Micro and nano-carriers-based pulmonary drug delivery system: Their current updates, challenges, and limitations – A review

The lung is an attractive target for drug delivery because of the ease of non-invasive administration via inhalation, bypassing metabolism in the liver, direct delivery to the respiratory system for treatment of respiratory diseases, and a large surface area for drug absorption. Nanocarrier systems offer several benefits for pulmonary drug delivery, including uniform drug distribution among alveoli, improved drug solubility, sustained drug release, which reduces the dosing frequency and enhances patient compliance, and potential for cell drug internalization. Nanomedicine is also being utilized to combat emerging infectious illnesses like SARS-CoV, SARS-CoV-2, MERS-CoV, and influenza A/H1N1. This review gives a quick rundown of pulmonary diseases caused by infectious agents such as bacterial, viral, and biological roadblocks that prevent effective treatment of recalcitrant respiratory tract infections. We emphasized and summarized recent efforts to combat these infections using novel inhaled formulation-mediated pulmonary delivery strategies like nanocarriers such as liposomes, polymeric nanoparticles, and SLNs. In addition, we also reviewed the latest findings and advancements regarding the development of inhalable novel formulations that circumvent biological barriers and boost drug bioavailability.