For the in vitro skin permeation experiments, the effects of FFP, PE, and DE concentration and the screened PE content on skin permeation were investigated to optimize the DE MTDS formulation. The results of F1 to 4 were shown in

Figure 1, and the control group was F9 described in Table 1. In order to confirm the permeation enhancement of the ethanol evaporation, we added the pure drug group, which meant that the equal amount of drug to other groups was uniformly put on the skin. The transdermal permeation profiles of formulations containing different FFPs did not show significant difference. The formulation including FFP reduced the permeation of DE Inhibitors,research,lifescience,medical significantly compared with the control group, indicating that the FFP would inhibit the transdermal delivery of DE. The significant difference between the control

and pure drug group, indicating the evaporation of ethanol, would enhance the permeation Inhibitors,research,lifescience,medical effect. Figure 1 Percutaneous permeation profiles of DE MTDS containing different film forming polymers (mean ± SD; n = 3). The results of F5 to 8 were shown in Figure 2. The control and pure drug group was the same as the one in Figure 1. As seen from the figure, the transdermal flux of them was LA > IPM > AZO > PG. LA and IPM showed comparable transdermal Inhibitors,research,lifescience,medical flux without significant difference at this concentration level. Though PG had the greatest solubility for DE, its transdermal flux was the lowest. This might attribute to the fact proven by Trottet that PG would permeate through the skin and might carry the drug with it, as shown by correlations Inhibitors,research,lifescience,medical in vitro between the permeation of both PG and the drug [28]. As the PG permeated through the skin, the “drug reservoir” in the skin would not be formed. Besides, the investigation of influence Inhibitors,research,lifescience,medical of penetration enhancer on drug permeation from volatile formulations by Hadgraft reconfirmed the

conclusion stated by Trottet. In addition, Hadgraft presented that, after administration, IPM remained in the skin to form a “patchless drug reservoir” instead of permeating through the skin like PG did [29]. The AZO group showed a relatively low selleck chemicals tansdermal flux compared with the IPM and LA group; to some extent, it indicated that the solubility of DE in PE was a critical fact determining the transdermal flux [30, 31]. The transdermal flux of the control group is much higher compared with the group containing pure drug. This might attribute to the fact that the evaporation these of ethanol could increase the thermodynamic energy of drug. Besides, ethanol also can be used as permeation enhancer in some cases [32]. Figure 2 Percutaneous permeation profiles of dexketoprofen MTDS containing different penetration enhancers (mean ± SD; n = 3). As the results shown in Figure 1, we can see that the transdermal flux of the formulations incorporating different FFPs did not show significant difference.