The present invention relates to a compound of formula (I): wherein R1is R3-IPU and R2 is the acyloxy residue of diclofenac, and specified by the following structures: (II), (III) wherein OH-R3-IPU is selected from (IV) and R4 and R5 may be the same or different selected from H and CH3 and salts, solvates and hydrates thereof. The compounds are used for the treatment of pain such as postoperative pain following arthroscopic surgery.