Skin penetrating abilities and reservoir effects of neat DMF and DMF/water mixtures
2009
Wang, Shimin | Chang, Ho-Yuan | Tsai, Jui-Chen | Lin, Wei-Chao | Shih, Tung-Sheng | Tsai, Perng-Jy
This study was set out to determine the skin permeabilities of neat N, N-dimethylformamide (DMF, denoted as DMF₁₀₀%) and DMF/water mixtures (including 50% DMF/50% water and 10% DMF/90% water mixtures (v/v), denoted as DMF₅₀% and DMF₁₀%, respectively) and to assess their skin reservoir effects on the systemic absorption. The penetration fluxes for DMF₁₀% and DMF₅₀% (=0.015 and 0.126mg/cm²/h, respectively) were only ~1.1%and 15% in magnitude as that of DMF₁₀₀% (=0.872±0.231mg/cm²/h), respectively. The above results could be because the perturbation effect of the DMF content was much more significant than the rehydration effect of the water content on skin permeability. We found that 85.9%, 96.6% and 98.7% of applied doses were still remaining on the skin surface, 4.98%, 0.838% and 0.181% were still remaining in the skin layer, and 9.09%, 2.61% and 1.17% penetrated through the skin layer after the 24-h exposure for DMF₁₀₀%, DMF₅₀% and DMF₁₀%, respectively. We found that the half-life (T ₁/₂) of DMF retaining in the skin layer were 12.3, 4.07 and 1.24h for DMF₁₀₀%, DMF₅₀% and DMF₁₀%, respectively. The estimated reservoir effect for DMF₁₀₀% (= 34.1%) was higher than that of DMF₅₀% and DMF₁₀% (=27.1% and 14.1%, respectively). The above results suggest that the impact associated with the internal burden of DMF could be prolonged even the external exposure of DMF is terminated, particularly for those dermal contact with DMF/water mixtures with high DMF contents.
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