Oral drug delivery diffusion-controlled release

Another facet of parenteral drug delivery is the implanted device, and this is perhaps the most promising and most readily commercialised area for responsive and/or active polymers. For an implanted vehicle or depot, drag release rate is controlled by dissolution and/or diffusion in the formulation, or for solid polymer implants by diffusion and/or degradation of the polymer. For more complex polymer hydrogels, the release can be controlled by the linking chemistries, and these can be made responsive to a wide variety of stimuli such as enzymatic action, redox potential and so on, as well as those noted above for the oral route. 

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