Key words: biomaterials, BmCD, database
To assist review scientists and engineers in determining which materials have been used in different implant applications, and what if any standards exist for these different materials, a prototype biomaterial compendium is currently being designed at CDRH. The objective of the first phase of this project was to develop the materials/device identification tables and a controlled vocabulary data collection form which are to be used in implantable device submissions. Characteristics such as the manufacturing processes and the materials used in the construction of a device (as well as regulatory data such as 510(k) or PMA status and registration information) will be available to reviewers using the newly created tables, along with existing tables in the CDRH management information system (MIS). Long range plans for the Compendium are to include other characteristics of materials such as the chemical and physical properties and clinical/durability/biocompatibility performance.
Version 1.0 of the Biomaterials Compendium Database (BmCD) Datasheet software became available in October 1994. This program, which contains the controlled vocabulary for describing materials and processing, is designed to facilitate the creating of electronic files to describe implant devices and components.
The concept of the BmCD has been published as an abstract in the SFB Transactions and as a news release in the June 1995 issue of MDDI. Copies of the software and vocabulary have been distributed to over 200 individuals in industry, FDA, and academia.
The comments received from these aforementioned interactions have been collated into a series of modifications to the Datasheet software. The structure has been modified to make it more amenable to a biomaterials database for both regulatory and scientific purposes. Version 2.0 of the (BmCD), which incorporates many software and vocabulary modifications, has been completed and will be beta-tested in early 1996. A materials table is currently being designed in FDA which will relate device-based information in the FDA management information system with device materials data. A test materials table will be constructed and evaluated from beta-test data provided by device manufacturers on a limited number of products (approximately 100) which are currently approved. [PreME, PostMS]
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Key words: ESC, Pellethane, steroids
As part of the OST program on the modes of degradation of polyurethane by metal ion oxidation (MIO), chemical agents, or by environmental stress cracking (ESC), a study has just been completed which assessed the effect of steroids on the pellethane family of polyurethanes. Samples of pacemaker lead tubing were stretched and simultaneously exposed to solutions of three steroids of differing polarity. Solutions of cholesterol, cholesteryl acetate, and cortisone were used. Equilibrium uptakes were determined for extensions in 50% increments ranging from 50% to 250%. Polyurethanes, 2363-80A and 2363-55D, exposed to cholesteryl acetate exhibited ESC at 50% to 250% stretch with corresponding equilibrium uptakes of 0.5%. Pellethane 80A exposed to cholesterol or cortisone while under 200 or 250% strain showed ESC after 12 days exposure. The corresponding equilibrium uptakes were 0.2 and 0.5%. Pellethane 55D exhibited no ESC after 12 days exposure to cholesterol. Cortisone was effective in promoting ESC only at strains greater than 150%. These solutions were capped, and the only oxygen available was dissolved oxygen cicra 14 ppm indicating that significant oxidation of the polyurethane may not be necessary in order to obtain ESC. This study also indicates that chemical species do not have to be absorbed at high levels in order to be effective ESC agents.
These experimental results support the concept that a short-term test for
ESC of polyurethane could be used in lieu of animal experiments. The studies
confirm that strain is an important variable and that effective ESC agents
do exist at very low concentrations. The effectiveness of short term tests
as a predictive tool can only be evaluated by comparison to clinical experience
obtained via postmarket surveillance. [ProA, PostME]
Key words: plasma, bioresearch, polylactic
Polylactic acids are bioresorbable polymers used in medical device applications where functionality is required for a relatively short period of time. The use of plasmas (ionized gases, not a component of blood) is being explored as an alternative method of sterilization for plastics whose effects may be confined to the polymer surfaces. This study assessed the effect of various plasma conditions on the molecular weight distribution of polylactic acids. Size exclusion chromotography (SEC) was employed with viscosity detection and polystyrene calibration to determine the molecular weight distributions before and after treatment with various plasmas. In most instances, the effect of the plasma was to increase the molecular weight and branching of the polymer chain. These effects were most evident at the surface. A plasma produced from Argon gas produced the most consistent effects. Mechanical properties of the polylactic acid polymers were not affected by the plasmas. Crystalline polymers were more resistant to change than the amorphous materials. [ProA]
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Key words: Biotechnology Working Group, Biotechnology Strategic Plan 2000, Tissue Engineering
Primarily through the CDRH Biotechnology Working Group and the FDA Biotechnology
Coordinating Committee, a program has been developed that provides the Center
and Agency with program guidance, priorities, and planning options through
1) its broad scope of biotechnology research monitoring and assessment,
2) options development for evaluating technological applications in medical
devices, 3) promotion of science for regulatory decision making, and 4)
formulation of science and regulatory policy recommendations. The Center
coordinator for Biotechnology has provided leadership in organizing and
actively participating in several national and international biotechnology
forums. Several products, including the "Biotechnology Strategic Plan
2000," a White Paper entitled "Tissue Engineering: FDA Perspectives
1995" and an Electronic Tissue Engineering Knowledge Base (TEKB) have
been developed to provide a strong knowleedge base for the Center and to
facilitate regulatory review of new biotechnology derived products. [PreME,
ProA]
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