Company insight
The biocompatibility of final products is a citical design input that requires planning through a lifecycle approach to ensure a compliant end product.
assessment is required to determine the impact of these substances when in contact with a patient.
For some biocompatibility test methods, the test report clearly documents results that indicate whether the testing passed the established criteria defined in the standard. Using the example of cytotoxicity testing previously described, results are generally considered passing if the grade is 2 or less. Extractables testing identifies compounds released from a device, single- use system or other material when exposed to heat and/or solvents under conditions that are considered exaggerated when compared to the real-world use. However, the results do not necessarily describe the biological risks of the identified compounds. The toxicological risk of the compounds must be assessed with consideration of variables such as the specific patient population, nature and duration of direct/indirect patient contact, and size of device or system compared to the test sample. A risk assessment performed by a qualified toxicologist is the typical means to perform this assessment.
Biocompatibility report Following the completion of all biocompatibility testing, best practice involves generating a report that summarises the results and described in detail the acceptability of results. Such a report will demonstrate alignment
between the test results and the indicated use of the product.
Some compounds identified through extractables testing may be harmful to human health at a certain level (above the threshold of toxicological concern, or TTC). When such substances are identified, the total to which a patient is exposed must be calculated and assessed based on clinical use of the product. For example, if more than one product may be used per patient, the amount of any hazardous substance is increased with use of multiple products. The results of the testing must be extrapolated to address the maximum exposure of the patient to the actual materials used. Any such limitations must be disclosed in the package insert. This strategy to link the test results with labelling and information in technical documentation will be noted in the biocompatibility evaluation report.
Maintaining biocompatibility After completion of the biocompatibility evaluation for a medical device, the materials and end product must be controlled to ensure the biocompatibility profile is not impacted. Changes in raw materials, manufacturing methods, process aids or methods for cleaning and sterilisation may each impact biocompatibility.
Adhering to rigorous change control practices ensures that any change is
Medical Device Developments /
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assessed for impact on biocompatibility. For example, a change from moist heat sterilisation to ethylene oxide sterilisation raises a new concern of ethylene oxide and ethylene chlorohydrin residue on the product. A change in raw material – even if from the same polymer family – may impact biocompatibility. A polymer provided by another manufacturer may contain a different plasticiser or colourant. A change in a mold release may result in residue on the product that impacts the biocompatibility profile. When planning for biocompatibility, partnering with Qosina allows your organisation to: ■
Select components with documented biocompatibility assessment, providing confidence that the final results of your biocompatibility assessment are likely to meet your requirements;
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Access product and material information supporting component selection for greater success in biocompatibility testing;
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Receive proactive change notifications from Qosina for component changes that require an evaluation of the biocompatibility profile of your device or system, and;
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Identify alternate components with favourable biocompatibility profiles where a change must be made to a component of your device or system. ●
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