The invention relates to methods of targeted drug delivery of compounds, including, chemical agents, (poly)peptides and nucleic acid based drugs (like DNA vaccines, antisense oligonucleotides, ribozymes, catalytic DNA (DNAzymes) or RNA molecules, siRNAs or plasmids encoding thereof). Furthermore, the invention relates to targeted drug delivery of compounds to extravascular and intracellular target sites within cells, tissues and organs, in particular to target sites within the central nervous system (CNS), into and across the blood-brain barrier, by targeting to glutathione transporters present on these cells, tissues and organs. Thereto, the compounds, or the pharmaceutical acceptable carrier thereof, are conjugated to glutathione-based ligands that facilitate the specific binding to and internalization by these glutathione transporters.
