Desenvolvimento de forma farmacêutica semissólida contendo micropartículas com Clorexidina e Timol

Abstract

Introduction: chlorhexidine (CHX) and thymol are antimicrobials, both with activity against biofilms of various species of microorganisms, such as Staphylococcus aureus. The combination of these Active Pharmaceutical Ingredients (APIs) can generate a synergistic action. In polymeric microparticles, APIs can be incorporated, reducing the likelihood of unwanted effects and increasing the possibilities of use in pharmaceutical products. Objective: to develop a semisolid pharmaceutical formulation with a microparticulate product containing CHX and thymol. Methods: microparticles, prepared by freeze-drying, were optimized using a 32 factorial design (FD 32). A simultaneous dosing method for CHX and thymol was optimized and validated, with the aid of the Box-Behnken design (BBD) statistical tool, by High Performance Liquid Chromatography with diode array detector (HPLC-DAD). The microparticulate product was characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). In the accelerated stability study, periods of 30, 60 and 90 days were evaluated, with HPLC-DAD dosing and thermogravimetric analysis (TG). An antimicrobial

potency assay was developed, validated and performed using microparticles using the agar- cylinder diffusion technique. A semi-solid formulation was developed, using Poloxamer 407

(P407) as a base for incorporating microparticles containing CHX and thymol. The in vitro release kinetics of the final product were determined in an in vitro release test using an orbital shaker. Results: in PF32, no statistically significant differences were observed regarding the working ranges and parameters evaluated. In validating the analytical method by HPLC-DAD: it was considered linear for CHX (r=0.9998), concentration between 4.8 and 19.2 μg/mL, with homoscedastic residues; and for thymol (r=0.9996), concentration between 8.0 and 32.0 μg/mL, with heteroscedastic residues, requiring adjustment with Weighted Least Squares (WLS), with weight (wi) 1/x2. The lower limits of detection (LOD) and quantification (LOQ) were, respectively, 1.3961 and 4.6593 μg/mL for CHX, and 1.3487 and 4.0869 μg/mL for thymol. The selectivity was demonstrated under forced storage conditions, with the acidic environment being the one that most caused the appearance of degradation peaks. For precision and accuracy, the coefficients of variation were less than 5%. The results obtained in BBD, carried out to optimize the analytical method, were used to assess robustness. XRD and SEM analyzes showed microparticles with an amorphous character and a porous surface, respectively. In the forced stability test, no degradation products were observed. The antimicrobial potency test developed was considered linear, selective, precise, accurate and robust, meeting the validation parameters. In the potency test, the microparticulate product containing CHX and thymol, compared to a placebo standard contaminated with CHX, showed a potency of 1450.97 μg/mL. The in vitro release kinetics of the final product developed demonstrated a similar dissolution kinetic profile, with release greater than 85% in 60 minutes, for both APIs. Conclusion: The semi-solid final product with microparticles containing CHX and thymol presents itself as a promising option for antimicrobial therapies, especially in the field of dentistry.