Ethanol-Based Proliposomes Incorporating Dexamethasone for The Treatment of COVID-19 Acute Respiratory Distress Syndrome (ARDS) Using Medical Nebulizers

Abstract

Background/Objective: Systemic dexamethasone has demonstrated mortality reduction in COVID-19-related acute respiratory distress syndrome (ARDS). The aim of this study is to use ethanol-based proliposome technology to formulate inhalable liposomes encapsulating dexamethasone for localized anti-inflammatory effect in the lung. Methods: Ethanol-based proliposomes were prepared using equimolar ratios of cholesterol and one of three phospholipids: soya-phosphatidylcholine(SPC), hydrogenated SPC(HSPC), or dipalmitoyl-phosphatidylcholine(DPPC). Hydration of proliposomes was followed by probe-sonication to generate small unilamellar vesicles (SUVs), then followed by the determination of particle size, zeta-potential, entrapment efficiency, and drug release. Aerosol characterization studies were performed using three different nebulizers (air-jet, ultrasonic, and mesh) delivered to a two-stage impinger. Finally, cytokine release was measured in peripheral blood mononuclear cells stimulated with lipopolysaccharide and treated with the formulation. Results: The prepared SUVs had particle size <100 nm, polydispersity index (PDI) <0.3, and slightly negative zeta-potential. SPC liposomes had significantly (pvalue< 0.05) lower particle size and PDI compared to HSPC and DPPC liposomes, and entrapped significantly more dexamethasone (p-value<0.05). The air-jet nebulizer was the superior nebulizer in terms of mass, drug, and lipid output and fine particle fraction, and was the least physically disruptive to liposomes. All three formulations were successfully delivered using the air-jet nebulizer; however, SPC liposomes had significantly higher drug output rate, respirable dose, and underwent less aggregation. Cytokine release studies demonstrated that liposomal dexamethasone suppressed cytokine release in a manner superior to free dexamethasone. Conclusion: SUVs with small particle size and low PDI were successfully prepared and delivered using different nebulizers. Of the three investigated formulations, SPC liposomes delivered using the air-jet nebulizer are the most promising for further development. Future studies will be dedicated to scaling up this formulation and testing it using in vivo models of acute lung injury.