Effects of isopropanol–isopropyl myristate binary enhancers on in vitro transport of estradiol in human epidermis: A mechanistic evaluation
✍ Scribed by Puchun Liu; Melinda Cettina; Judy Wong
- Book ID
- 102394577
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 137 KB
- Volume
- 98
- Category
- Article
- ISSN
- 0022-3549
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✦ Synopsis
The purpose of this study was to mechanistically investigate effects of isopropanol (IPA)-isopropyl myristate (IPM) binary enhancers on transport of a model drug, estradiol (E2) in human epidermis (stratum corneum þ viable epidermis) in vitro.
The study was focused on use of the same IPA-IPM compositions on both sides of the skin (''symmetric'' configuration) with saturated E2 (maximum thermodynamic activity). For E2 transport in all IPA-IPM compositions tested, stratum corneum still was the rate-limiting layer of human epidermis. The relative contributions to E2 flux enhancement were separated into the changes in solubility and diffusivity of E2 in stratum corneum. As a major factor, E2 solubility in stratum corneum was enhanced by 35 times with increasing IPA from neat IPM to neat IPA. E2 diffusivity in stratum corneum also played a significant role, which increased by 8 times from neat IPM to 50% IPA. Stratum corneum swelled more in IPM-rich region, decreased with increasing IPA, and even deswelled in neat IPA. IPA uptake correlated well to E2 solubility in stratum corneum; both linearly increased with increasing IPA. IPM uptake appeared to correlate to E2 diffusivity in stratum corneum; both maximized around 50% IPA.