Produção de formulação de cristal líquido contendo óleo de Croton tiglium L. para aplicação em peeling químico

Abstract

With technological advances and concerns about the characteristics of the skin, society has been looking for new procedures that lead to skin rejuvenation. Historically, the use of the chemical peeling formulation described by Baker and Gordon and improved by Hetter, contains phenol, Croton tiglium oil extracted from this plant’s seeds, Septisol® and water in its composition. This formulation is effective and offers better results when compared to others peelings used in the dermatological clinic with the same purpose. However, it can cause serious side effects due to the presence of phenol in the composition, in addition to having an extemporaneous characteristic because of its low physical stability. Thus, the aim of this study was to develop liquid crystals (LC) containing croton oil, as a carrier system and controlled release of the active compound in the chemical peeling formulation. The 26 proposed formulations were obtained through a pseudoternary phase diagram, containing croton oil (OC) as active/oil phase, ultrapure water as solvent/aqueous phase and Brij 58® (polyoxyethylene 20 cetyl ether) as the surfactant, maintaining the base components proposed in the original formulation, except phenol. After the preparation of the 26 formulations (varying the components: OC 10-80%, Brij 58® 10-40%, ultrapure water 10-80%), an evaluation of the liquid-crystalline phase formation was carried out by polarized light microscopy and macroscopic characterization, and the formulations that presented a lamellar liquid-crystalline phase were selected (4 formulations). Subsequently, the macroscopic and rheological characteristics, pH, particle size, polydispersion index and zeta potential were analyzed. Among the evaluations, formulation 8 was highlighted, with promising results when compared to the others (pH 6.71, zeta potential -23.85mV, particle size 427.25 nm). However, a modification in the formulations was proposed because of changes in stability, adding a thickening agent (hydroxyethylcellulose - HEC) in the aqueous phase and change in mixing time (an increase of 3 minutes), repeating the analytical tests. After insertion of HEC in the formulation, there was an improvement in the results obtaining an average pH=5.18, zeta potential= -41.53 mV, particle size= 503.58 nm, also being visualized improvement in the macroscopic characteristics, and maintenance of the behavior rheological after 28 days. Furthermore, high encapsulation efficiency (EE%) of the OC was quantified (1,218.13 ± 77.56), and cytotoxicity of the formulation increased by the presence of the surfactant Brij58 was observed. In general, evaluating the results obtained, the formulation with HEC had a more stable and expected behavior in the aspects evaluated for a topical application formulation.