Penetration enhancers and mucoadhesives in liquid nasal spray formulations

For many years, the nasal route of administration has been used very successfully for the non-invasive delivery of small molecule drugs. The anatomy and physiology of the nasal cavity have been exploited to deliver 1) locally acting medications, to combat ailments such as seasonal and year-round allergies, 2) systemically delivered drugs, via the highly vascularized turbinates (e.g., migraine treatments), and 3) drugs delivered directly to the central nervous system (nose-to-brain delivery), via the olfactory and trigeminal nerves (e.g., seizure treatments). Some commercially available liquid nasal spray formulations include excipients that can act as penetration enhancers or mucoadhesives, and may thereby provide the benefit of increasing contact/residence time in the nasal cavity or increasing absorption of drug molecules by enhancing permeability through nasal mucosal membranes. As liquid nasal sprays are now being developed to expand their use from traditional small molecule drug delivery systems to delivery of biologics and as a prophylaxis for respiratory diseases (including coronavirus treatments), the inclusion of penetration enhancers and mucoadhesives may become more important.