Polymeric nanoparticles (NPs) have received much attention as promising carrier systems in lung cancer and brain metastases.

Here, for the first time, we investigated the feasibility of using inhaled cholesterol-PEG co-modified poly (n-butyl) cyanoacrylate NPs (CLS-PEG NPs) of docetaxel (DTX) for sustained pulmonary drug delivery in cancer metastasis.

Spray-dried or freeze-dried NPs yielded sustained drug release in vitro. In vitro inhalation evaluation data indicated that the inhalation formulation had better inhalability. Compared with intravenous (IV) administration, pharmacokinetic data suggested that the inhalation formulation prolonged plasma concentration of DTX for greater than 24 h and is more quickly and completely absorbed into the rat lung after intratracheal (IT) administration. Furthermore, freeze-dried powders were found to increase the t_1/2 and area under curve (AUC) by 2.3 and 6.5 fold compared to the free drug after IT administration, and spray-dried powders were found to increase the t_1/2 and AUC by 3.4 and 8.8 fold, respectively. After pulmonary administration of the inhalation formulation, DTX appeared to prolong the pulmonary absorption time. In addition, the inhalation formulation was distributed to the brain in a sustained release manner.

These experimental results demonstrated that freeze- and spray-dried powders have the potential for pulmonary sustained release, and they also have the potential to be used as a novel treatment for the delivery of drugs that pass through the air–blood barrier and enter the brain and are efficient carriers for the treatment of brain metastasis.