The present invention relates to a compound of formula (I): wherein R1 is R3-IPU and R2 is the acyloxy residue of diclofenac or naproxen, and specified by the following structures (A) wherein OH—R3-IPU is selected from (B) and R4 and R5 may be the same or different selected from (C) and salts, solvates and hydrates thereof.