In vitro Comparison of Safety and Efficacy of Diluted Isotonic Seawater and Electrodialyzed Seawater for Nasal Hygiene

Background Nasal irrigation is often used for managing sinonasal conditions and maintaining nasal hygiene, which is critical to overall nasal health and to provide protection against airborne contaminants and pathogens. However, studies comparing efficacies of different solutions are needed. Purpose This in vitro study evaluated the ionic balance of an isotonic diluted seawater solution (Sterimar Nasal Hygiene, SNH) and its safety and efficacy for regular nasal hygiene in comparison to electrodialyzed seawater (EDS). Materials and methods Ionic balance of SNH, EDS and pure seawater was measured by mass spectrometry and chromatography to be compared to the ionic balance of human plasma as reported in the literature. Safety was measured through cytotoxicity (lactate dehydrogenase release) and pro-inflammation (interleukin-8 secretion) assays using a 3D-reconstituted human nasal epithelium model. For efficacy, adenosine 5'-triphosphate (ATP) release assays, and histological (alcian blue) and immunohistochemical (aquaporin 3) stainings were performed on tissues under hypotonic challenge where saline solution was used as the negative control. Results Compared to EDS, the ionic balance of SNH was more similar to human plasma and pure seawater. SNH reduced hypotonic stress-associated ATP release and maintained tissue morphology more effectively and lastingly compared to EDS. Both solutions were safe to use on nasal epithelium, as neither of them caused cytotoxicity or induced (pro-) inflammation. Conclusion In comparison to EDS, this study confirms the safety and efficacy of SNH in maintaining good nasal hygiene consistent with its benefits reported in clinical trials.