Drug targeting by drug entrapment into ultrafine compartments as carriers

The incorporation of drugs into vesicles is one of several technological methods for the optimization of targeted drug delivery and controlled drug targeting. The main problems will always remain

? To design inert auxiliary accompanying materials in order to overcome side reactions

? To use body-friendly and biodegradable macromolecular carrier materials for the therapeutic system

? To miniaturize the dosage form dramatically in the submicroscopic size range in order to eliminate foreign body irritations

? To develop ultrafine solid and amorphous vesicular compartments (nanocapsules, nanopellets, nanoparticles) to get stable systems with good tissue transfer and organ targeting properties

The actual stand of the incorporation of drugs and biologic active material into ultrafine colloidal solid capsules is reviewed here as for instance:

? Immunoactive material

? Fluorescent indicators in body fluids

? Controlled and sustained release systems

? Nonspecific drug targeting of the first-order (passage through endothelial tissues)

? Second-order targeting (a specific transparenchymal migration), and a highly specific targeting of the third-order (transcellular passage, especially lysosomal transports)

Examples for some of these applications are given. It can be shown that such ultrafine vesiculated capsules offer some advantages when applied parenterally, but also partly for oral application. In the future, still more studies are necessary finally to clarify the importance and practical use of such ultrafine targeting carriers.