A new approach to the treatment of recurrent aphthous stomatitis with bioadhesive gels containing cyclosporine A solid lipid nanoparticles: in vivo/in vitro examinations

Sinem Yaprak Karavana,¹ Evren Homan Gökçe,¹ Seda Rençber,¹ Seda Özbal,² Çetin Pekçetin,² Pelin Güneri,³ Gökhan Ertan<sup>1

1</sup>Department of Pharmaceutical Technology, Faculty of Pharmacy, Ege University, Bornova-Izmir, ²Department of Histology and Embryology, School of Medicine, Dokuz Eylul University, Inciralti, Izmir, ³Department of Oral Diagnosis and Radiology, Faculty of Dentistry, Ege University, Bornova-Izmir, Turkey

Aim: To develop a suitable buccal bioadhesive gel formulation containing cyclosporine A solid lipid nanoparticles (CsA SLNs) for the treatment of recurrent aphthous stomatitis.
Methods: The suitability of the prepared formulations for buccal application was assessed by means of rheological studies, textural profile analysis, and ex vivo drug-release studies. Plastic flows, typical gel-like spectra, and suitable mechanical properties were obtained from prepared formulations. The retention time was explored in in vivo distribution studies and the effect of the gel containing CsA SLNs on the healing of oral mucosal ulceration was investigated in an animal model. In vivo distribution studies are a very important indicator of the retention time of formulations at the application site.
Results: Distribution studies showed that 64.76% ± 8.35% of the formulation coded "F8+SLN" remained on the buccal mucosa 6 hours after application. For the second part of the in vivo experiments, 36 rabbits were separated into three groups: the first group was treated with the gel formulation without the active agent; the second group with the gel formulation containing CsA SLNs; and the third group, used as the control group, received no treatment. Wound healing was established by scoring of the rate of wound healing on Days 3, 6, 9, and 12. Histological observations were made on the same days as the scoring studies. The bioadhesive gel formulation that included CsA SLNs increased the rate of mucosal repair significantly.
Conclusion: This study has shown that the bioadhesive gel formulation containing CsA SLNs reported here is a promising candidate for the topical treatment of recurrent aphthous stomatitis.

Keywords: SLNs, buccal application, wound healing, oral mucosal disease