Delivery of Hydrophobic Drugs through Self-Assembling Nanostructures

Many potent therapeutic agents possess a high degree of hydrophobicity which can greatly impede their solubilization in aqueous media and thus hamper their oral or parenteral administration. In order to circumvent this limitation, novel drug delivery systems, such as polymeric micelles and lipid-based nanocapsules, are being developed. In general, these nano-sized carriers contain a hydrophobic core which provides the necessary environment to solubilize poorly water-soluble drugs. In addition, when administered intravenously, they can passively target inflamed or cancerous tissues due to the enhanced permeation and retention (EPR) effect, potentially improving the therapeutic efficacy of the drug while reducing its toxicity. Alternatively, the limited oral bioavailability of hydrophobic agents can be improved by selectively releasing the drug in its molecular form close to the absorption site. Polymeric micelles containing pH-sensitive moieties and loaded with a poorly water-soluble drug can dissociate and release their payload in the intestine. This presentation will focus on injectable polymeric and lipidic vectors for hydrophobic anti-cancer agents and on pH-sensitive polymeric micelles as promoters of the oral bioavailability of poorly water-soluble drugs [1].