Development of a highly persistent silicone-based sprayable emulsion containing essential oils for treatment of skin infections

Essential oils have known a renewed interest, particularly for their antimicrobial properties. In the field of skin delivery of essential oils, fluid oil-in-water (O/W) emulsions have been studied for several years in order to improve their stability. When dealing with infections of the upper skin layers, these vehicles, in spite of their low viscosity, must have a good skin persistence and also concentrate the essential oil components in the target skin layers. Given the well-known ability of alkylsiloxysilicate resins to induce a very substantive and non-occlusive film after cutaneous application in an appropriate preparation, it has been undertaken to use them to prepare a highly persistent O/W fluid emulsion of essential oil. Hence, after the successful development of a fluid silicone-in-water (Si/W) emulsion integrating a 100% trimethylsiloxysilicate resin, the essential oil was incorporated in this emulsion. The physical and chemical stabilities of the prepared emulsion were then studied in the final packaging under different storage conditions. In addition, the skin penetration profile of essential oil from this vehicle was investigated, ex vivo, on pig ear skin, using Franz diffusion cells and analytical techniques such as confocal Raman microscopy. As the developed vehicle was found to meet our delivery expectations, its skin tolerance has been proven by an in vivo chromametric evaluation of its irritant potential. The skin persistence of this emulsion containing an antimicrobial essential oil was then studied. Considering its properties, the developed emulsion is expected to represent a real asset in the treatment of skin infections, particularly infections of upper layers of human skin such as dermatophytosis

Chromametric assessment of drug skin tolerance: A comparative study between Africans and Caucasians skins

BACKGROUND/AIMS: During dermatological forms development, one of the simplest non-invasive techniques used to evaluate cutaneous tolerance of formulations is to monitor the color changes using a tristimulus chromameter. Most published tolerance studies involving chromametric measurements are performed on Caucasian subjects. However, in the context of drug formulation for African-type populations, it is not always relevant to transpose tolerance results obtained on Caucasians populations to African-type ones due to histological ethnic differences of the skin. The goal of this work was to assess whether tristimulus chromameter can be used to highlight color variations following the application of dermatological topics on black skin in order to validate skin tolerance studies made on African-type subjects. MATERIALS AND METHODS: After application of two commercial creams with opposite side effects (skin irritation and skin blanching) in both Africans and Caucasians populations, color variations were evaluated using a tristimulus chromameter in L* a* b* color system and compared between both populations. L* indicating color brightness, a* represents green and red directions and b* represents blue and yellow directions. RESULTS: While skin irritation resulted in a significant increase of a* parameter in both studied populations, the skin blanching resulted in a decrease of a* associated with an increase of L* . CONCLUSION: We established that tristimulus chromameter can be used to achieve in vivo skin tolerance study of dermatologic formulations in Africans despite their dark skin even though it appeared less sensitive. This study can speed up the development of dermatological forms dedicated to Africans and/or Caucasians subjects

Chromametric assessment of drug skin tolerance: A comparative study between Africans and Caucasians skins.

BACKGROUND/AIMS: During dermatological forms development, one of the simplest non-invasive techniques used to evaluate cutaneous tolerance of formulations is to monitor the color changes using a tristimulus chromameter. Most published tolerance studies involving chromametric measurements are performed on Caucasian subjects. However, in the context of drug formulation for African-type populations, it is not always relevant to transpose tolerance results obtained on Caucasians populations to African-type ones due to histological ethnic differences of the skin. The goal of this work was to assess whether tristimulus chromameter can be used to highlight color variations following the application of dermatological topics on black skin in order to validate skin tolerance studies made on African-type subjects. MATERIALS AND METHODS: After application of two commercial creams with opposite side effects (skin irritation and skin blanching) in both Africans and Caucasians populations, color variations were evaluated using a tristimulus chromameter in L* a* b* color system and compared between both populations. L* indicating color brightness, a* represents green and red directions and b* represents blue and yellow directions. RESULTS: While skin irritation resulted in a significant increase of a* parameter in both studied populations, the skin blanching resulted in a decrease of a* associated with an increase of L* . CONCLUSION: We established that tristimulus chromameter can be used to achieve in vivo skin tolerance study of dermatologic formulations in Africans despite their dark skin even though it appeared less sensitive. This study can speed up the development of dermatological forms dedicated to Africans and/or Caucasians subjects

Cymbopogon giganteus Chiov. essential oil: Direct effects or activity in combination with antibiotics against multi-drug resistant bacteria

The discovery of new antimicrobial agents is necessary due to the emergence of multi-drug bacterial resistance. The aim of this work was to study the direct and indirect antimicrobial activity of a Beninese sample of Cymbopogon giganteus essential oil (EOCG) on multi-drug resistant clinical bacteria, its chemical composition, and its cytotoxicity. Direct antimicrobial activity was tested by determination of minimal inhibitory concentration (MIC), and indirect activity, by determining Fractional Inhibitory Concentration Index using checkerboard [fractional inhibitory concentration indices (FICI); synergy: FICI ≤ 0.5; additivity: 0.5 < FICI ≤ 1]. EOCG composition was determined by GC -MS and GC-FID and cytotoxicity was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphényltetrazolium bromide (MTT) assay. p-Menthane derivatives (54.87%) and limonene (12.07%) were detected as major compounds by GC analysis. Our results confirmed the direct antimicrobial activity of EOCG, but here on clinical resistant strains (MIC from 0.125% v/v to 0.5% v/v). We also show synergistic effects between EOCG and amoxicillin with FICI ranges of 0.12– 0.5 against two Escherichia coli resistant clinical strains, synergistic to additive effects between EOCG and colistin or oxacillin/ampicillin, respectively, against Pseudomonas aeruginosa PA544 and Staphylococcus epidermidis SECN361 (two resistant clinical isolates). Our results also indicate that EOCG had low cytotoxicity (IC50: 67.06 ± 2.694 μg/ml)