Medical Devices are equipment, apparatus, materials, articles, or systems for medical, dental, or laboratory use or application intended for prevention, diagnosis, treatment, rehabilitation, or contraception that do not use pharmaceutical actives to carry out their primary function.
It is a comprehensive class, which encompasses products with different types of interactions with the body, from permanent implants to products that do not meet the patient; various guides regulate it. According to RDC No. 546:2021, Medical Devices must be designed and manufactured in such a way that the characteristics and performance are guaranteed, with particular attention to:
I - Selection of materials used, particularly in terms of toxicity and, where applicable, flammability; and
II - Compatibility between materials and the biological tissues, cells, and body fluids, considering the intended purpose of the medical product.
Thus, products that come into direct contact with the patient need to be evaluated for preclinical and clinical safety (in humans). The biological evaluation addresses the non-clinical stage, where biocompatibility is assessed, which means the compatibility with living tissues or organs to prove that the product is not toxic, harmful, and does not cause immunological rejection. For this assessment, regulatory agencies from different countries, including Brazil, follow the guidelines of the ISO 10993 series.
According to ISO 10993-1:2018 (ISO, 2018a), the systematic approach to the biological assessment of medical devices as part of the risk management process must follow a decision tree that considers chemical characterization and clinical use information the device product. This process can be divided into three steps:
Biological Assessment Plan
The elaboration of the Biological Assessment Plan is a stage of searching and analyzing information. The device's intended use, all information on raw materials and manufacturing process, toxicological tests with the product or equivalent products, and literature reviews must be considered.
Initially, it is necessary to understand the type of contact with the patient, as this parameter will define the toxicological outcomes of concern. This characterization includes the following categories:
Surface contact devices: skin (intact), mucosa (intact), or injured or compromised surfaces.
External communication devices: blood vessels indirectly, tissue/bone/dentin, or circulating blood.
Implantable devices: tissue/bone or blood.
The total duration of the contact must also be defined considering single, multiple, or repeated exposures, as follows:
Limited - up to 24 hours
Extended - from 24 hours to 30 days
Permanent - more than 30 days
To proceed with the process, the physical-chemical characterization of the product is essential, and it is necessary to consider:
Configuração (tamanho, geometria, configuração da superfície)
Configuration (size, geometry, surface configuration)
Components (qualitative and quantitative)
Physical and chemical characteristics
Manufacturing process
Packaging
Another essential piece of data to be analyzed is the history of clinical use of similar products already on the market. For this, the similar product must present the same materials, production and sterilization process, and physical and geometric properties of the product under study.
After the critical analysis of all these data, the plan must bring what information is necessary to conclude the biocompatibility of the product, indicating whether additional tests are required and what these tests are.
Execution
This step details the experimental design, protocol, number of samples, and sample extraction method (when applicable). Companies must perform all tests following the guidelines established in the ISO10993 standards and under Good Laboratory Practices, generating valid results for the conclusion on the biocompatibility of the product.
Biological Assessment Report
With all the data, the biological evaluation of the product must be carried out. This report must refer to all the data used in this evaluation and make clear the rationale followed. The report must end with a conclusion on the biological safety of the medical device, which must be signed by professionals proven competent in the matter.
At the end of this process, the entire rationale that supports the biological safety of the product has been documented, and it is safe to proceed with the clinical steps to finalize the proof of the product's safety.
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Izabel Villela, PhD