Permeation study of five formulations of alpha-tocopherol acetate through human cadaver skin
Alpha-tocopherol (AT) is the vitamin E homologue with the highest in vivo biological activity. Alpha-tocopherol protects against the carcinogenic and mutagenic activity of ionizing radiation and chemical agents, and possibly against a UV-induced cutaneous damage. For stability consideration, AT is usually used as its prodrug ester, alpha-tocopherol acetate (ATA), which once absorbed into the skin is hydrolyzed to AT, the active form. The objective of this research was to characterize in vitro the permeation properties of ATA from various solutions and gel formulations. Permeation studies were conducted using modified Franz diffusion cells and human cadaver skin as the membrane. Specifically, 5% (w/w) ATA was formulated in the following vehicles: ethanol, isopropyl myristate, light mineral oil, 1% Klucel_ gel in ethanol, and 3% Klucel_ gel in ethanol (w/w). The receiver temperature was 37 °C. Samples from the receiver were collected at 2, 4, 6, 8, 12, 24, 30, 36, and 48 h and analysed by HPLC for concentrations of ATA and AT. The permeabilities of ATA through human cadaver skin were 1.0 × 10 – 4, 1.1 × 10 – 2, 1.4 × 10 – 4, 2.1 × 10 – 4, and 4.7 × 10 – 4 cm h–1 for the ethanol solution, isopropyl myristate solution, light mineral oil solution, 1% Klucel_ gel, and 3% Klucel_ gel, respectively. The results show that the formulation had relatively minor effects on the permeability coefficients of ATA through cadaver skin in all cases except for the isopropyl myristate solution.
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Document Type: Research Article
Publication date: August 1, 2005