In Vitro and In Vivo Evaluations of Dihydroquinoline- and Dihydroisoquinoline-based Targetor Moieties for Brain-specific Chemical Delivery Systems

Brain-targeted delivery of various drugs can be successfully achieved by chemical delivery systems (CDS) that contain a 1,4-dihydropyridine-based redox targetor moiety and undergo a sequential metabolism. However, the susceptibility of this moiety toward hydration in acidic media may limit the shelf-life of such compounds in aqueous formulation. Here, a systematic investigation of the chemical stability toward oxidation and hydration of ester and amide derivatives of 3-substituted 1,4-dihydropyridine, 1,4-dihydroquinoline, and 4-substituted 1,2-dihydroisoquinoline is reported, together with the in vitro stability and in vivo (rat) distribution of isoquinoline-based testosterone and hydrocortisone chemical delivery systems, which were selected as having the most suitable acid-resistant targetor moieties.