The present invention relates to modified oligonucleotides of 5-50 nucleotide residues, wherein at least 25% of the nucleotides are independently modified at the 2&prime position to comprise the structure of formula (I), wherein base is a purine or pyrimidine moiety and R1, R2, R3, R4, p and q are as defined in the description. The modified oligonucleotides comprising said structures are useful as medicaments for enhancement of drug uptake in oligonucleotide based therapy in humans and animals.
