Enhancing effect of essential oils on the penetration of 5-fluorouracil through rat skin.

Three essential oils as penetration enhancers for 5-fluorouracil (5-FU) were studied using excised rat skin. The oils used were eucalyptus, peppermint and turpentine. Azone was used for comparison. The enhancing effect of the oils was found to be less than that of azone, but all the oils used enhanced the permeation of 5-FU. Eucalyptus oil was found to be the most active, causing about 60 fold increase, while peppermint and turpentine caused 46 and 28 fold increase, respectively. Eucalyptus oil was further studied by grading it into 5 fractions according to difference in boiling points. It was found that their activities increased as their boiling point increased. With all enhancers increased partition coefficients were observed but the diffusion coefficient values obtained were comparatively higher. The mode of action of these accelerants may be described by combined processes of partition and diffusion, the diffusion process being dominant.