CLINICAL PHARMACOLOGY:
The exact mechanism of action of tretinoin is unknown although retinoids are believed to exert an effect on the growth and differentiation of various epithelial cells. When applied topically, however, there was no noted increase in desmosine, hydroxyproline, or elastin mRNA in human skin. In addition, the role of the irritative nature of this product in effecting the positive effects attributed to this product for its indication has not yet been fully determined.
The transdermal absorption of tretinoin from various topical formulations ranged from 1% to 31% of applied dose, depending on whether it was applied to healthy skin or dermatitic skin. When percutaneous absorption of RENOVA was assessed in healthy male subjects (n=14) after a single application, as well as after repeated daily applications for 28 days, the absorption of tretinoin was less than 2% and endogenous concentrations of tretinoin and its major metabolites were unaltered.
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