Implantable medical devices biocompatibility tests

Medical devices are used for a variety of functions in humans. This review elaborates on the types of tests used to evaluate biocompatibility of the interactions between man-made medical devices and host tissues and organs. The outcome of the response depends on the site of implantation, the species of the host, the genetic makeup of the host, the sterility of the implant, and the effect the device has on biological processes. Biological processes involved in host tissue responses to implantable medical devices reflect activation of a series of cascades that require blood proteins or other components found in the blood. 

The international standard organization ISO 10993 standard plays an important role in the assessment of the biocompatibility of a medical device. In principle, a great number of tests have to be undertaken depending on the intended use of the medical device. The standard describes tests on toxicity, carcinogenicity, and hemocompatibility, among others. Some of these tests are simple in vitro tests, while others require extensive animal experiments. For implanted medical devices,... 

P4HB and P3HB-4HB have been evaluated in preclinical tests reconunended by the FDA for medical devices. These tests include cytotoxicity, sensitization, irritation and intracutaneous reactivity, hemocompatibility, and implantation. Thus for example, P4HB films and sutures were subjected to a complete series of biocompatibility test protocols that were performed in accordance with the FDA s GLP regulations as set forth in 21 CFR, part 58, as well as ISO 10993-1. The test results confirmed that P4HB is nontoxic and biocompatible (Martin DP, personal communication). 

Biocompatibility as defined in Section 2.5 is a main prerequisite for the proper and safe use of medical devices consisting of a single material or material composition. In Section 4.5.1, it was demonstrated that the biophysical characterization of material surfaces only draws attention to some aspects of their response to biological systems. In order to assess biocompatibility for a device or a material, it is necessary to do a battery of tests depending on its intended use, with body contact ranging from transient skin contact to contact with blood to permanent implantation. Biocompatibihty is usually examined with three types of biological tests in vitro tests, animal experiments (in vivo tests), and clinical tests. 

Ure second perspective regarding the in vivo assessment of medical devices focuses on the biocompatibility of the final product, that is, the medical device and its component materials in the condition in which it is implanted. While medical devices in their firral form and condition are commonly implanted in carefully selected animal models to determine function as well as biocompatibility, it may not be appropriate to carry out all of the recommended tests necessary for regulatory approval on the final device. In these situations, some tests maybe carried out on biomaterial components of devices that have been prepared under manufacturing and sterilization conditions and other processes utilized in the final product development. 

Toxicity and biocompatibility. Adhesives used in medical devices that are implanted or in contact with the body must be tested and shown to be non-toxic, biologically inert, and compatible withblood andbody fluids. Compatibility with blood and other body fluids is especially critical. Surfaces in contact with blood must not serve a sites for coagulation and clotting of blood. Generally, qualification testing is performed to ISO-10993[ ] or to U. S. Pharmacopoeia (USP) Class VI. The two standards specify slightly different tests. The USP Class VI standard specifies acute... 

To mitigate the risk of applying a device to the human body, a series of tests such as those guided by the International Organization of Standards (ISO), are required to be performed on the device prior to human use. Biocompatibility evaluation of medical devices, based on the ISO 10993, is performed to determine the potential harmful effects from contact of the component materials with the body. BiocompatibiUty tests also evaluate the fitness and function of the devices under an implant environment. It should be noted that requirements of biocompatibility vary considerably based on the device function and design, so most regulatory evaluations are device-orientated rather than material-orientated. Usually, materials that have been proven to be biocompatible in one device have to be reevaluated for a different application. 

This book. Implantable Neural Prostheses 2 Techniques and Engineering Approaches, is part two of a two-volume sequence that describes state-of-the-art advances in techniques associated with implantable neural prosthetic devices. The techniques covered include biocompatibility and biostability, hermetic packaging, electrochemical techniques for neural stimulation applications, novel electrode materials and testing, thin-film flexible microelectrode arrays, in situ characterization of microelectrode arrays, chip-size thin-film device encapsulation, microchip-embedded capacitors and microelectronics for recording, stimulation, and wireless telemetry. The design process in the development of medical devices is also discussed. 

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