peak areas of C-H stretching absorbances in comparison with untreated SC. Depilatory lotion treatment also decreased (P < .05) the epidermal resistance in comparison with the control epidermis. The decrease in the α-helix conformation and the increase in the random and turn structures were observed in the SC proteins due to depilatory lotion treatment. The changes in the secondary structure of proteins and lipid extraction from the SC are suggested as the cause of the decrease in the epidermal resistance and the increase in the passive and iontophoretic permeability of insulin through depilatory-pretreated epidermis in comparison with the control epidermis.The effect of thioglycolate-based depilatory lotions was studied on the in vitro passive and iontophoretic permeability of insulin through porcine epidermis and biophysical changes in the stratum corneum (SC) lipids and proteins. The porcine epidermis and Franz diffusion cells modified for iontophoresis were used for the in vitro transport studies. Cathodal iontophoresis was performed at 0.2 mA/cm 2 current density. Resistance of the control-and depilatory-lotion-treated epidermis was determined according to Ohm's law. Biophysical changes were studied on porcine SC before (control) and after treatment with the depilatory lotions using Fourier transform infrared (FT-IR) spectroscopy. Asymmetric (~2915 cm -1 ) and symmetric (~2848 cm -1 ) Carbon-Hydrogen (C-H) stretching absorbances were studied to estimate the extent of lipid extraction. Fourier self-deconvolution and second derivative procedures were applied to amide I band (1700-1600 cm -1 ) in order to estimate quantitatively the changes in the secondary structure of the SC protein. The passive permeability of insulin was significantly (P < .05) increased through depilatory-lotion-treated (ie, Better Off, Marzena, and Sally Hansen) epidermis in comparison to control. Iontophoresis significantly enhanced (P < .05) the permeability of insulin through depilatory-pretreated epidermis in comparison with the control epidermis. Further, we were able to achieve the desired flux of insulin (5.25 U/cm 2 /d) through Better Off-treated epidermis using 0.2 mA/cm 2 current density and 100 U/mL donor concentration of insulin. The SC treated with depilatory lotions showed a decrease in

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The purpose of this study was to investigate the effect of chemical enhancers (fatty acids and limonene) and iontophoresis on the in vitro permeability enhancement of insulin through porcine epidermis. The following fatty acids were used: palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), and linolenic (C18:3). Franz diffusion cells and the Scepter iontophoretic power source were used for the percutaneous absorption studies. Cathodal iontophoresis was performed at 0.2 mA/cm2 current density. Iontophoresis in combination with chemical enhancers synergistically increased (p<0.05) the in vitro permeability of insulin. Linolenic acid (C18:3) produced greater permeability of insulin through epidermis than did other fatty acids during passive (44.45 x 10(-4) cm/h) and iontophoretic (78.03 x 10(-4) cm/h) transport. Lispro insulin flux was significantly (p<0.05) greater through linolenic acid and limonene pretreated epidermis compared to untreated controls during both passive and iontophoretic transports. Using limonene as a penetration enhancer, a linear increase in the passive and iontophoretic flux of lispro insulin was observed with donor concentrations increasing from 100 IU/mL to 300 IU/mL. Iontophoretic flux through limonene-treated epidermis using 0.5 mA/cm2 current density and 300 IU/mL insulin donor solution was 45.63 IU/cm2/day. Using an iontophoretic patch size of 10 cm2, we would be able to deliver 50 IU of insulin within 3 h.

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The effect of chemical enhancers (e.g., fatty acids, limonene, depilatory lotions) and iontophoresis was investigated on the in vitro permeability of leuprolide acetate through porcine epidermis. Franz diffusion cells and Scepter iontophoretic power source were used for the percutaneous absorption studies. Anodal iontophoresis was performed at 0.2 mA/cm2 current density. Fatty acids used were palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), and linolenic (C18:3) acids. The passive and iontophoretic flux were significantly (p < 0.05) greater through fatty acids-treated porcine epidermis in comparison to the control (untreated epidermis) for leuprolide acetate. The passive and iontophoretic permeability of leuprolide acetate increased with increasing number of cis double bonds. Among the fatty acids tested, linolenic acid (C18:3) exhibited the maximum permeability of leuprolide acetate during passive (51.42 x 10(-4) cm/hr) and iontophoretic (318.98 x 10(-4) cm/hr) transport. The passive and iontophoretic flux of leuprolide acetate were significantly (p < 0.05) greater through the limonene and depilatory lotion treated epidermis in comparison to their respective control. In conclusion, iontophoresis in combination with chemical enhancers synergistically increased (p < 0.05) the in vitro permeability of leuprolide acetate through porcine epidermis.