In this episode, our hosts are joined by Dr. Joe Carraway, co-author of the new research paper, “The suitability of reconstructed human epidermis models for medical device irritation assessment: A comparison of In Vitro and In Vivo testing results,” which discusses in vitro irritation assays and their viability for medical device testing. The three Rs in this type of experimentation, which stand for Replacement, Reduction and Refinement, are a concept always considered for new test development. In vitro irritation is one of the latest to reach the normative text of the ISO standards and manufactures and laboratories will need to be prepared to evaluate and utilize this test method. This episode provides in-depth  details regarding the timing of the standard, the viability and accuracy of the test method and opportunities and challenges for laboratories and manufacturers related to the standard.

“The standards were written in such a way that it was still an option, and with the release of this new part 23… it essentially mandates what you really need to be doing, if you need to test for irritation {…} if you’ve determined that the next step says you do an in vitro model before going into an in vivo model.” Dr. Carraway

“The concern with predictive assays is you don’t want to have false negatives. You can live with false positives because you are typically going to do further testing to confirm those.” Dr. Carraway

“If you have a positive response, one of the approaches is to look at in vivo testing. Here, it’s a point to point comparison of irritation.” Don Pohl

Discussion points include:

• When will an in vitro method be expected for irritation?
• What was the methodology of this comparison study?
• How does the in vitro method compare against the primary skin and intracutaneous study?
• What are some challenges of the in vitro study?
• What should manufacturers be doing now to prepare for the new ISO 10993-23