Improving the sensitivity of in vitro skin penetration experiments.
The institution of a readily-implemented sample screening and data handling procedure for in vitro skin penetration studies yields substantial improvements in sensitivity for distinguishing between formulations, treatments, penetrants, etc. The procedure involves four steps: 1) prescreen the tissue samples to determine their intrinsic permeability; 2) apply treatments using a randomized complete block (RCB) design, with blocking by tissue permeability; 3) apply a variance-stabilizing transformation to the penetration data, followed by outlier testing; and 4) analyze the transformed data according to an RCB analysis of variance, using tissue permeability as the blocking variable. For penetration studies in which high sample variability is a concern, the above procedure commonly yields a sensitivity advantage of several-fold versus alternative methods of comparison.
Kasting
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Procter & Gamble Company, Miami Valley Laboratories, Cincinnati, Ohio 45253-8707.
Filloon
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Francis
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Meredith
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MP
D006801:Humans; D010539:Permeability; D012867:Skin / Q000378:metabolism*