Intranasal administration of drugs.

Objective: To investigate how nasally applied substances distribute in the nose depending on the form of application.

Design: Observer-blinded study.

Setting: University hospital research unit.

Participants: Fifteen healthy volunteers aged 22 to 32 years.

Interventions: Forms of application included (1) nasal drops applied with a pipette, (2) nasal spray, and (3) a system producing squirts. Blue food dye was used to visualize the intranasal distribution of the liquid. The investigation was performed using nasal endoscopy.

Main Outcome Measure: Intranasal distribution of the dye was judged by 2 independent observers blinded to the applicator system used.

Results: The nasal drops predominantly reached the nasal floor. The nasal spray was widely distributed in the nasal mucosa; however, most of it was intercepted by the middle turbinate and did not reach the olfactory cleft effectively. Using the squirt system, the olfactory cleft was reached in most participants.

Conclusions: Previous failure of therapy with locally applied drugs in the case of sinonasal smell disorders may be partly due to the fact that the drugs did not reach the olfactory cleft when using traditional forms of application (ie, sprays). However, using an applicator producing squirts seems likely to present the drugs more effectively to the olfactory epithelium. Thus, it may be hypothesized that therapy could be more effective using a squirt system.