Nanotechnology in Drug Delivery

Nanotechnology involves manipulating matter at the nanoscale (<1000 nm); that is, manipulations at less than thousandth of a millimeter, and for drug delivery applications this typically takes the form of creating nanoparticles (5 ∼ 800 nm) that are then used to package drug molecules and genes. By packaging pharmacologically active compounds within nanoparticles, nanomedicines are created. It is possible to control drug biodistribution and achieve therapeutic benefit with these nanomedicines. This chapter outlines the various chemistries and nanomedicine preparation strategies that have been used to produce nanoparticles and highlights the drug delivery benefits that are achievable from these nanoscale arrangements. The chemical compounds used to construct these nanomedicines are as follows: low molecular weight self-assembling amphiphiles, self-assembling amphiphilic polymers, polymer–drug conjugates, water insoluble polymers/cross-linked polymers, dendrimers, and carbon nanotubes. Engineering of these particles has produced nanomedicines that target drugs and genes to tumors and improve the brain delivery of peptides and other molecules. These particles are also capable of promoting oral drug absorption and drug transport across other biological barriers such as the cornea and the skin. Only a few of these technologies are commercially available presently, such as liposomes (e.g., Doxil®), low molecular weight micelles (e.g., Fungizone®), and polymer–drug conjugates (Oncaspar®); but the therapeutic benefits being observed in both preclinical studies and early clinical testing suggest that more of these technologies will emerge into the patient arena in the future. Keywords: carbon nanotubes; chitosan; dendrimers; drug delivery; gene therapy; liposomes; nanomedicine; nanoparticles; poly(lactide-co-glycolide)-block-(polyethylene oxide); polymer–drug conjugates