The present invention relates to novel morphine-6-glucuronide derivatives, to pharmaceutical compositions containing them and to uses thereof. Said derivatives have the following structures. The present invention relates to novel morphine-6-glucuronide derivatives, to pharmaceutical compositions containing them and to uses thereof. Said derivatives have the following structures, where the group Pcntite (A), except substituents X, is called MR36G-NR1 R2-S-, R1 = saturated or unsaturated, straight- or branched-chain C1-C10 alkyl, the alkyl chain being optionally interrupted by one or mogroup Pcntite (A), except substituents X, is called MR36G-NR1 R2-S-, R1 = saturated or unsaturated, straight- or branched-chain C1-C10 alkyl, the alkyl chain being optionally interrupted by one or more heteroatoms selected from O, S and N, R2 = H, saturated or unsaturated, straight- or branched-chain C1-C5 alkyl, or an aryl, heteroaryl or (C1-C5) alkylaryl group, R3 = Y(C=Z)R or YR, Y and Z indepre heteroatoms selected from O, S and N, R2 = H, saturated or unsaturated, straight- or branched-chain C1-C5 alkyl, or an aryl, heteroaryl or (C1-C5) alkylaryl group, R3 = Y(C=Z)R or YR, Y and Z independently = O or S, R = saturated or unsaturated, straight- or branched-chain C1-C6 alkyl with the proviso that R3 is not -O-CH3, X = H, an -S-R4-W group, or a MR,6G-NR I R2-S- group, with R4 = saturatendently = O or S, R = saturated or unsaturated, straight- or branched-chain C1-C6 alkyl with the proviso that R3 is not -O-CH3, X = H, an -S-R4-W group, or a MR,6G-NR I R2-S- group, with R4 = saturated or unsaturated, straight- or branched-chain C1 -C8 alkyl which can include amide, ester or ether bonds and W is either a d-receptor antagonist, or a K-receptor antagonist and a pharmaceutically saturated or unsaturated, straight- or branched-chain C1 -C8 alkyl which can include amide, ester or ether bonds and W is either a d-receptor antagonist, or a K-receptor antagonist and a pharmaceutically acceptable salt thereof.