Abstract: The present invention relates to calcium salts of compounds of the general formula (I) wherein X is selected from the group consisting of CH2, S, or O; D is O or S; R8 is hydrogen or alkyl; E is an optionally substituted phenylene group; Y is a monocyclic or bicyclic substituted or unsubstituted 6-9 membered ring system which may contain one or more heteroatoms selected from N or S and which contains at least one aromatic ring; n is 0 or 1, and q is 0 or 1; with the proviso that compounds wherein X?CH2, q=0, Y=unsubstituted phenyl and E=unsubstituted phenylene are excluded; or a hydrate thereof.