Astodrimer sodium antiviral nasal spray for reducing respiratory infections is safe and well tolerated in a randomized controlled trial.

Astodrimer sodium is a dendrimer molecule with antiviral and virucidal activity against SARS-CoV-2 and other respiratory viruses in vitro, and has previously been shown to be safe and well tolerated, and not systemically absorbed, when applied to the vaginal mucosa. To investigate its potential utility as a topical antiviral, astodrimer sodium has been reformulated for application to the nasal mucosa to help reduce viral load before or after exposure to respiratory infection. The current investigation assessed the safety, tolerability and absorption of astodrimer sodium 1% antiviral nasal spray. This was a single-centre, double-blinded, randomized, placebo-controlled, exploratory clinical investigation. Forty healthy volunteers aged 18 to 65 years with no clinically significant nasal cavity examination findings were randomized 3:1 to astodrimer sodium nasal spray (N = 30) or placebo (N = 10) at an Australian clinical trials facility. An initial cohort of participants (N = 12 astodrimer, N = 4 placebo) received a single application (one spray per nostril) to assess any acute effects, followed by a washout period, before self-administering the spray four times daily for 14 days to represent an intensive application schedule. Extent of absorption of astodrimer sodium via the nasal mucosa was also assessed in this cohort. A second cohort of participants (N = 18 astodrimer, N = 6 placebo) self-administered the spray four times daily for 14 days. The primary endpoint was safety, measured by frequency and severity of treatment emergent adverse events (TEAEs), including clinically significant nasal cavity examination findings, in the safety population (all participants randomized who administered any spray). Participants were randomized between 6 January 2021 and 29 March 2021. TEAEs occurred in 8/10 (80%) participants in the placebo arm and 19/30 (63.3%) participants in the astodrimer sodium arm; all were of mild intensity. TEAEs considered potentially related to study product occurred in 5/10 (50%) participants receiving placebo and 10/30 (33.3%) of participants receiving astodrimer sodium. No participants experienced serious AEs, or TEAEs leading to withdrawal from the study. No systemic absorption of astodrimer sodium via the nasal mucosa was detected. Astodrimer sodium nasal spray was well tolerated and is a promising innovation warranting further investigation for nasal administration to potentially reduce infection and spread of community acquired respiratory virus infections.Trial Registration: ACTRN12620001371987, first registered 22-12-2020 (Australia New Zealand Clinical Trials Registry, https://anzctr.org.au/ ).

Protective Effects of Astodrimer Sodium 1% Nasal Spray Formulation against SARS-CoV-2 Nasal Challenge in K18-hACE2 Mice.

Strategies to combat COVID-19 require multiple ways to protect vulnerable people from infection. SARS-CoV-2 is an airborne pathogen and the nasal cavity is a primary target of infection. The K18-hACE2 mouse model was used to investigate the anti-SARS-CoV-2 efficacy of astodrimer sodium formulated in a mucoadhesive nasal spray. Animals received astodrimer sodium 1% nasal spray or PBS intranasally, or intranasally and intratracheally, for 7 days, and they were infected intranasally with SARS-CoV-2 after the first product administration on Day 0. Another group was infected intranasally with SARS-CoV-2 that had been pre-incubated with astodrimer sodium 1% nasal spray or PBS for 60 min before the neutralisation of test product activity. Astodrimer sodium 1% significantly reduced the viral genome copies (>99.9%) and the infectious virus (~95%) in the lung and trachea vs. PBS. The pre-incubation of SARS-CoV-2 with astodrimer sodium 1% resulted in a significant reduction in the viral genome copies (>99.9%) and the infectious virus (>99%) in the lung and trachea, and the infectious virus was not detected in the brain or liver. Astodrimer sodium 1% resulted in a significant reduction of viral genome copies in nasal secretions vs. PBS on Day 7 post-infection. A reduction in the viral shedding from the nasal cavity may result in lower virus transmission rates. Viraemia was low or undetectable in animals treated with astodrimer sodium 1% or infected with treated virus, correlating with the lack of detectable viral replication in the liver. Similarly, low virus replication in the nasal cavity after treatment with astodrimer sodium 1% potentially protected the brain from infection. Astodrimer sodium 1% significantly reduced the pro-inflammatory cytokines IL-6, IL-1α, IL-1ß, TNFα and TGFß and the chemokine MCP-1 in the serum, lung and trachea vs. PBS. Astodrimer sodium 1% nasal spray blocked or reduced SARS-CoV-2 replication and its sequelae in K18-hACE2 mice. These data indicate a potential role for the product in preventing SARS-CoV-2 infection or for reducing the severity of COVID-19.

Virucidal and antiviral activity of astodrimer sodium against SARS-CoV-2 in vitro.

An effective response to the ongoing coronavirus disease (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will involve a range of complementary preventive modalities. The current studies were conducted to evaluate the in vitro SARS-CoV-2 antiviral and virucidal (irreversible) activity of astodrimer sodium, a dendrimer with broad spectrum antimicrobial activity, including against enveloped viruses in in vitro and in vivo models, that is marketed for antiviral and antibacterial applications. We report that astodrimer sodium inhibits replication of SARS-CoV-2 in Vero E6 and Calu-3 cells, with 50% effective concentrations (EC50) for i) reducing virus-induced cytopathic effect of 0.002-0.012 mg/mL in Vero E6 cells, and ii) infectious virus release by plaque assay of 0.019-0.032 mg/mL in Vero E6 cells and 0.030-0.037 mg/mL in Calu-3 cells. The selectivity index (SI) in these assays was as high as 2197. Astodrimer sodium was also virucidal, irreversibly reducing SARS-CoV-2 infectivity by >99.9% (>3 log10) within 1 min of exposure, and up to >99.999% (>5 log10) shown at astodrimer sodium concentrations of 10-30 mg/mL in Vero E6 and Calu-3 cell lines. Astodrimer sodium also inhibited infection in a primary human airway epithelial cell line. The data were similar for all investigations and were consistent with the potent antiviral and virucidal activity of astodrimer sodium being due to irreversible inhibition of virus-host cell interactions, as previously demonstrated for other viruses. Further studies will confirm if astodrimer sodium binds to SARS-CoV-2 spike protein and physically blocks initial attachment of the virus to the host cell. Given the in vitro effectiveness and significantly high SI, astodrimer sodium warrants further investigation for potential as a topically administered agent for SARS-CoV-2 therapeutic applications.