Original Article Effects of a Thermosensitive In Situ Gel Containing Mometasone Furoate on a Rat Allergic Rhinitis Model EbruAltuntas¸ 1 , Gu ¨ lgu ¨n Yener 1 , Remzi Do gan 2 , Fadlullah Aksoy 2 , Mehmet S¸erif Aydın 3 , and Ersin Karatas¸ 4 Abstract Background: Mometasone furoate, one of the second generation intranasal corticosteroids, is currently used in suspension form due to its poor solubility. However, this is not favorable for nasal application because of the rapid elimination of the instilled drug from the nasal cavity by mucociliary clearance and delayed onset of action due to the slow dissolution of drug in suspension. Objective: The aim of this study was to determine the antiallergic effects of mucoadhesive thermosensitive in situ gel containing mometasone furoate that we developed previously to prolong the contact between the drug and nasal mucosa and to prevent drainage of the formulation in an ovalbumin-induced rat model of allergic rhinitis. Methods: An experimental allergic rhinitis model was developed in female Wistar albino rats by intraperitoneal injection of ovalbumin every 2 days for 14 days followed by its repeated intranasal instillation for 7 consecutive days. Intranasal instil- lation of ovalbumin was continued every other day for 14 days. Mometasone furoate in situ gel (5 lg/10 ml), mometasone furoate suspension (5 lg/10 ml), and physiological saline (10 ml) were administered into the bilateral nasal cavities from day 22 to day 35. Antiallergic effects were evaluated through histopathological evaluation, analysis of ovalbumin-specific serum immunoglobulin E, and a symptom score. Results: Mometasone furoate in situ gel significantly decreased the nasal symptoms and ovalbumin-specific serum immu- noglobulin E level as compared with mometasone furoate suspension and physiological saline. Additionally, inflammatory histological symptoms such as mucosal edema, vascular dilatation, eosinophil infiltration, and loss of cilia within the nasal mucosa of allergic rhinitis model rats were remarkably improved with the treatment of mometasone furoate in situ gel. Conclusion: These results suggest that mometasone furoate in situ gel has a better therapeutic potential for the treatment of allergic rhinitis compared to mometasone furoate suspension. Keywords thermosensitive, in situ gel, mucoadhesive, allergic rhinitis, mometasone furoate, intranasal corticosteroids, suspension, rat model, ovalbumin, immunoglobulin, histopathological evaluation Introduction Allergic rhinitis (AR) is the most common immunoglobulin (Ig)E-mediated inflammatory disease seen in children, adults, and adolescents. 1,2 Intranasal corticosteroids (INCs) are considered the most effective and first choice option for the treatment of AR so far. 1 Mometasone furo- ate (MF) is one of a new generation of INCs which is topically effective with high affinity to glucocorticoid recep- tors and low systemic absorption. 1,3 Nasal sprays contain- ing MF are presented as suspension in the market because of the poor water solubility. Due to the slow dissolution of 1 Department of Pharmaceutical Technology, Faculty of Pharmacy, Istanbul University, Fatih, Istanbul, Turkey 2 Department of Otorhinolaryngology, Bezmialem Vakif University, Fatih, Istanbul, Turkey 3 Medipol Regenerative and Restorative Medicine Research Center, Istanbul Medipol University, Beykoz, Istanbul, Turkey 4 Department of Molecular Biology and Genetics, Gebze Technical University Cayirova/Kocaeli, Turkey Corresponding Author: Ebru Altuntas ¸, Department of Pharmaceutical Technology, Faculty of Pharmacy, Istanbul University, Fatih 34116, Istanbul, Turkey. Email: ebru.altuntas@istanbul.edu.tr American Journal of Rhinology & Allergy 0(0) 1–7 ! The Author(s) 2018 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1945892418764951 journals.sagepub.com/home/ajr