Method for improving the oral bioavailability of a drug

A compound of formula (I)

• wherein Sugar is a beta-linked monosaccharide,
• wherein the Sugar is glucose or galactose,
• wherein optionally one or more OH groups are replaced by a group R4;
• wherein R4 is selected from the group consisting of C1-C6 alkoxy, chlorine, fluorine, cyano, CF3, NH2, C1-C6 alkyl-NH, C1-C6 dialkyl-N, C1-C6 cycloalkyl-N, C1-C6 alkyl-C(O)NH, C1-C6 alkyl-C(O)(C1-C6 alkyl)-N, HC(O)(C1-C6 alkyl)-N, C1-C6 alkyl-O—C(O)NH, C1-C6 alkyl-O—C(O)(C1-C6 alkyl)-N, and C1-C6 alkyl-O—C(O)—O;
• R1 is selected from the group consisting of H, C1-CH6 alkyl, C2-CH6 alkenyl, C2-C6 alkynyl, —R5—O—R7, —R5—S—R7, —R6—C(O)—R7, —R6—C(O)—O—R7, —R5—SO2—R7, —R5—SO2—NR7R8, C3C7 cycloalkyl, C4-C7 cycloalkenyl, a 4 to 7 membered heterocycle, aryl and (C1-C3 alkyl)-aryl;
• wherein R5 is C2 or C3 alkyl, R6 is C1-C3 alkyl, R7 and R8 are independently hydrogen or C1-C3-alkyl;
• and wherein the C3-C7 cycloalkyl, C4-C7 cycloalkenyl, a 4 to 7 membered heterocycle, aryl and (C1-C3alkyl)-aryl groups can be optionally substituted by R9,
• wherein R9 is selected from the group consisting of C1-C4 alkyl, C1-C4 alkoxy, chlorine, fluorine, cyano, CF3, amine, amide, carbamate and —C(O)O—(C1-C4-alkyl);
• R2 and R3 are both H, or one of R2 and R3 is H and the other is C1-C6 alkyl;
• X-DM represents a drug moiety wherein X is O or S;
• or a pharmaceutically acceptable salt thereof.