Development of an Antiviral Ion-Activated In Situ Gel Containing 18β-Glycyrrhetinic Acid: A Promising Alternative Against Respiratory Syncytial Virus

Abstract

The human respiratory syncytial virus (hRSV) poses a serious risk to global public health and is a significant cause of severe lower respiratory infections. There are currently only a few therapies available to treat RSV infections, as well as no RSV vaccinations. Therefore, there is an urgent demand for clinically feasible, safe, and affordable RSV prevention and treatment alternatives. In this study, an ion-activated in situ gel comprising broad-spectrum antiviral 18β-glycyrrhetinic acid (GA) for antiviral action on RSV was developed. In this content, mechanical properties, sprayability, drug content, pH, ex vivo mucoadhesive strength, in vitro drug release pattern, and stability were all examined. Rheological properties were also tested by utilizing in vitro gelation capacity and rheological synergism tests. Finally, the optimized in situ gel's cytotoxic and antiviral activities on RSV cultured in human laryngeal epidermoid carcinoma (HEP-2) cell line were evaluated. In conclusion, the optimized in situ gel prepared with a combination of 0.5%w/w gellan gum and 0.5%w/w sodium carboxymethylcellulose demonstrated good gelation capacity and sprayability (weight deviation between T0 and T14: 0.34%), desired rheological synergism (mucoadhesive force (Fb): 9.53), mechanical characteristics (adhesiveness: 0.300 mJ ± 0.05), ex vivo bioadhesion force (19.67 g ± 1.90), drug content uniformity (RSD%: 0.494), and sustained drug release over period of 168 h (101.57% ± 0.53). The antiviral activity test results showed that the optimized in situ gel had strong anti-HRSV activity (EC50 simultaneous = 0.05 µg/ml, SI = 306; EC50 preinfection = 0.154 µg/ml, SI= 100) which was significantly higher than that of ribavirin (EC50 =4.189 µg/ml; SI= 28) used as a positive control against hRSV. In conclusion, this research has demonstrated the formulation of an effective antiviral nasal spray that has the ability to possess both prophylactic and virucidal activity.