —CH 2 O— or is absent.
13. A crosslinked hydrogel polymer according to claim 1 wherein Hal is 3 or 4 iodines.
14. A crosslinked hydrogel polymer according to claim 1 wherein Hal is 2,3,5 triiodo, 2,4,6 triiodo or 2,3,4,6 tetraiodo.
15. A crosslinked hydrogel polymer according to claim 1 wherein the polymer comprises greater than 10% iodine by dry weight.
16. A crosslinked hydrogel polymer comprising PVA and comprising 1,3-diol groups of the PVA that are acetalised with a radiopaque species, such that the hydrogel polymer comprises groups according to the general formula I:
wherein X is an iodinated aryl group.
17. A crosslinked hydrogel polymer according to claim 16 wherein X is an iodinated phenyl group.
18. A crosslinked hydrogel polymer comprising PVA and comprising 1,3-diol groups of the PVA that are acetalised with a radiopaque species, such that the hydrogel polymer comprises groups according to any of the general formulas Ia to Ie
19. A crosslinked hydrogel polymer according to claim 1 in which the polymer is a homopolymer of PVA, a copolymer of PVA or a graft polymer of PVA.
20. A crosslinked hydrogel polymer according to claim 16 in which the polymer is a homopolymer of PVA, a copolymer of PVA or a graft polymer of PVA.
21. A crosslinked hydrogel polymer according to claim 18 in which the polymer is a homopolymer of PVA, a copolymer of PVA or a graft polymer of PVA.