Galenic and Biopharmaceutical Study of the Triamcinolone Acetonide and Lidocaine Hydrochloride Semisolid Formulations for Buccal Administration

Abstract

The mouth can be affected by important inflammatory processes resulting from localized or systemic diseases, such as diabetes, AIDS, and leukemia, among others, which are manifested in various types of buccal sores, typically presenting pain [1]. The present work focuses on the design, formulation, and characterization of four semi-solid formulations for oral mucosa in order to symptomatically treat these painful processes. The formulations have two active pharmaceutical ingredients: triamcinolone acetonide (TA) and lidocaine hydrochloride (LIDO). The formulations also contain Orabase® as an excipient, which is a protective, hydrophobic, and anhydrous adhesive vehicle, used to retain or facilitate the application of active pharmaceutical ingredients (APIs) to the oral mucosa. After designing the formulations, the validation of the analytical method was performed to achieve reliable analytical results. Franz-type diffusion cells were used to perform drug release studies using synthetic membrane, and permeation studies using buccal mucosa, permitting the estimation of the amount and rate of TA permeated across this mucous membrane. Further, the amount of TA retained within the tissue was estimated, as this is where it performs its anti-inflammatory activity, and showed no significant differences between the 0.05% TA + LIDO and 0.1% TA + LIDO formulations (p > 0.05). Therefore, the results demonstrate the suitability of the administration of the lowest concentration of TA tested, which achieved a similar efficacy as higher concentrations and reduced the potential systemic effects of corticoid administration. Furthermore, sublingual permeation studies were carried out to evaluate a scenario of continuous contact of the tongue with the applied formulation. The four formulations studied show pseudoplastic and thixotropic behavior, ideal for topical application. These results provide evidence for the potential of these topical formulations for the treatment of inflammatory processes in the buccal mucosa. Keywords: triamcinolone acetonide; buccal administration; semisolid formulations; thixotropic behavior; lidocaine hydrochloride; Franz-type diffusion cells