Polyurethanes drug delivery

Ethylene vinyl acetate has also found major applications in drug delivery. These copolymers used in drug release normally contain 30-50 wt% of vinyl acetate. They have been commercialized by the Alza Corporation for the delivery of pilocarpine over a one-week period (Ocusert) and the delivery of progesterone for over one year in the form of an intrauterine device (Progestasert). Ethylene vinyl acetate has also been evaluated for the release of macromolecules such as proteins. The release of proteins form these polymers is by a porous diffusion and the pore structure can be used to control the rate of release (3). Similar nonbiodegradable polymers such as the polyurethanes, polyethylenes, polytetrafluoroethylene and poly(methyl methacrylate) have also been used to deliver a variety of different pharmaceutical agents usually as implants or removal devices. 

Biodegradable polyurethanes have been proposed and studied before (9-72). The difference in our study is the inclusion of a phosphoester linkage instead of the commonly used polyester component. This seems to provide more flexibility as the side chain of the phosphate or phosphonate can be varied. For controlled drug delivery applications, drugs can be linked to this site to form a pendant delivery system. Moreover, for certain medical applications, fast degradation rate is obtainable by the introduction of these hydrolyzable phosphoester bonds. With the LDI based polyurethanes, drugs or other compounds of interest can also be coupled to the ester side chain of the lysine portion. 

Ueda, T., Yamaoki, T., Miyamoto, M., Kimura, Y., Sasatani, H., and Kim, S.I., Baeterial reduction of azo compounds as a model reaction for the degradation of azo-eontaining polyurethane by the action of intestinal flora. Bull Chem. Soc. Jpn., 69 1139-1142 (1996). Krishnaiah, Y.S., Satyanarayana, S., and Prasad, Y.V., Studies of guar gum eompression-coated 5-aminosalicylic acid tablets for colon-specific drug delivery. Drug-Dev. Ind. Pharm., 25 651-657 (1999). 

Sucrose acrylate derivatives can be converted into polymers and hydrogels that can be used as flocculants, water adsorbents, bioimplantables, and drug delivery devices (42). Sucrose ethers have applications as surfactants and surface coatings, and as feedstocks for synthesis of polyurethane foams and... 

Dev Y Eigler N, Sheth S, et al. Kinetics of drug delivery to the arterial wall via polyurethane-coated removable nitinol stent comparative study of two drugs. Cathet Cardiovasc Diagn 1995 34 272-278. 

Other Synthetic Biodegradable Polymers Although well investigated for drug delivery, polyorthoesters, polyurethanes, and polyamides have found limited application as nanoparticles. A report documents the synthesis and characterization of polyorthoester nanoparticles [105],... 

Poly(propylene oxide) is typically obtained by base catalyzed anionic polymerization of propylene oxide [12]. Both stereospecific and atactic forms are known. The polymer is used as a soft polyether unit in polyurethane elastomers and foams in polymer electrolytes as surfactants (lubricants, dispersants, antistatic agents, foam control agents) in printing inks, as solubilizers in hydraulic fluids, coolant compositions in various medical applications (protective bandages, drug delivery systems, organ preservation, dental compositions), etc. 

Among the many classes of polymeric materials now available for use as biomaterials, non-degradable, hydrophobic polymers are the most widely used. Silicone, polyethylene, polyurethanes, PMMA, and EVAc account for the majority of polymeric materials currently used in clinical applications. Consider, for example, the medical applications listed in Table A.l most of these applications require a polymer that does not change substantially during the period of use. This chapter describes some of the most commonly used non-degradable polymers that are used as biomaterials, with an emphasis on their use in drug delivery systems. 

As we shall see in Chapter 15, polyurethane is a polymer of choice for a wide variety of biomedical applications. Polyurethane is used extensively in the construction of devices such as vascular prostheses, membranes, catheters, plastic surgery, heart valves, and artificial organs. Polyurethanes are also used in drug delivery systems such as the sustained and controlled delivery of pharmaceutical agents, for example, caffeine and prostaglandin. ... 

Polyurethane Good chemical resistance, toughness, good processabihty Catheters, tubing, LV. connectors, drug delivery systems... 

Urethane polymer, when fully reacted, is completely chemically inert. Polyurethane micelles are thus used for some drug delivery processes. 

TABLE 7.1 List of Published Patents for Drug Delivery, Tissue Engineering, and Medical Devices Using Biomedical Polyurethanes ... 

S.H. Kuo, P. Kuzma, Long term drug delivery devices with polyurethane based polymers and their manufacture, US8343528 B2, US 12/907,717, 2013. 

N. Shelke, M. Sairam, S. Halligudi, T.M. Aminabhavi, Development of transdermal drug delivery films with castoroil based polyurethanes, J. Appl. Polym. Sci. 103 (2) (2007) 779-788. 

S. Moura, L. Lima, S. Andrade, A. Da Silva-Cunha, R. 6refice, E. Ayres, G. Da Silva, Local drug delivery system inhibition of inflammatory angiogenesis in a murine sponge model by dexameth-asone-loaded polyurethane implants, J. Pharm. Sci. 100 (7) (2011) 2886-2895. 

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