In vitro skin penetration of petrolatum and soybean oil and effects of glyceryl monooleate.

OBJECTIVES: Petrolatum and soybean oil are common ingredients incorporated in topical skin formulations for skin protection and moisturization. However, the stratum corneum (SC) penetration kinetics of these two cosmetic ingredients has not been systematically studied. Glyceryl monooleate (GlyMOle) has been shown to enhance skin penetration of various compounds. It was hypothesized that GlyMOle could enhance skin penetration of petrolatum and soybean oil. This study aimed to examine the in vitro skin penetration of petrolatum and soybean oil in the presence or absence of GlyMOle. METHODS: Skin permeation experiments were conducted using the in vitro Franz diffusion cell model with split-thickness human skin and human epidermal membrane (HEM). The effect of permeant dose and the kinetics of permeant penetration were examined with and without GlyMOle in vitro. RESULTS: Petrolatum and soybean oil were found to permeate across HEM, and no effect of GlyMOle on skin permeation into the receptor chamber was observed. GlyMOle enhanced the penetration of petrolatum into the split-thickness skin at 50 µg dose (petrolatum:GlyMOle, 49 : 1, w/w). However, no effect of GlyMOle on petrolatum penetration was observed at 200 µg dose (of the same petrolatum:GlyMOle ratio), indicating a dose-dependent effect. GlyMOle at the level used in the study did not enhance the penetration of soybean oil with 50 and 200 µg doses at any timepoints. CONCLUSION: GlyMOle was a skin penetration enhancer for petrolatum under the in vitro conditions identified in this study.

Fluorescent silica colloids for study and visualization of skin care products.

BACKGROUND: The efficacy of skin care products depends on the time and dynamics of their absorbance by the skin, and its spatial distribution on the skin. Regular scrape-based methods may depend on the operator and are destructive and invasive in nature. Here, we describe a novel method based on non-contact optical measurements to trace the location and dynamics of skin care products on the skin. METHODS: We use fluorescent silica colloidal particles of micron sizes at a rather small concentration as non-invasive tracers. As an example of skin care products, we use two base materials: either glycerin or vaseline. A mixture of each product with fluorescent particles is applied on human skin. The amount of fluorescence is monitored by means of a fluorescent spectrometer. The scraping method is used to compare with the spectroscopic measurements. RESULTS: Fluorescent tracers make the skin care product visible under UV light. This allows obtaining an optical image of the spatial distribution of the product on the skin. The quantitative data of fluorescence are well correlated with the scrape data. Comparison of the difference in the spectral and scraped mass data reveals the details of accumulation of the skin products in skin cracks and crevices. CONCLUSION: We described an efficient non-invasive benign method to quantify dynamics and to perform mapping of emollients and humectants on the skin.

Emulsiones líquida-cristalinas estabilizadas con estearato de trietanolamina y ácido esteárico: influencia del método de preparación en las propiedades y en la formación de gotas secundarias / Stabilized liquid-crystalline emulsions with triethanolamine stearate and stearic acid: preparation method influence in the properties and formation of secondary droplets

Se desarrolló una metodología que permite obtener emulsiones de vaselina líquida estabilizadas con estearato de trietanolamina y ácido esteárico con características líquida-cristalinas en las que las gotas se agrupan formando gotas secundarias de unos 15 mcrom de diámetro. La formación de estas gotas secundarias, que es una consecuencia de la presencia de cristales líquidos lioptrópicos en las emulsiones, trae como consecuencia una disminución de la viscosidad. El reemplazo de parte de la vaselina líquida de estas emulsiones por otros emolientes de mayor capacidad de penetración dérmica, tales como el miristato de isopropilo y el 2-octil-1-dodecanol, no disminuye las características líquida-cristalinas, lo que permite obtener otras emulsiones más adecuadas para usos farmacéutico y cosmético

It has been developed a methodology which allows obtaining mineral oil emulsions stabilized with triethanolamine stearate and stearic acid with liquid-crystalline characteristics where droplets cluster themselves forming secondary droplets of 15 microm diameter. The formation of the mentioned secondary droplets, which are a consequence of the presence of lyotropic liquid crystals in the emulsions, produces a diminution of the viscosity. The replacement of part of the mineral oil of these emulsions for others emollients with greater dermal penetration capacity, such as isopropyl myristate and 2-octyl-1-dodecanol, does not diminish the liquid-crystalline characteristics, granting the obtainment of more adequate emulsions for pharmaceutical and cosmetic usage

In vivo measurement of human skin absorption of topically applied substances by a photoacoustic technique.

A photoacoustic technique is used for studying topically applied substance absorption in human skin. The proposed method utilizes a double-chamber PA cell. The absorption determination was obtained through the measurement of the thermal effusivity of the binary system substance-skin. The theoretical model assumes that the effective thermal effusivity of the binary system corresponds to that of a two-phase system. Experimental applications of the method employed different substances of topical application in different parts of the body of a volunteer. The method is demonstrated to be an easily used non-invasive technique for dermatology research. The relative concentrations as a function of time of substances such as ketoconazol and sunscreen were determined by fitting a sigmoidal function to the data, while an exponential function corresponds to the best fit for the set of data for nitrofurazona, vaseline and vaporub. The time constants associated with the rates of absorption, were found to vary in the range between 10 and 58 min, depending on the substance and the part of the body.

Drug penetration as studied by noninvasive methods: fourier transform infrared-attenuated total reflection, fourier transform infrared, and ultraviolet photoacoustic spectroscopy.

The penetration of the drugs dithranol and methoxsalen from semisolid Vaseline formulation into an artificial dodecanol-collodion membrane was followed by three spectroscopic methods; they are, step-scan Fourier transform infrared (FTIR) photoacoustic spectroscopy (PAS) with phase modulation, FTIR-attenuated total reflection (FTIR-ATR), and ultraviolet (UV) PAS. The uptake of the drug in the membrane was quantified by monitoring the dependence of an appropriate drug band on the penetration time. The PAS experiments were carried out with various modulation frequencies for generating various sampling depths. Based on Fick's second law, the diffusion coefficient was derived by numerical fitting of the experimental data. It appears that the diffusion coefficient for the drug in the membrane depends on the distance. The comparative studies demonstrate that FTIR-ATR is favored for permeation studies, whereas the PAS techniques are capable of providing the drug penetration profile in the membrane. Thus, extended experimental data are available for new insight into the penetration process. However, because of the photacoustic cells at hand, PAS is only suitable for in vitro studies.

[Studies on the pharmaceutical availability of chlortetracycline hydrochloride in selected ointment bases]. / Badania dostepnosci farmaceutycznej chlorowodorku chlorotetracykliny w wybranych podlozach masciowych.

Influence of non-ionic tensides on liberation of chlorotetracycline hydrochloride from ointment bases was investigated. Non-ionic tensides were found to enhance liberation of chlorotetracycline hydrochloride from lipophilic ointment bases, while liberation of this antibiotic from hydrophilic ointment bases proved to be depressed.