Antimicrobial mouthwashes as a preventive measure against Covid-19 - a comparative analysis of their effects on human chondrocytes and cartilage

Objectives: Antimicrobial mouthwashes are recommended as a preventive measure against SARS-Cov-2. This study compared the cytotoxicity of octenidine dihydrochloride and chlorhexidine gluconate at different concentrations on human chondrocytes and cartilage. Materials and methods Primary cultures of normal adult human articular chondrocytes were exposed to octenidine dihydrochloride (0.001562%, 0.003125%, 0.00625%, 0.0125%, 0.025%, 0.05%, and 0.1%), chlorhexidine gluconate (0.003125%, 0.00625%, 0.0125%, 0.025%, 0.05%, 0.1%, and 0.2%), and control (Dulbecco's modified Eagle medium or phosphate buffered saline) for 30 seconds. Normal human articular cartilage explants were exposed to octenidine dihydrochloride (0.1% versus control) and chlorhexidine gluconate (0.1% versus control) for 30 seconds. The viability of human articular chondrocytes was measured by Trypan blue staining, Cell Proliferation Reagent WST-1, and Live/Dead staining. The proliferation of human articular chondrocytes was measured using the Cell Proliferation Reagent WST-1. The viability of human articular cartilage explants was measured by using Live/Dead staining. Results Octenidine dihydrochloride and chlorhexidine gluconate exposure decreased cell viability and proliferation in a dose-dependent manner in primary adult human normal articular chondrocytes. Octenidine dihydrochloride and chlorhexidine gluconate exposure decreased cell viability in human articular cartilage explant cultures. Conclusion The degree of toxicity varied between octenidine dihydrochloride and chlorhexidine gluconate, with chlorhexidine gluconate being less toxic than octenidine dihydrochloride at the same concentration. Additionally, both octenidine dihydrochloride and chlorhexidine gluconate evaluation had cytotoxic effects on human articular cartilage. Therefore, dosing for the antimicrobial mouthwash ingredients administration would ideally be determined to remain below IC50. Clinical relevance Our study supports the in vitro safety of antimicrobial mouthwashes on articular chondrocytes. The data do not suggest to advise such antimicrobial mouthwashes as a general Covid prophylaxis.