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

The mouth can be affected by important inflammatory processes resulting from localized or systemic diseases such as diabetes, AIDS and leukemia among others, and 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 formula also contains Orabase^® as an excipient which is a protective, hydrophobic, and anhydrous adhesive vehicle, used to retain or facilitate the application of active pharmaceutical ingredients (API) 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. As well, the amount of TA retained within the tissue was estimated, where it performs its anti-inflammatory activity, and showing no significant differences between the 0.05% TA + LIDO and 0.1% TA + LIDO formulations (p > 0.05). Therefore, results evidence the suitability of the administration of the lowest concentration of TA tested, achieving similar efficacy, and decreasing the potential systemic effects of corticoid administration. Besides, sublingual permeation studies were carried out to evaluate a scenario of a continuous contact of the tongue with the applied formulation. The four formulations studied show a pseudoplastic and thixotropic behaviour, ideal for topical application. These results evidence the potential of these topical formulations for the treatment of inflammatory processes in the buccal mucosa.