The nasal route can be used both for local treatment of disease (e.g., allergic rhinitis and nasal congestion) and to administer therapeutic agents for systemic absorption and action.
As a route for systemic drug delivery, the nose is readily accessible and is a convenient and noninvasive way to administer drugs. The underlying epithelium is highly vascularized, and blood passes from the nose directly into the systemic circulation. As a result, nasally administered drugs will be readily absorbed into the bloodstream, avoiding first pass metabolism and providing rapid therapeutic effect.
Nasal administration is particularly attractive when rapid treatment is required—for critical medical conditions and where rapid symptom relief is a key aim, for example breakthrough cancer pain. Additionally, nasal administration avoids exposure to digestive enzymes, a problem when attempting to administer peptide and protein drugs orally, and offers the potential for injection-free administration of these therapeutic agents.
The nasal route is particularly attractive for vaccine administration. The nose has its own nasal-associated lymphoid tissue that is accessible for immunization. Nasal immunization has significant advantages over conventional parenteral delivery of vaccines, as both systemic and mucosal immune responses are generated. Nasal vaccination can obviate the need for needles and syringes, encouraging greater public compliance, and, at times of a pandemic, is well-suited to rapid mass vaccination programs.
Although other noninjection delivery routes claim similar advantages, nasal administration stands out for many reasons. Nasal absorption is faster, more complete, and significantly more convenient compared to oral transmucosal (buccal/sublingual) administration; compared to pulmonary delivery, nasal delivery is simpler, is independent of patient technique, and requires less expensive and complex delivery devices.