Polymeric implants brain

As for icv infusion, this is a highly invasive approach. The distribution of drug into the brain following the intracerebral implantation of a polymeric implant is also limited by diffusion, with a maximal penetration of drag into brain parenchyma of < 1 mm. 

Septicin antibacterial implant for the treatment of chronic bone infections have been developed [21-24]. The multidisciplinary concept of polymeric implants has expanded to include research on the chemistry and characterization of polymers, experimental and theoretical polymer degradation and drug release, toxicology and metabolism, and research in specific fields of applications such as cancer, proteins and hormones delivery, infectious diseases, and brain disorders. This chapter concentrates on the chemistry and characterization of polyanhydrides with a brief description on recent applications of polyanhydrides. 

Figure 4.2 Estimation of diffusion coefficients by autoradiography of tissue sections, (a) Digitized autoradiographic image of radiolabeled NGF released from a polymeric implant in a rat brain, reproduced from [18]. (b) The resulting concentration profile, obtained by scanning intensities from the autoradiographic image, and using calibrated standards to determine the local concentration the solid line indicates Equation 3-58.

Powell, E.M., M.R. Sobarzo, and W.M. Saltzman, Controlled release of nerve growth factor from a polymeric implant. Brain Research, 1990, 515, 309-311. 

Domb AJ, Rock M, Perkin C, Yipchuck G, Broxup B, Villemure JG. Excretion of a radiolabelled anticancer biodegradable polymeric implant from the rabbit brain. Biomaterials 1995 16 1069-1072. 

Domb, A.J., Rock, M., Schwartz, J., Perkin, C., Yipchuk, G., Broxup, B., Villemure, J., 1994. Metabolic disposition and ehmination studies of a radiolabeUed biodegradable polymeric implant in the rat brain. Biomaterials 15, 681—688. 

This chapter describes the transport of drug molecules that are directly delivered into the brain. For purposes of clarity, a specific example is considered polymeric implants that provide controlled release of chemotherapy. The results can be extended to other modes of administration [13,14] and other types... 

Figure 2.3 IgG levels after administration of drug delivery systems in rats. Controlled-delivery systems for antibody class IgG. The insert figures show the release of antibody from the delivery system during incubation in buffered saline. The panel (a) inset shows release from poly(lactic acid) microspheres these spherical particles were 10-100/rm in diameter. The panel (b) inset shows release from a poly[ethylene-co-(vinyl acetate)] matrix these disk-shaped matrices were 1 cm in diameter and 1 mm thick. In both cases, molecules of IgG were dispersed throughout the solid polymer phase. Although the amount of IgG released during the initial 1-2 days is greater for the matrix, the delivery systems have released comparable amounts after day 5. (a) Comparison of plasma IgG levels after direct injection of IgG (open circles) or subcutaneous injection of the IgG-releasing polymeric microspheres characterized in the inset (filled circles). The delivery system produces sustained IgG concentrations in the blood [3]. (b) Comparison of plasma IgG levels after direct intracranial injection of IgG (open squares) or implantation of an IgG-releasing matrix (filled squares) [4]. The influence of the delivery is less dramatic in this situation, probably because the rate of IgG movement from the brain into the plasma controls the kinetics of the overall process.

Freese, A., et al. Controlled release of dopamine from a polymeric brain implant in vitro characterization. Experimental Neurology, 1989, 103, 234—238. 

During, M. J., Sabel, B. A., Freese, A., Saltzman, W. M., Deutz, A. Roth, R. H., and Danger, R., 1989, Controlled release of dopamine from a polymeric brain implant In vivo characterization,.dnn. Neurol. 25 351-356. 

No. 19, 2003, p.3311-31 BIOCOMPATIBILITY OF IMPLANTABLE SYNTHETIC POLYMERIC DRUG CARRIERS. FOCUS ON BRAIN BIOCOMPATIBILITY... 

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