Challenge

During biocompatibility testing for a long-term implantable device, the guinea pig maximization test (GPMT) revealed a positive sensitization response, but only in sesame oil extracts, not in saline.

Given that sesame oil was a non-clinical extraction medium for the device representing a worst-case scenario, the result raised concerns with the regulatory team about potential allergenic risks, despite no supporting evidence from other biological endpoints.

‍

Chemva’s Solution

Chemva led a contextual data evaluation to assess whether the positive result represented a real clinical risk.

First, we examined the clinical use scenario: the implant is not exposed to lipid-like environments such as sesame oil in vivo, meaning the extraction vehicle was not reflective of physiological conditions. Second, we compared this with the saline extract, which showed no sensitization response, indicating no leachable compounds of concern under clinically relevant conditions.

Furthermore, we integrated results from implantation studies, which showed no adverse tissue response, no evidence of local immune reaction, and consistent tissue healing. This weight-of-evidence approach, aligned with ISO 10993-1 and incorporated into the Biological Evaluation Report (BER), demonstrated that the device posed no meaningful sensitization risk in its intended use.

‍

Impact Delivered

By interpreting the sensitization result in context and pairing it with in-vivo implantation data, Chemva provided a strong, science-backed justification to regulatory authorities.
The result: the product's biological safety profile was accepted without additional testing or reformulation, helping our partner maintain development timelines and avoid costly delays.