Radiopaque polymers

1. A radiopaque microsphere comprising a hydrophilic polymer comprising pendent groups of the formula I:

wherein:

W is independently selected from —OH, —COOH, —SO 3 H, —OPO 3 H, —O—(C 1-4 alkyl), —O—(C 1-4 alkyl)OH, —O—(C 1-4 alkyl)R 2 , —O—(C 2 H 5 O) q R 1 —(C═O)—O—C 1-4 alkyl and —O—(C═O)C 1-4 alkyl; or a group —BZ; wherein —OH, COOH, O—PO 3 H and SO 3 H maybe in the form of a pharmaceutically acceptable salt;

wherein:

B is a bond, or a straight branched alkanediyl, oxyalkylene, alkylene oxaalkylene, or alkylene group, optionally containing one or more fluorine substituents;

Z is an ammonium, phosphonium, or sulphonium phosphate or phosphonate ester zwitterionic group;

X is either a bond or a linking group having 1 to 8 carbons and optionally 1 to 4 heteroatoms selected from O, N and S;

G is a coupling group through which the group of the formula I is coupled to the polymer and is selected from 1,3 dioxolane and 1,3 dioxane;

R 1 is H or C 1-4 alkyl;

R 2 is —COOH, —SO 3 H, or —OPO 3 H 2

q is an integer from 1 to 4;

n is an integer from 1 to 4;

p is an integer from 1 to 3; and

n+p is from 2 to 5; and

wherein —COOH, —OPO 3 H 2 and —SO 3 H as well as phenolic —OH may be in the form of a pharmaceutically acceptable salt.

2. The microsphere of claim 1 , wherein the polymer is a polyhydroxylated polymer.

3. The microsphere of claim 1 , which is a polymer or co-polymer of polyvinyl alcohol and wherein the groups of the formula I are coupled through hydroxyl groups of the polyvinyl alcohol.

4. The microsphere of claim 1 , in which n is two or three.

5. The microsphere of claim 1 , in which the phenyl ring of the group of the formula I is 3,5 diiodinated, 3,4,5 tri iodinated or 2,4,6 triiodinated.

6. The microsphere of claim 1 , in which W is independently selected from —OH, —COOH, —SO 3 H, —OPO 3 H 2 , —O—(C 1-4 alkyl), —O—(C 1-4 alkyl)OH, —O—(C 1-4 alkyl)R 2 , —O—(C 2 H 5 O) q R 1 —(C═O)—O—C 1-4 alkyl and —O—(C═O)C 1-4 alkyl or a group —BZ, wherein

B is a bond, a C 1 to 6 branched or non branched alkanediyl group or a branched or non branched C 1-6 oxyalkylene group; and

Z is a group of formula II

wherein A 3 and A 4 , are the same or different and are selected from —O, —S, and —NH—; and W 1+ is —W 2 —N + R 4 3 , in which W 2 is C 1-6 alkanediyl and R 4 are the same or different and each is hydrogen or C 1-4 alkyl; and

wherein —OH, COOH, —OPO 3 H 2 and —SO 3 H may be in the form of a pharmaceutically acceptable salt.

7. The microsphere of claim 1 , in which W is selected from —OH, —COOH, —SO 3 H, —OPO 3 H 2 , —O—(C 1-4 alkyl)R 2 and —O—(C 2 H 5 O) q R 1 ; wherein —OH, —COOH, —OPO 3 H 2 and —SO 3 H may be in the form of a pharmaceutically acceptable salt.

8. The microsphere of claim 1 , in which the phenyl ring of the group of the formula I is substituted in one of the following patterns:

9. The microsphere of claim 1 , in which p is two or three.

10. The microsphere of claim 1 , which is cross-linked.

11. The microsphere of claim 1 , wherein the microsphere is in dried form.

12. The microsphere of claim 1 , wherein the microsphere is in the form of a hydrogel comprising greater than 50% water wt/wt.

13. The microsphere of claim 1 , having an iodine content of greater than 10 mg iodine per mg dried polymer.

14. The microsphere of claim 1 , which has a radiodensity of greater than 500 HU.

15. The microsphere of claim 1 , which is substituted by groups, other than those in W, which are charged at pH7.4.

16. The microsphere of claim 1 , which additionally comprises a pharmaceutical active ingredient.

17. The microsphere of claim 16 , wherein the polymer is charged and the pharmaceutical active ingredient is reversibly bound within the polymer by ionic interaction.