Site-Specific Microparticle Inhalation Therapy: A New Approach to Nasopharyngeal Symptoms.

Background/Objectives: Inhalable Microparticles (IMPs) are part of a currently invading field of medicine. In fact, the anatomical district of Rhinopharynx represents a bed for many different pathologies and infections, where the dimension of drug aerosol Microparticles (MPs) represents a discriminating factor to success therapy. The aims of the present work are to demonstrate the efficacy of a new device and its aerosol reproducibility in the nebulization of suspensions to be deposited in the retropharynx. Materials and Methods: The Low-Angle Laser Light Scattering (LALLS) method was used to evaluate both the dimension and distribution of MPs. Six different APIs, used usually in Rhinopharynx pathology, were compared in order to investigate the dimension of MP emissions using four different devices. The results of a retrospective study including 74 subjects treated with standard therapy (ST) and the inhalation of nebulized Sobrerol (NS) were performed. Data regarding the persistence of clinical symptoms (i.e., cough and nasal constipation) were acquired. Results: No significant statistical differences among all the products tested (p > 0.05) were found. One device, Rinubes, demonstrated efficacy and robustness in the fine nebulization of all the pharmaceutical products analyzed. Rinubes delivered an aerosol cloud with significantly lower MMD (66.3 µm) than Mad Nasal and Spray-sol (142.1 and 116.0 µm, respectively), which would allow a higher fraction of drugs to be deposited in the retropharynx. The retrospective clinical study revealed that NS treatment showed higher odds of cough resolution (OR 9.18; p < 0.001) with respect to control ST and showed higher odds of nasal symptom resolution (OR 6.7; p = 0.043). Conclusions: Improved techniques for the administration of inhalable MPs (INPAD) represent significant progress in overcoming the biological and the anatomical barriers in controlling drug release at a specific site. The challenges of nasopharyngeal pathologies offer promising opportunities for the development of non-invasive drug delivery.