RESPIRABLE POWDER CONTAINING CYCLOSPORINE A LOADED LIPOSOMES AS IMMUNOSUPPRESSIVE AGENT SUITABLE FOR LUNG TRANSPLANT REJECTION AND THE CONTAINMENT OF SEVERE LUNG INFLAMMATION

ABSTRACT

The work led to the formulation of a powder of calcium phosphate coated liposomes containing cyclosporine A (CsA). The formulation was designed to reduce the dose of CsA to be administered following lung transplantation. Potentially this formulation can be used also to contain the inflammatory process due to SARS-CoV-2. Calcium phosphate (CaP) is a material found in bones and teeth and considered non-toxic and biocompatible and this coating could reduce the recognition by alveolar macrophages and increase the cell uptake. Moreover, CaP is insoluble at physiological pH (7.4), while it solubilizes easily at pH below 5. This could favor drug release in the cell after pinocytosis and in inflamed tissues, while reducing drug release at physiological pH [1]. The liposomes produced were evaluated in terms of size, surface charge and drug loading. The presence of the CaP coating was verified by calcium titration, variation of the zeta potential and by cryogenic transmission electron microscopy (cryo-TEM). The highest loading was obtained in the formulation containing CsA at 7% (w/w). Cholesterol was added to liposomes at two different concentrations in order to improve the stability of the nanostructure and reduce the drug leakage. However, cholesterol did not bring any improvement to the formulation. The inhalation powder produced by spray drying with the best aerosolization performance (fine particle fraction of coated liposomes powder 33.69 - 1.6% and 50.50- 0.6% for the uncoated liposomes powder) was obtained using a 13 weight ratio between liposomes and excipients using mannitol as bulking agent and 15% L-leucine. Key Message This work aimed to develop a respirable dry powder for inhalation containing CsA for the local treatment of lung immune diseases. CsA was efficiently loaded into CaP-coated liposomes and transformed into a respirable powder by spray-drying. The inhaled immunosuppressive product would offer multiple advantages related to drug deposition at the target site. Furthermore, the coating of the liposomes governs the release of the drug which will occur only at only at biological acidic conditions.