Percutaneous Absorption Of Caffeine Research Articles

In-Vivo Tape Stripping Study with Caffeine for Comparisons on Body Sites, Age and Washing.

Assessing the percutaneous absorption of cosmetic ingredients using in-vitro human skin reveals certain limitations, such as restricted anatomical sites and repeated exposure, and to overcome these issues, in-vivo studies are required. The aim of the study is to develop a robust non-invasive in-vivo protocol that should be applicable to a wide range of application. A robust tape stripping protocol was therefore designed according to recent recommendations, and the impact of two different washing procedures on caffeine distribution in tape strips was investigated to optimise the protocol. The optimised protocol was then used to study the effect of age and anatomical area on the percutaneous absorption of caffeine, including facial areas which are not readily available for in-vitro studies. With tape stripping, a difference between the percutaneous absorption on the face (forehead, cheek) and the volar forearm was observed. No obvious difference was observed between percutaneous absorption in young and post-menopausal women, but this could be due to the limited number of subjects. This tape stripping protocol is now to be deployed to address many other factors, such as percutaneous absorption in other anatomical areas (e.g. abdomen, axilla, etc.), impact of repeated applications and effect of formulation.

PENETRATION TEST OF CAFFEINE IN ETHOSOME AND DESMOSOME GEL USING AN IN VITRO METHOD

Objectives: Caffeine has many functions including its use in the field of cosmetics. Nonetheless, the percutaneous absorption of caffeine is very low(9%), and the penetration of a substance such as caffeine in the skin is not desirable. Ethosomes and desmosomes are lipid vesicles created by themodification of liposomes containing phospholipids and ethanol or dimethyl sulfoxide (DMSO) as the penetration enhancer. The purpose of this studywas to compare the effectiveness of ethosomes and desmosomes as vesicles in increasing the penetration of caffeine.Methods: Ethosomes and desmosomes were prepared using phosphatidylcholine, ethanol/DMSO, and caffeine. Phosphatidylcholine was used in theform of phospholipon 90 g that was obtained from soybeans. Observations were done including the characteristic of ethosomes and desmosomes,organoleptic observation, homogeneity observation, and in vitro penetration test using Franz diffusion cell method.Results: The cumulative penetration of caffeine ethosome gel is 3316.46±218.51 μg/cm2, with flux 249.45±30.06 μg·cm−2·hr−1, and 62.35±4.52%. Thecumulative penetration of the desmosome gel is 2954.95±222.87 μg/cm2 with flux 381.68±34.91 μg·cm−2·hr−1 and 53.4±3.65%.Conclusions: It can be concluded that ethosome is more effective than desmosome in increasing the penetration of caffeine.

Effect of terpinyl acetate on the percutaneous absorption of caffeine in rats

Effect of terpinyl acetate on the percutaneous absorption of caffeine in rats

The role of hair follicles in the percutaneous absorption of caffeine

* In recent years, it has been suggested that hair follicles represent important shunt routes into the skin for drugs and chemicals [1-3]. * In vitro studies have shown the importance of skin appendages for skin penetration by hydrophilic compounds [4]. Investigation of follicular penetration in vivo has been difficult due to the absence of appropriate analytical methods or suitable animal model systems. * Recently, a new method was described that quantifies follicular penetration in vivo by using selective closure of hair follicles [5]. * Caffeine is frequently used in skin penetration experiments as a model for highly water-soluble compounds. Occlusion [6] and skin thickness [7] seem to have little influence on the penetration of caffeine. However, percutaneous absorption rates for caffeine exhibit regional skin differences in humans in vivo[1]. * The results of the present study demonstrate that a fast drug delivery of caffeine occurs through shunt routes. Therefore, hair follicles are considerable weak spots in our protective sheath against penetration into the body by hydrophilic substances. * We showed that there is a quantitative distinction between follicular penetration and interfollicular diffusion of caffeine in vivo. * These findings are of importance for the development and optimization of topically applied drugs and cosmetics. In addition, such properties must be considered in the development of skin protection measures. The skin and its appendages are our protective shield against the environment and are necessary for the maintenance of homeostasis. Hypotheses concerning the penetration of substances into the skin have assumed diffusion through the lipid domains of the stratum corneum. It is believed that while hair follicles represent a weakness in the shield, they play a subordinate role in the percutaneous penetration processes. Previous investigation of follicular penetration has mostly addressed methodical and technical problems. Our study utilized a selective closure technique of hair follicle orifices in vivo, for the comparison of interfollicular and follicular absorption rates of caffeine in humans. Every single hair follicle within a delimited area of skin was blocked with a microdrop of a special varnish-wax-mixture in vivo. Caffeine in solution was topically applied and transcutaneous absorption into the blood was measured by a new surface ionization mass spectrometry (SI/MS) technique, which enabled a clear distinction to be made between interfollicular and follicular penetration of a topically applied substance. Caffeine (3.75 ng ml(-1)) was detected in blood samples, 5 min after topical application, when the follicles remained open. When the follicles were blocked, caffeine was detectable after 20 min (2.45 ng ml(-1)). Highest values (11.75 ng caffeine ml(-1)) were found 1 h after application when the follicles were open. Our findings demonstrate that hair follicles are considerable weak spots in our protective sheath against certain hydrophilic drugs and may allow a fast delivery of topically applied substances.

Surface Recovery and Stripping Methods to Quantify Percutaneous Absorption of Caffeine in Humans

The percutaneous absorption of caffeine from two vehicles, an emulsion and an acetone solution, was quantified by in vivo techniques in humans. A surface recovery technique over a 6-h application and a stripping method after a 30-min application were performed on the volar aspect of the forearm on 12 volunteers. Caffeine was assessed by HPLC. Two phases were distinguished in the percutaneous absorption of caffeine: a higher filling up of the stratum corneum with the oil-in-water emulsion than with the acetone solution, which was then followed by a steady-state flux corresponding to the penetration in the living tissues. The permeability constants (Kp) with emulsion and acetone were 1.59⋅10−4 and 9.53⋅10−8 cm/h, respectively. The stripping method showed concentrations of caffeine in stratum corneum that were five times higher with emulsion (212 ng/cm2) than with acetone (37 ng/cm2). With acetone as a vehicle, ~40% of caffeine of the cornified layer was found around the treated area. This sizeable lateral spread within the stratum corneum was not observed with the emulsion.

Cutaneous Blood Flow and Percutaneous Absorption: A Quantitative Analysis Using a Laser Doppler Velocimeter and a Blood Flow Meter

Cutaneous blood flow has been directly quantitated in vivo for the first time without animal death utilizing the rat skin sandwich flap. This was accomplished by conducting experiments that made a direct correlation between two instruments: a laser Doppler velocimeter and an electromagnetic blood flow meter. Data demonstrate that the correlation between these two instruments is high and reproducible (r = 0.96) with a small (1.3%) coefficient of variation. Blood flow to skin in the unmanipulated state varies from 0.7 to 1.2 mls/min in an anesthetized rat. Application of the blood flow correlation to the determination of percutaneous absorption of caffeine across human skin and benzoic acid across rat skin demonstrates that assuming cutaneous blood flow is a particular value day to day in any skin type results in an apparent wide range of total compound absorbed across that skin on independent occasions. Utilizing actual blood flow measurements to calculate the amount of chemical absorbed reduces the range of variability in the total amount of chemical absorbed and provides a more accurate knowledge of events occurring during a particular time of the absorption process. Quantitation of cutaneous blood flow will be useful in physiologic and pharmacologic studies where actual cutaneous blood flow is likely to be important to the processes studied, e.g., delivery of drug to skin, metabolism within the skin, and disposition of drug to blood and skin following topical drug application.