Percutaneous absorption of topically applied mannitol and progesterone was compared in vivo with the hairless and hairy rat. Urinary excretion and skin concentration profiles after topical application of mannitol demonstrated that hairless rat skin was a "leakier" barrier to percutaneous absorption of polar compounds than was hairy rat skin, independent of formulation. Liposomal, but not aqueou...

To use a diffusion model for predicting skin absorption requires accurate estimates of input parameters on model geometry, affinity and transport characteristics. This review summarizes methods to obtain input parameters for diffusion models of skin absorption focusing on partition and diffusion coefficients. These include experimental methods, extrapolation approaches, and correlations that re...

This presentation will outline the basic problems in getting an active ingredient (or drug) to enter the skin via topical absorption through the Epidermis. I will discuss the physical problems preventing this associated with the skin’s natural barrier system, the rate of absorption and how we can modify this process to enhance absorption for skin rejuvenation or reduce absorption in the case of...

The percutaneous absorption of hydrocortisone and testosterone was studied following their application to the vulvar and ventral forearm regions of pre- and post-menopausal women. Percutaneous absorption of hydrocortisone was significantly greater in vulvar skin than forearm skin in both pre- and post-menopausal women (P < 0.05, respectively), whereas the percutaneous absorption of testosterone...

The number of farmers who have suffered from non-fatal acute pesticide poisoning has been reported to vary from 5.7% to 86.7% in South Korea since 1975. Absorption through the skin is the main route of exposure to pesticides for farmers who operate with them. Several in vitro tests using the skins of humans or animal and in vivo tests using laboratory animals are introduced for the assessment o...

Objective: Lorazepam is a sedative that may be used for the management of anxiety, insomnia, and chemotherapy-induced nausea and vomiting. Lorazepam can be incorporated into transdermal bases such as Lipoderm, referred to as Phospholipid Base, for drug delivery across the skin. The purpose of this study is to characterize the percutaneous absorption of lorazepam 5 mg/g in Phospholipid Base, whe...

Fragrance materials are widely used in cosmetics and other consumer products. The Research Institute for Fragrance Materials (RIFM) evaluates the safety of these ingredients and skin absorption is an important parameter in refining systemic exposure. Currently, RIFM's safety assessment process assumes 100% skin absorption when experimental data are lacking. This 100% absorption default is not s...

Animal models are important tools to predict human in vivo percutaneous absorption/penetration. Monkey, pig, rat, rabbit, guinea pig, hairless rodents, such as hairless rat, hairless mouse, hairless guinea pig and hairless dog, are among the most used animals for this purpose. Each animal model has its own advantages and weakness or limitation. To better correlate animal data with human skin ab...

and underlayed viable epidermis and dermis. Because the SC is highly lipophilic, dry and a relatively effective percutaneous barrier, skin penetration is influenced by physicochemical properties of compounds. Hydrophobic compounds penetrate more easier than hydrophilics and lower than high molecular weight. Relationships between penetration flux and physicochemical properties include: lipophili...