Predicting skin absorption of caffeine from complex vehicles using experimental design
The purpose of the present study was to investigate the relationship between skin absorption enhancers such as urea, alcohol and glycol including 1, 2-pentanediol and skin diffusion of caffeine from aqueous solutions into a receptor compartment (µg/cm2) using a full factorial design 24.
The predicted values obtained were close to the experimental values indicating that the model is suitable. This finding is promising since it shows that result prediction and optimization can be achieved with a few experiments only.
The development of personal care or dermopharmaceutical products requires a detailed understanding of the relationship between formulation parameters, quality attributes and skin absorption achievements (1) .
Also, transdermal drug delivery offers an attractive alternative to conventional oral and injection therapies. Drugs have to penetrate the deeper skin layers or permeate the skin. Human skin, however, represents an effective, selective barrier to chemical permeation (2). Unfortunately, only a few drugs possess the physicochemical properties necessary for this route of delivery. Most drugs are unable to cross the skin in quantities required for successful systemic therapy. The drug penetration rate can, therefore, be increased by the use of penetration enhancers.
In particular, it is necessary to establish a science-based rationale and a design space to identify multidimensional combinations of the many causal factors that determine target quality.
It is however difficult (and time consuming) to obtain an optimized formulation with rapid and deep or massive skin penetration using a traditional formulation screeni ...