In Vitro Development of Local Antiviral Formulations with Potent Virucidal Activity Against SARS-CoV-2 and Influenza Viruses.

This study investigates the in vitro antiviral potential of D-limonene (DLM), monolaurin (ML), and cetylpyridinium chloride (CPC) in formulations targeting SARS-CoV-2 and influenza viruses. The aim was to develop oral and nasal formulations with optimized concentrations of these active ingredients to evaluate their efficacy, safety, and stability. Oral (formulation D) and nasal (formulation E) products were developed using specific concentrations of DLM (0.2-0.3% /), ML (0.1-0.2% /), and CPC (0.05-0.075% /). In vitro virucidal activity assays were conducted to assess the antiviral efficacy of the formulations against SARS-CoV-2 and influenza viruses. Stability testing was also performed under various storage conditions. Formulation D (0.3% / DLM, 0.2% / ML, 0.05% / CPC, and 1.5% / Cremophor RH40) demonstrated a 3.875 ± 0.1021 log reduction and 99.99 ± 0.0032% efficacy against SARS-CoV-2 within 120 s. Formulation E (0.2% / DLM, 0.05% / CPC, and 0.75% / Cremophor RH40) showed a 2.9063 ± 0.1197 log reduction and 99.87 ± 0.0369% efficacy against SARS-CoV-2. Both formulations achieved >99.99% efficacy and log reductions exceeding 4.000 against various influenza strains. Stability testing confirmed optimal performance at 4 °C with no microbial contamination. The findings suggest that both formulations exhibit broad-spectrum antiviral activity against SARS-CoV-2 and influenza viruses in vitro. These results support their potential for further clinical evaluations and therapeutic applications, particularly in oral and nasal spray formulations.