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PERCUTANEOUS ABSORPTION OF CATECHOL IN RAT AND HUMAN SKIN
| Title: | PERCUTANEOUS ABSORPTION OF CATECHOL IN RAT AND HUMAN SKIN |
| Author: | Jung, Connie Tom |
| Description: | Catechol may be used as a coupler in oxidative permanent hair dyes. A safety report by the Cosmetic Ingredient Review Expert Panel concluded initially that catechol used at a concentration of 1% or less in rinse-off products, did not pose any safety concerns. When catechol exposure was later reassessed, there was insufficient evidence to support the safety of hair dye products left on the scalp for a short period of time. When used in permanent hair dyes, it is not known how much catechol reaches the skin. The cosmetic industry has assumed that insignificant amounts remain on the skin after normal consumer use. This research addressed the deficiency of skin absorption data if catechol was used in a permanent hair dye. In vitro percutaneous absorption studies using flow-through diffusion cells were conducted by applying catechol in a hair dye product for 30 minutes to viable skin from the fuzzy rat or human skin from abdominoplasty surgery. In vitro and in vivo absorption studies were done by applying catechol in ethanol to fuzzy rat skin for 24 hours. Extended studies demonstrated the absorption of catechol initially retained in the skin. In vitro absorption (receptor fluid) and in vivo systemic absorption were compared. Dermal bioavailability was determined by noncompartmental pharmacokinetic analysis using plasma data obtained after topical application in vivo. These studies confirmed that catechol readily penetrated rat skin in vitro and in vivo. Although not completely oxidized in a hair dye, the percutaneous absorption of catechol from a permanent hair dye was minimal in rat and human skin, 4% and 2% of the applied dose, respectively. The developer played a critical role in reducing the amount of catechol available for absorption. From an ethanol vehicle, total percutaneous absorption of catechol was 89% of the applied dose in vitro and 61% in vivo. Catechol did not stay bound in the skin. Based on plasma data, dermal bioavailability was calculated to be 29%; this was a conservative estimate compared to the actual percent systemically absorbed of 52%. In vitro percutaneous absorption provided reasonable estimates of in vivo absorption. |
| Permanent Link: |
http://rave.ohiolink.edu/etdc/view?acc_num=ucin971368708
http://hdl.handle.net/2374.OX/12526 |
| Date: | 2000 |
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