Nasal and pulmonary routes of drug delivery

Nasal and pulmonary drug delivery are attractive routes for the administration of a growing number of drugs for topical and systemic treatment as well as for prevention by vaccines. This is of particular interest for drugs with poor bioavailability, as the gastrointestinal passage and hepatic first pass effect can be avoided. The development of drugs, vehicles, and devices made substantial progress. The drug delivery research is focused on transmucosal absorption enhancers such as surfactants, enzyme inhibitors, biopolymers, tight junction modulators, cyclodextrins, and gelling systems and on nasal and pulmonary carrier systems like nanoparticles, microspheres, nano- or microemulsions, and liposomes. Many approaches are still in early development and need further investigation. The trend for devices is going to nasal dry powder inhalers and smart pulmonary nebulizers. A new research area includes inhalable vaccines, biological drugs, and coronavirus treatments.