Hydrogels, polymeric drug delivery

In contrast, neither acrylamide nor N-aUcylacrylamides could be anionically polymerized, due to proton abstraction from their acidic amide protons. Among such monomers, N-isopropylacrylamide (NIPAM) is the most often used, with recent interest in its polymer - poly(N-isopropylacrylamide) (PNIPAM) - having increased in exponential fashion due to its possible use as hydrogels, in drug-delivery devices, in biomedicine, and in permeation membranes - all of which reflect the polymer s water-solubiUty and thermoresponsive nature (Tc = 32 °C). 

Prokop, A., Kozlov, E., Carlesso, G. and Davidsen, ]. M. Hydrogel-Based Colloidal Polymeric System for Protein and Drug Delivery Physical and Chemical Characterization, Permeability Control and Applications. Vol. 160, pp. 119-174. 

In the last few years there have been new creative methods of preparation of novel hydrophilic polymers and hydrogels that may represent the future in drug delivery applications. The focus in these studies has been the development of polymeric structures with precise molecular architectures. Stupp et al. (1997) synthesized self-assembled triblock copolymer, nanostructures that may have very promising applications in controlled drug delivery. Novel biodegradable polymers, such as polyrotaxanes, have been developed that have particularly exciting molecular assemblies for drug delivery (Ooya and Yui, 1997). 

Polymer-based colloidal drug delivery carriers include polymeric micelles, nano- and micro- particles, or coated particles, and hydrogels [886,890,891]. These are being developed for vaccines and anti-cancer drugs, for targeting of specific treatment sites within the body, and as vehicles for ophthalmic and oral delivery. Methods for the creation of multi-layer coatings are reviewed by Sukhorukov [892] (see also Figure 14.4). Numerous examples are cited by Ravi Kumar [893]. 

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