Design of emulgel platforms for local propolis delivery: The influence of type and concentration of carbomer

Abstract

Emulgel systems gelled by adding carbomer 934P (C934P) have shown suitable physicochemical characteristics for propolis delivery aiming the therapy of dermatological disorders. However, there are other types of carbomers toxicologically preferable with different and important physicochemical properties to be utilized in emulgel systems, such as Carbopol 974P (C974P) and Carbopol 971P (C971P). In this sense, this work investigated formulations of different carbomer types (C934P, C97P and C974P) and concentrations, according to a factorial design 32. The systems were evaluated as mechanical textural and rheological characteristics. The physical stability of formulations also enabled the selection of the best formulations, which were evaluated as in vitro drug delivery. The texture profile analysis showed that C934P and C974P, at 1% (w/w) concentration, were responsible for improved mechanical characteristics. These same formulations were the only ones that displayed stability against centrifugation and were selected to the other tests. When submitted to rheological analysis they showed non-Newtonian pseudoplastic behavior and were viscoelastic. Rheological and textural mechanical characteristics confirmed the influence of temperature, type, and concentration of carbomer in the systems. The incorporation of propolis increased the softness of systems, suggesting easy local administration. Thus, emulgels composed of C934P or C974P 1% (w/w) are promising systems for controlled release of propolis and are worthy of further studies.