Biocompatibility evaluation of a series of autoinjector medical devices

Client

A UK medical devices manufacturer.

Background

The company manufactures a range of parts for use as components in a variety of medical devices. In use, the component parts make brief (a few seconds, approximately) intact skin contact with the hands of users/patients. Information on the composition of the relevant (patient-contacting) device components was provided by the client and full compositional details were sought from the supply chain.

Project goals

Bibra was asked to evaluate the biocompatibility of a series of single-use, autoinjector medical devices, focusing on the plastic components, and to provide a conclusion on health risks associated with their clinical use.

Approach and outcome

ISO 10993-1 includes a device-data matrix that defines the biocompatibility endpoints that should be considered for medical devices. These endpoints depend upon the type of device, the type of tissue it may contact, and the duration of that contact. Bibra conduced an initial screen of the material constituents and, based on the nature of the device use (patient body contact and duration), recommended that the biological evaluation be limited to the following endpoints: cytotoxicity, irritation/intracutaneous reactivity and sensitisation.

The biocompatibility of the various device materials was assessed from, where available, biocompatibility studies, supplier studies/data, and the published toxicological literature, as well as considerations regarding chemical structure, technical design, history of use in medical applications and the device use scenario. A literature-based assessment was particularly important for the (skin) irritation and sensitisation endpoints. Data searches were limited to the bibra TRACE database for those chemicals with relatively well-studied toxicological profiles, while searches were extended to encompass a variety of additional online data sources for the remaining chemicals.

Chemical characterisation is generally inadequate for a literature assessment of cytotoxicity, as this endpoint is not well-reported for the vast majority of chemicals. A series of in vitro cytotoxicity tests on the devices, conducted in compliance with ISO 10993-5, were used to address this endpoint. Bibra critically evaluated the methods of the newly commissioned studies, and supplemented the assessment with relevant historical study data on chemically similar materials.

Overall, the available information supported the conclusion that the devices demonstrated good biocompatibility characteristics in respect of the cytotoxicity, irritation and sensitisation endpoints under the anticipated conditions of use. Further testing, particularly that involving in vivo methods, was not considered justified for the various devices under consideration.