Body distribution of H-3-labelled dalargin bound to poly(butyl cyanoacrylate) nanoparticles after i.v. injections to mice

The blood-brain barrier (BBB) limits the penetration of substances into the brain. Because many drugs, particularly peptides, therefore can not be del ivered to the brain, carrier systems were developed to overcome this proble m. In earlier studies we demonstrated central analgesic effects of a peptid e, dalargin (dal), after systemic administration when this substance was bo und onto the surface of polybutylcyanoacrylate nanoparticles and coated wit h polysorbate 80 but not when it was given alone. The aim of the present st udy Ras to investigate the body distribution of H-3-labelled dal bound to n anoparticles compared to unbound dal after i.v. injection in mice. The radi oactivity in several tissues, including the brain, was separated in subcell ular preparations and was measured after a single i.v. injection over time. Dal radioactivity level in brain preparations was 3 times higher when the drug was bound to nanoparticles whereas the first pass pathway in liver was reduced. The results support previous data that nanoparticles can be used to transport peptides across the BBB.