All medical devices have to undergo a biological evaluation of biocompatibility to fulfill the requirements in the EU Medical Device Regulation (MDR). The aim of the biological safety evaluation is to ensure that possible negative effects on human health caused by the materials in the product shall be identified and managed.
It is intended to describe the biological evaluation of medical devices within a risk management process, as part of the overall evaluation and development of each medical device. This approach combines the review and evaluation of existing data from all sources with, where necessary, the selection and application of additional tests, thus enabling a full evaluation to be made of the biological responses to each medical device, relevant to its safety in use. The term “medical device” is wide-ranging and, at one extreme, consists of a single material, which can exist in more than one physical form, and at the other extreme, of a medical device consisting of numerous components made of more than one material.
The range of biological hazards is wide and complex. The biological response to a constituent material alone cannot be considered in isolation from the overall medical device design. Thus, in designing a medical device, the choice of the best material with respect to its biocompatibility might result in a less functional medical device, biocompatibility being only one of a number of characteristics to be considered in making that choice. Where a material is intended to interact with tissue in order to perform its function, the biological evaluation needs to address this.
Biological responses that are regarded as adverse, caused by a material in one application, might not be regarded as such in a different situation. Biological testing is based upon, among other things, in vitro and ex vivo test methods and upon animal models, so that the anticipated behavior when a medical device is used in humans can be judged only with caution, as it cannot be unequivocally concluded that the same biological response will also occur in this species. In addition, differences in the manner of response to the same material among individuals indicate that some patients can have adverse reactions, even to well-established materials.
ISO 10993 series is intended for use by professionals, appropriately qualified by training and experience, who are able to interpret its requirements and judge the outcome of the evaluation for each medical device, taking into consideration all the factors relevant to the medical device, its intended use and the current knowledge of the medical device provided by review of the scientific literature and previous clinical experience.
Informative Annex A contains a table that is generally helpful in identifying endpoints recommended in the biocompatibility evaluation of medical devices, according to their category of body contact and duration of clinical exposure. Informative Annex B contains guidance for the application of the risk management process to medical devices which encompasses biological evaluation.
A medical device or material that comes in contact with the patient’s body is expected to perform its intended function without resulting in any adverse effect to a patient. Potential adverse effects can range from short-term (acute) to long-term (chronic) adverse effects to the body such as mutagenic effects. For this reason, medical devices are typically subject to biological evaluation and biocompatibility testing to evaluate the interaction between a device and tissue, cells or body fluids of the patient. The primary purpose of a device biocompatibility assessment is to protect patient from potential biological risks.
Steps:
The following series of steps can be taken while evaluating the medical devices and preparing the biological evaluation report:
- The general principles governing the biological evaluation of medical devices within a risk management process;
- The general categorization of medical devices based on the nature and duration of their contact with the body;
- The evaluation of existing relevant data from all sources;
- The identification of gaps in the available data set on the basis of a risk analysis;
- The identification of additional data sets necessary to analyses the biological safety of the medical device;
- The assessment of the biological safety of the medical device.
This document applies to evaluation of materials and medical devices that are expected to have direct or indirect contact with:
- The patient’s body during intended use;
- The user’s body, if the medical device is intended for protection (e.g., surgical gloves, masks and others).
This document is applicable to biological evaluation of all types of medical devices including active, non-active, implantable and non-implantable medical devices.
This document also gives guidelines for the assessment of biological hazards arising from:
- Risks, such as changes to the medical device over time, as a part of the overall biological safety assessment;
- Breakage of a medical device or medical device component which exposes body tissue to new or novel materials.
Other parts of ISO 10993 cover specific aspects of biological assessments and related tests. Device-specific or product standards address mechanical testing.
This document excludes hazards related to bacteria, molds, yeasts, viruses, transmissible spongiform encephalopathy (TSE) agents and other pathogens.
End Points:
Evaluation and Testing within a Risk Management Process provides a framework for determining the appropriate biocompatibility steps for planning a biological evaluation. Specific testing is dependent on the type of medical device or material and its intended use, and on the nature and duration of contact between the medical device and the body. According to the standard, an assessment for biological effects from the exposure of a medical device or material to human body can include testing such as cytotoxicity, sensitization, irritation or intracutaneous reactivity, systemic toxicity, sub chronic toxicity, genotoxicity, implantation and hemocompatibility, etc.
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