Degradable polymeric implants

Title Degradable Polymeric Implantable Medical Devices with a Continuous Phase and Discrete Phase... 

Non-degradable polymeric implants are divided into two main types (see also section 3.2) ... 

Poly(ethylene-co-vinyl acetate) (EVA copolymer) is also widely used as a non-degradable polymeric implant. These copolymers have the advantages of ... 

Reservoir/matrix hybrid-type non-degradable polymeric implants are also available. Such systems are designed in an attempt to improve the M t1/2" release kinetics of a matrix system, so that release approximates the zero-order release rate of a reservoir device. Examples of these types of systems include ... 

Such limitations prompted scientists to develop biodegradable polymeric implants. Degradation can take place via ... 

The drag release for biodegradable polymeric implants is governed not by diffusion through a membrane, but by degradation of the polymer membrane or matrix. 

The release rate of a dmg from conventional non-degradable matrix-type polymeric implant usually decreases over time. Describe a technique that can be used to overcome this problem. 

Which polymer is most extensively used as non-degradable nonporous membrane to develop reservoir-type polymeric implants ... 

Corrosion of metallic surgical implant materials used in orthopedic, cardiovascular, and dental devices resulting in the release of metal ions to tissues, and degradation of the physical properties of polymeric implant materials due to interactions with tissue fluids and/or blood... 

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 3 lists the relative water sorption of a variety of polymeric blomaterlals. Figure 4 Indicates the most commonly encountered biodegradable repeating bond units In polymer backbones. Such polymers generally degrade via hydrolysis reactions. Blodegradablllty may or may not be desired In a polymeric Implant.

This degradation process can also release biomaterial-associated components such as chemical initiators, inhibitors, residual monomers, antioxidants, or plasticizers, which can invoke adverse response from the host immune system [47], Though the in vivo biodegradation mechanism of polymeric implants is not firmly understood, hydrolysis and oxidation are two chemical pathways often implicated in this process [45],... 

Given the complex biological and chemical interaction between the polymeric implants and the in vivo environment of the host, the physiochemical properties of the polymers must be carefully considered in the selection of polymeric biomaterials that are biochemically appropriate for specific applications in implantable prostheses. Overall, the ideal material should minimize its adverse effects on the host tissues and immune system while resisting hydrolytic and oxidative degradation to achieve successful device integration and the intended long-term functionality. In addition, the choice of materials depends not only on the functions of the prostheses but also on other factors such as the site of implantation, the age group of recipients, and the intended period of use. 

Degradation of implanted polymeric material through hydrolysis is generally occurred in the case of hydrophilic polymers. The adsorbed water acts as a plasticizer, altering the physical properties of the material and resulted in dimensional instability of the device or implant [20, 21]. 

Physical degradation of implanted polymeric material is mainly due to the interaction of the materials by means of temperature, air, light and high energy radiation [21]. 

The rate of degradation of the polymeric implant in the biological medium alters material biocompatibility. Generally, the compatibility of polymeric materials depends either on initial interactions with physiological components or on the stability of implants in the surrounding biological medium. 

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