Medicinal Chemistry drives drug targeted delivery: a successful interplay

Targeted drug delivery is object of an intense research. A medicinal chemistry approach allowed us to modify an opioid peptide in order to remove the opioid activity and retain the ability to cross the blood-brain barrier. Polyester-based nanoparticles (Np) surface-decorated with this peptide were shown to be able to deliver loperamide (a model drug) into CNS, as well as cholesterol (for the treatment of Huntington’s disease) and albumin (a model of a cargo protein). With a view of clinical translation, however, polyester Np seems to be not well suited for CNS diseases. Thus, we decided to use our peptide in alternative ways other than as a conjugate with the carboxyl group of the polyester PLGA, starting material for the production of the Np. We develop a new synthetic procedure that allow the conjugation of the peptide with substrates containing hydroxyl groups, less reactive than the carboxy group of the polyester (we considered as a substrate the poly(vinyl alcohol)), as well as a linker that could be inserted between a cargo and the peptide targeting moiety. At the same time, we moved towards lipidic carriers, a kind of delivery agents already clinically available. To gain experience on these carriers, we designed rifampicin-loaded Solid Lipid Nanoparticle assemblies (SLNas), for a direct intramacrophagic antitubercular therapy using Dry Powder Inhaler (DPI) devices and, in the first instance, methyl mannopyranoside as targeting ligand, able to interact with mannose receptors present on macrophages. Results obtained will be presented and discussed.