Polymer-based drug carriers

Polymeric microparticles have been studied and developed for several years. Their contribution in the pharmacy field is of utmost importance in order to improve the efficiency of oral delivery of drugs. As drug carriers, polymer-based microparticles may avoid the early degradation of active molecules in undesirable sites of the gastrointestinal tract, mask unpleasant taste of drugs, reduce doses and side effects and improve bioavailability. Also, they allow the production of site-specific drug targeting, which consists of a suitable approach for the delivery of active molecules into desired tissues or cells in order to increase their efficiency. 

The concept of drug binding to a carrier polymer, based on solid arguments elaborated elsewhere (20-22), is attracting increasing attention in the biochemical and biomedical research community. A number of structural prerequisites must be fulfilled by a polymer designed for drug carrier action. Specifically ... 

The aim of this chapter is to summarize some of the research findings on xylan, a natural polymer extracted from corn cobs, which presents a promising application in the development of colon-specific drug carriers. Physicochemical characterization of the polymer regarding particle size and morphology, composition, rheology, thermal behavior, and crystallinity will be provided. Additionally, research data on its extraction and the development of microparticles based on xylan and prepared by different methods will also be presented and discussed. 

The aqueous solubility of CD also enables their potential application as poly-rotaxane-based drug carriers. Yui and coworkers incorporated CD onto PEO chains in polypseudorotaxanes and polyrotaxanes [92-94], The releasing kinetics of CD from the polymer chain were studied. The release was governed by the inclusion complexation equilibrium. Biodegradation to cleave the BG units was shown to cause the release of the CD from the polyrotaxanes. 

Roux E, Francis M, Winnik FM et al (2002) Polymer based pH-sensitive carriers as a means to improve the cytoplasmic delivery of drugs. Int J Pharm 242 25-36... 

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]. 

Overall, key takeaways from the nonpoly meric paclitaxel delivery studies were that despite their improvement of angiographic parameters, paclitaxel-eluting stents without a polymer carrier did not demonstrate a positive effect on clinical outcomes, as seen with polymer-based paclitaxel elution (65), discussed in the next section. Potential reasons for the failure of such an approach could be loss of drug to the systemic circulation prior to reaching the target site during the stent deployment procedure, variability associated with the dose delivered to the lesion, and lack of control over drug-release kinetics due to the absence of a polymer carrier. 

Tamilvanan S, Venkateshan N, Ludwig A (2008) The potential of lipid- and polymer-based drug delivery carriers for eradicating biofilm consortia on device-related nosocomial infections. J Controll Release 128 2-22... 

Fatty acid based biodegradable polymers have many biomedical applications. This short review focuses on controlled drug delivery using two classes of the polymers polyanhydrides and polyesters based on fatty acids as drug carriers. Different polymer types and compositions are summarized showing the potential of these polymers as drug carriers. 

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