Prodrugs of non-steroid anti-inflammatory agents (NSAIDS)

A compound of formula (I):

• wherein:
• R1 represents an immobility promoting unit (IPU) with a molecular weight lower than 1000 g/mol and a pKa of between 4 and 7.6 at 37° C., wherein the IPU is selected from the group consisting of:
• wherein R3 is attached on any ring carbon or any nitrogen of the IPU and R3 is straight or branched C1-8 alkyl or alkoxyalkyl, with the proviso that when R3 is attached on a nitrogen atom R3 is not —CH2—
• R4 and R5 are each independently hydrogen, straight or branched C1-8 alkyl, alkoxyalkyl or phenyl, or when R1 is a phenylamino or benzimidazolyl moiety as set forth above, R4 may be R3, or when R1 is an imidazolyl moiety as set forth above, R5 may be R3;
• —O—(C═O)—R2 represents an acyloxy residue of a carboxylic acid group of;
• and
• x is 1;
• salts, solvates or hydrates thereof,
• wherein the aqueous solubility of the compound is pH dependent, such that the aqueous solubility at a pH between 2 to 6 pH units lower than a pH of a physiological fluid having a pH of from 6 to 8 is at least 100 times higher than its aqueous solubility at the pH of the physiological fluid.