Hydroxypropyl Methylcellulose-Based Nasal Sprays Effectively Inhibit In Vitro SARS-CoV-2 Infection and Spread

Abstract

The ongoing coronavirus disease (COVID-19) pandemic has required a variety of non-medical interventions to limit the transmission of the causative agent, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). One such option is over-the-counter nasal sprays that aim to block virus entry and transmission within the nasal cavity. In this study, we assessed the ability of three hydroxypropyl methylcellulose (HPMC)-based powder nasal sprays, produced by Nasaleze, to inhibit SARS-CoV-2 infection and release in vitro. Upon application, the HPMC powder forms a gel-like matrix within the nasal cavity—a process we recapitulated in cell culture. We found that virus release from cells previously infected with SARS-CoV-2 was inhibited by the gel matrix product in a dose-dependent manner, with virus levels reduced by >99.99% over a 72 h period at a dose of 6.4 mg/3.5 cm2. We also show that the pre-treatment of cells with product inhibited SARS-CoV-2 infection, independent of the virus variant. The primary mechanism of action appears to be via the formation of a physical, passive barrier. However, the addition of wild garlic provided additional direct antiviral properties in some formulations. We conclude that HPMC-based nasal sprays may offer an additional component to strategies to limit the spread of respiratory viruses, including SARS-CoV-2.

Evaluating the efficacy and safety of a novel prophylactic nasal spray in the prevention of SARS-CoV-2 infection: A multi-centre, double blind, placebo-controlled, randomised trial.

“…To date, several in-vitro and animal studies have investigated the use of nasal spray formulations in the post-exposure prophylaxis of SARS-CoV-19 infection 17 , 18 , 19 . A wide range of substances aimed at blocking viral entry to the host have been proposed for nasal administration and are currently being trialled in humans including quinine, nitric oxide, and povidine iodine [20] .…”

Improving Nasal Protection for Preventing SARS-CoV-2 Infection

“…Bentley and Stanton investigated the effectiveness of three different hydroxypropyl methylcellulose (HPMC)-based nasal sprays (93% HPMC, 2% peppermint powder and 5% European wild garlic powder; 95% HPMC, 2% peppermint powder and 3% allicin powder; 98.5% HPMC and 1.5% peppermint powder) to prevent in vitro SARS-CoV-2 infection [ 45 ]. Pre-treatment of ACE2-expressing VeroE6 cells with each of these compounds at a concentration of 6.4 mg/3.5 cm 2 was effective to prevent SARS-CoV-2 infection, but was also associated with almost total inhibition of virus release from infected cells.…”

Interferon α-2b spray shortened viral shedding time of SARS-CoV-2 Omicron variant: An open prospective cohort study

“…Similarly, another study identified that Omicron variant replicates more rapidly in the respiratory tract than all other SARS-CoV-2 variants, but less efficiently in the lungs, which may explain the reduced severity of Omicron that is now being reported in epidemiological studies (19). As the highest viral loads are detectable in the upper respiratory tract, reducing infectious viruses in the nasopharynx could lower viral shedding and, consequently, transmission by infected individuals (20).…”