In vitro Inactivation of SARS-Cov-2 by Povidone-Iodine In situ Gel FormingSolution

Background: Povidone Iodine (PVP-I) nasal solutions are effective against the SARS-CoV-2 virus, but are cleared rapidly from the nasal cavity, limiting its use. PVP-I gel forming solutions can circumvent this problem due to their higher viscosity and prolonged clearing time. Objective: Characterize the in vitro virucidal activity of long-acting PVP-I compositions developed using an in situ gel forming technology against the SARS-CoV-2 virus and test its safety using a rat model. Methods: We tested different dilutions of the PVP-I gel forming solution– full concentration, 90%, 50%, 28% and 9% of the original formulation concentration – at varying exposure times to assess virucidal activity against SARSCoV- 2 in VERO76 cells infected. Virucidal activity was recorded as the reduction of virus in formulation-treated test wells compared to virus controls as a log reduction value. We conducted a 28-day toxicity study using Sprague Dawley CD® IGS rats to determine the potential delayed toxicity of a PVP-I formulation. Results: The PVP-I gel-forming nasal spray rapidly inactivated SARS-CoV-2, inhibiting the viral infection of VERO76 cells. No toxicity was observed for the PVP-I formulations. Significant inactivation was noted with preincubation of the virus with this PVP-I formulation at the lowest concentrations tested. No delayed toxicity was observed in our animal model. Conclusions: PVP-I gel forming formulations inactivate SARS-CoV-2 in vitro within 30 seconds of exposure, with increasing effects seen at higher exposure times. These formulations could prove useful in a clinical setting for managing SARS-CoV-2 infected patients.