Pirfenidone-loaded liposomes for lung targeting: preparation and in vitro/in vivo evaluation

BACKGROUND: The purpose of this study was to develop novel pirfenidone (PFD)-loaded liposomes for targeting to the lung. METHODS: The liposomes were prepared by the film hydration method, and their in vitro/vivo characteristics were evaluated. RESULTS: The PFD liposomes appeared visually as green to yellowish suspensions and were spherical in shape. The particle size was 582.3±21.6 nm and the entrapment efficiency was relatively high (87.2%±5.7%). The liposomes showed typical sustained and prolonged drug-release behavior in vitro and fitted well with the Weibull distribution equation. The relatively slower time taken to reach a minimal plasma PFD concentration in vivo suggests that PFD liposomes have a sustained-release profile, which is consistent with the results of the in vitro release study. The PFD liposomes showed the largest area under the curve for the lung. The high distribution of PFD achieved in the lungs using this liposomal formulation may be explained by physical entrapment of the liposomes in the vascular network of the lung. Histopathological results indicated that liposomal PFD could alleviate pathological injury in lung tissue. CONCLUSION: This liposomal formulation can enable sustained release of PFD and increase targeting to the lung.