ABSTRACT
This chapter presents general principles of the in vivo assessment of dermal penetration methodology, and highlights the problems that may exist. Animal models are used extensively in dermal absorption studies to evaluate dermal toxicity of topically applied compounds since many of these studies cannot be performed using human subjects. In vivo dermal penetration studies have utilized small laboratory rodents, such as mice, rats, guinea pigs, and rabbits. The meaningful use of nonradioactive test compounds in in vivo dermal penetration studies depends on the sensitivity of analytical techniques to measure the concentration in blood and urine. In vivo, loss of chemicals from the skin surface can occur by evaporation, abrasion, or exfoliation of the stratum corneum. Air flow, temperature, and humidity can be factors affecting surface loss. An alternative approach to achieve agreement between in vitro and in vivo penetration measurements for lipophilic compounds has been the use of receptor fluids containing surfactants.
