Biological evaluation of an ultrasound gel for an invasive application within risk management

SOT 2024 -- The purpose of this study was to define an approach within risk management to determine acceptable safety limits of an ultrasound gel for invasive applications based on the results of a systemic toxicity study using a wide range of concentrations of the gel. Ultrasound gels are composed largely of water and polymers and are utilized in ultrasound-based diagnostic medical imaging procedures. Typically, ultrasound gels find extensive use in noninvasive diagnostic procedures. Classified as a medical device, the regulatory requirements of biological evaluation for such procedures include safety data from a simple panel of tests that include cytotoxicity, irritation and sensitization tests to demonstrate their biocompatibility. One of the commonly used ultrasound gels, tested for these end points, showed it to be non-cytotoxic in vitro and non-irritating and non-sensitizing in vivo. However, extension of application of the ultrasound gel to an invasive procedure, such as ultrasound-guided tissue biopsy, requires more comprehensive biocompatibility evaluation. The risk profile subsequently expanded as the contact of the gel material may now entail muscle, bone and potentially even result in the accidental exposure of circulating blood. The additional biological evaluation endpoints required for such invasive diagnostic procedure includes systemic toxicity, pyrogenicity and hemocompatibility. Whereas no pyrogenicity potential of the gel was evident in our studies, significant systemic toxicity was noted in vivo, which was addressed within risk management approach.