In vivo evaporation rate of benzyl alcohol from human skin.
J Pharm Sci 2004 Feb; 93(2):515-520
The evaporation rate of benzyl alcohol from the human volar forearm under controlled conditions in vivo shows a similar dependence on airflow and time to that seen in earlier in vitro studies. After an initial time lag associated with the apparatus, evaporation rate over a 2-h time period post-dose was satisfactorily described by a single exponential decay with a rate constant proportional to airflow over the skin, nu. The cumulative percentage of dose evaporated after 2 h ranged from 16% at nu = 20 mL min(-1) to 52% at nu = 100 mL min(-1). The absorption rate constant determined by an analysis of the in vivo data was equivalent to that determined in vitro, whereas the evaporation rate constants were related by the inverse ratio of the headspace volumes. The latter finding suggests that a simple laminar flow model can satisfactorily describe evaporation in both systems over the range of airflows used.
Skin; In-vitro-studies; Skin-absorption; Models; Alcohols; Humans; In-vivo-study; In-vitro-study
Gerald B. Kasting, College of Pharmacy, The University of Cincinnati Medical Center, P.O. Box 670004, Cincinnati, Ohio 45267-0004, USA
Research Tools and Approaches: Exposure Assessment Methods
Journal of Pharmaceutical Sciences
University of Cincinnati