ALECRIM-DO-CAMPO MICROEMULSION MOUTHRINSE: DEVELOPMENT, CHARACTERIZATION AND IN VITRO EVALUATION

TF02

Leite, MF (1); Leitão, DPS (1);  Sousa, IP (1); Campos, LMP (1); Polizello, ACM (1); Sousa, JPB (1); Bastos, JK (1); Lopez, RFV (1); Spadaro, ACC (1)

¹Faculdade de Ciências Farmacêuticas de Ribeirão Preto, USP.

Introduction: The use of antimicrobial mouthrinses to help the plaques supragengival control and gingivitis has been shown to significantly contribute to patients’ daily oral hygiene. Formulations based on microemulsions have several interesting characteristics such as the ability to protect labile drugs, their release control, and to increase their solubility and bioavailability. It has been demonstrated that extracts from Baccharis dracunculifolia (Bd), a Brazilian shrub species, popularly known as “alecrim-do-campo”, show anticariogenic properties, which suggests its appliance into oral care products. However, Bd extracts are poorly water soluble. Objective: In this work, we have developed a microemulsion in which Bd extract may be incorporated to produce a clear solution in an alcohol-free mouthrinse. Methodology: Four Bd extract - containing microemulsion systems (1) ethil oleate/Labrasol®/Plurol® (LP), (2) isopropyl miristate/PEG 40/Sorbytol (PSM), (3) ethil oleate/PEG 40/Sorbytol (PSO) and (4) ethil oleate/Baccharis dracunculifolia essencial oil/PEG 40/Sorbytol/Glycerol (PSG), were prepared in aqueous mixtures at room temperature, using the conventional titration technique. The pseudo-ternary phase diagrams were prepared at room temperature. The systems were characterized by optical microscopy, stability, rheology, pH, Light Scattering and electrical conductivity. The inhibitory effect on bacterial acid production was evaluated through the potentiometric measurement of pH from bacterial suspensions treated with serial concentrations of  Bd mouthrinse (0.016 a 0.32 µg/mL). For the antibacterial activity assay, the inhibitory effect on bacterial growth and the minimum inhibitory concentrations (MIC) were determined. Results: Two regions were identified in the first diagram (bifasic system and microemulsion) while three regions were identified on the others (bifasic system, emulsion and microemulsion). All systems displayed an oil-in-water microemulsion region. The system chosen for the mouthrinse presented  viscosity (12.40 cP), droplet size (19.53nm), conductivity (145.70 μS/cm), final pH (5.89), and relative density (1.0425g/mL). The inhibitory effect values obtained for the bacterial acid production were 12.56 – 53.38%. The IC₅₀ value was 0.25mg/mL. The MIC value was 560µg/mL. Conclusion: The Results indicate that these systems could be an interesting Bd vehicle for a mouthrinse and suggest that the final rising formulation has antimicrobial properties superior to the rough hydroetanolic extract, with low cytotoxic effect, turning it credible to clinical evaluation.