VALIDATION OF A SIMPLE METHOD FOR SIMULTANEOUS DETERMINATION OF LIPOIC ACID AND RESVERATROL BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

A high-performance liquid chromatography-ultraviolet (HPLC-UV) method was developed and validated for simultaneous determination of Resveratrol (RSV) and Lipoic Acid (LA). A C18 column was used with a mobile phase consisting of acetonitrile and 0.01M phosphoric acid (60:40). The detection wavelength was at 235 nm. The method was specific in the presence of pharmaceutical excipients widely used in solid dosage forms or lipid-core nanocapsules. The results demonstrated linearity between 5 and 50 µg/mL for RSV and 30 and 120 µg/mL for LA. The method presented precision and accuracy (RSD <5%). In addition, the developed method was considered robust. Therefore, the developed method can be applied successfully for simultaneous determination of RSV and LA in the proposed conditions, with a potential application to assay both drugs in several dosage forms

Lipid core nanocapsules-loaded tacrolimus: Development and evaluation of quality parameters

This study aimed to revalidate an HPLC-based analytical methodology to determine&nbsp; tacrolimus within lipid-core nanocapsules and to evaluate the quality of such nanosystems. Chromatographic separation was achieved by employing a C18 column as a stationary phase and a ternary mixture of acetonitrile: water: phosphoric acid (700:299:1 v/v) as the mobile phase. The revalidated method proved to be linear in the range of 1-60 µg.mL−1 for tacrolimus (r2 &gt;0.999). Detection and quantification limits were 45.38 ng.mL-1 and 137.51 ng.mL-1, respectively, which assures the methodology sensitivity. The method was also precise (RSD = 1.78% between samples). Besides, the methodology demonstrated accuracy and robustness. The lipid-core nanocapsules-loaded tacrolimus showed exclusively nanosized particles (±190 nm and polydispersity index of ≤v0.2), negative zeta potential (-13.67±1.16), and slightly acidic pH (5.58 ± 0.06), with a content of 98.90±2.32%&nbsp; and encapsulation rate of 99.23±0.32%.&nbsp; Tacrolimus-loaded in lipid-core nanocapsules-loaded tacrolimus showed stability for at least 30 days at room temperature and a sustained release profile compared to the drug in solution

The use of antioxidants as fotoprotector enhancer : a scientific approach

A pele, por constituir uma interface com o meio ambiente e devido a sua função barreira, é considerada um órgão alvo para os efeitos nocivos da luz solar. A ação da radiação ultravioleta sobre a superfície cutânea leva à geração excessiva de radicais livres, os quais estão relacionados a diversas patologias da pele (queimaduras, fotoimunosupressão e fotocarcinogênese) e ao próprio processo de envelhecimento. Tendo em vista os casos crescentes de câncer de pele e outros efeitos adversos da exposição solar crônica, conclui-se que a terapia fotoprotetora atual é insuficiente. De forma a aperfeiçoar a fotoproteção, observa-se, nos últimos anos, um crescente interesse em substâncias com propriedades antioxidantes, capazes de seqüestrar radicais livres, reduzindo os danos oxidativos produzidos na pele e até mesmo com a habilidade de inibir sinais de transdução induzidos pela radiação ultravioleta, que conduzem a diversos processos patológicos e degenerativos. A proposta desta revisão é analisar, com base científica, não só os benefícios, mas também os aspectos negativos de vários antioxidantes de uso tópico passíveis de serem incorporados em formulações fotoprotetoras.The skin, consisting of an interface with the environment and due to its barrier function, is considered a target organ for the noxious effects of the solar light. The action of the ultraviolet radiation on the cutaneous surface leads to an excessive generation of free radicals that are related to several pathologies of the skin (sunburns, photoimunosupression and photocarcinogenesis) and to the aging process. Due to increasing numbers in cases of skin cancer and other adverse effects of the chronic solar exhibition, we may conclude that actual photoprotection therapy is insufficient. In order to improve the photoprotection, it is noticed, in recent years, an increasing interest in substances with antioxidant properties, capable to scavenge free radicals, thus reducing the oxidative damages produced in the skin and yet with the ability to inhibit transduction signs, induced by the ultraviolet radiation, that lead to several pathological and degenerative processes. The proposal of this revision is to analyze, with scientific base, not only the benefits, but also the negative aspects of several antioxidants of topical use susceptible to be incorporated in sunscreens formulations