Nasal Emulgel's Role in Preventing Coronavirus Infection.

Background/Objectives: Coronaviruses (CoVs) are a large family of respiratory viruses that cause respiratory illnesses ranging from mild colds to severe diseases such as severe acute respiratory syndrome and pandemics. The nasal cavity is a primary site for CoV entry and transmission. The study aimed to prepare a novel mucoadhesive emulgel specifically formulated with simple, safe, and cost-effective excipients to create a barrier on the nasal mucosa that impedes CoV infection. This formulation strategy was specifically designed to enable rapid and straightforward in vivo translation, addressing a critical gap in preventive measures against respiratory viruses. Methods: Three emulgels, containing macadamia oil, Carbopol and different percentages of hydroxypropyl methylcellulose (1, 1.2 and 1.5% (w/v), HPMC), were properly prepared and characterized for mucoadhesion, viscosity, and spreadability. The biological activity against SARS-CoV-2 was evaluated in vitro on infected epithelial cells. Results: The emulgel with 1.2% HPMC demonstrated optimal physicochemical properties (mucoadhesion: 342 ± 9 mN/cm2; viscosity: 1080 ± 83 cp; spreadability: 7.27 ± 0.06 cm) suitable for nasal application. Importantly, in vitro biological assays demonstrated that this emulgel significantly inhibits SARS-CoV-2 infection in epithelial cells, indicating an effective barrier to viral diffusion. Conclusions: By employing readily available, safe, and inexpensive excipients, this novel mucoadhesive emulgel offers a practical, scalable, and rapidly translatable nasal prophylactic approach to prevent early SARS-CoV-2 infection, addressing a critical unmet need in pandemic preparedness.