Standardization of oral mucosa barrier models, experimental conditions and use of microneedles as permeation enhancer for in vitro permeation studies

Author(s)

Luciano Serpe

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2016-02-24

Examining board members

Michelle Franz Montan; Renata Fonseca Vianna Lopez; Renê Oliveira do Couto; Giovana Tofoli; Cíntia Maria Saia Cereda

• Advisor: Michelle Franz Montan; Francisco Carlos Groppo

Abstract

The use of topical formulations in the oral cavity presents low efficiency because of the complexity and variability of the mucosal lining and hard accessibility of deep tissues, as dental pulp. Microneedles have been reported as efficient and painless transdermal and transmucosal drug systems for local and/or systemic effect and could improve action of topical drugs in Dentistry. Aiming at improving the bioavailability of topical formulations, in vitro permeation studies are very important because it may allow predicting the behavior of these formulations in front of the barrier used. However, there is no barrier model that mimics the actual conditions of the oral cavity. In this context, this study aimed to standardize thick tissue barriers of the oral cavity from pigs, adapt diffusion cells and experimental conditions for performing in vitro permeation studies with these barriers, in order to develop topical products in Dentistry. Moreover, to evaluate the efficiency and applicability of microneedles coated or not as in vitro absorption enhancers in this methodology. Article 1: pig thick palate tissues (with and without bone) and experimental conditions were standardized to carry out in vitro permeation experiment. The microneedle device Dermaroller® (0.2, 0.5 and 1 mm length) was applied in those tissues, which were mounted in adapted Franz-type vertical diffusion cells. The Flux and the permeation enhancement factor (EF) of the local anesthetics lidocaine and prilocaine were evaluated. Tissues were successfully standardized and the adapted Franz cell allowed to maintain the experimental conditions through the 12h of permeation assay. The permeation of the analyzed drugs has occurred eventually, demonstrating the effectiveness of the barriers. The microneedles pretreatment on tissues increased the permeation flux of the tested drugs, in comparison to control groups. Article 2: microneedles of 0.7 mm were coated with the drug Sulforhodamine B, and applied on the porcine buccal mucosa surface, followed by permeation tests (24h). Two types of salivary flow (static and dynamic) were simulated inside the donor chamber and were compared with a moistened gauze as a negative control. We evaluated the onset time to permeation (Lag Time), flux and EF. Either of the simulated salivary flux affected the permeation profile of the model drug, by means of increasing drug permeation, as compared to the negative control, demonstrating the importance of saliva during in vitro permeation studies. General conclusions: tissues were standardized and allowed to perform permeation assays with adapted Franz cells. The use of microneedles in those barriers was effective to increase the permeation of drugs under the conditions evaluated. The presence of salivary flow has proved to be important to simulate the real conditions of the oral cavity in in vitro permeation, which might have an essential role on permeation dynamics across the tissue. This study represents an advancement to perform in vitro permeation assays, aiming at the improvement of topical formulations and absorption enhancers for use in Dentistry (AU)

• FAPESP's process: 12/02492-5 - In vitro study of the microneedles system appicability for topical anesthesia in swine oral tissues.
• Grantee: Luciano Serpe
• Support Opportunities: Scholarships in Brazil - Doctorate