Blends controlled release polymers

Blending is yet another way of manipulating the polymer properties. PTMC degrades too slowly to be useful for most drug delivery applications. Blends were prepared in an attempt to enhance and control the drug delivery rate [121]. Films were prepared from PTMC and poly(adipic anhydride) (PAA), which were partially miscible and formed macroscopically homogeneous blends. The PAA was found to act as a plasticizer and facilitated the erosion of PTMC by increasing the porosity and hydration. PTMC-PAA blends offered sustained and controllable release of an incorporated therapeutic substance as shown in Fig. 11 [121]. 

Blends of PES and poly(iV-vinyl-2-pyrrolidone) (PVP) have been tested for the use in the field of controlled release systems. The blends are immiscible due to the hydrophobic and hydrophilic nature of the polymers. However, the blends are compatible over the entire range of compositions. They exhibit a highly organized arrangement of both the phases. The PVP is dispersed unifonnly in the continuum of the PES even when it is the major component... 

Hercules Pharmaceutical Technology Report (PTR-016). In Polymer blend matrix for oral sustained drug delivery. In 25th International Symposium on Controlled Release of Bioadhesive Materials, Las Vegas, NV, June 21-26, 1998. 

Siepmann, R Siepmann, J. Walther, M. MacRae, R.J. Bodmeier, R. Blends of aqueous polymer dispersions used for pellet coating Importance of the particle size. J. Control. Release 2005,105 (3), 226-239. 

Sullad, A.G., Manjeshwar, L.S., and Aminabhavi, T.M. 2010. Controlled release of theophylline from interpenetrating blend microspheres of poly(vinyl alcohol) and methyl cellulose. J. Appl. Polym. Sci. 116 1226-1235. 

Wang, Q., Hu, X., Du, Y., Kennedy, J.F. Alginate/starch blend fibers and their properties for drug controlled release. Caibohydr. Polym. 82, 842-847 (2010)... 

Krishna Rao KSV, Subha MCS, Vijaya Kumar Naidu B, Sairam M, Mallikarjuna NN, Aminabhavi TM (2006) Controlled release of diclofenac sodium and ibuprofen through beads of sodium alginate and hydroxy ethyl cellulose blends. J Appl Polym Sci 102 5708-5718... 

The work presented here constructed a general model of starch-plastic blends as potential controlled release formulations. This model provided a practical method of predicting the kinetics of the starch digestion and product release from starch-plastic blends, thus the kinetics of pesticide release is predictable if the pesticides are either adsorbed or covalently bonded to the starch. The model was developed for starch-plastic blends. It should be adaptable to other blends of incompatible polymers, so long as one of the polymers is susceptible to enzymatic l drolysis. 

Resolute Integrity (Medtronic, Minneapolis, MN) is a 2012 PDA approved stent, that uses zotarolimus (160 g/cm ) that is 85% eluted in the first 2 months, blended with Biolinx polymer coated on a cobalt-chromium 91 micron strut. Despite its similarity with Endeavour, it was redesigned to have higher biocompatibility and controlled drug release. It was shown that Resolute had comparable results with everolimus eluting stents in the RESOLUTE All-comers trial [75-77], with other trials such as the TWENTE trial having comparable results [78]. Albeit Resolute is the only DES to be indicated specifically for diabetic patients, data from EXCELLENT and RESOLUTE-Korea show that the same could go for everolimus eluting stents [79]. 

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