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[0373] The cells were filled with DI water as a receiver solution. The DI water had been degased to remove air bubbles. The receiver solution was completely withdrawn and replaced with fresh DI water at each time point. The samples taken were analyzed by an HPLC for the concen› tration of oxytocin in the receiver solution. The cumulative amount of oxytocin across human cadaver skin was calcu› lated using the measured oxytocin concentrations in the receiver solutions for each time point, which were listed in Table 48. The skin was pretreated with 1 % NaOH for the specified pretreatment time period. 

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[0374] An in-vitro skin permeation study was conducted using four diclofenac sodium transdermal systems, desig› nated Diclo-1, Diclo-2, Diclo-3, and Diclo-4, the composi› tions of which are set forth in Table 49. Round disc samples were prepared as described in the Methods section. The theoretical percent weight for each ingredient after drying ( calculated assuming all the volatile ingredients were com› pletely removed during drying) is listed in Table 50. 

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[0375] 

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## Example 16 

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[0376] Since diclofenac sodium is not expected to react with NaOH, the NaOH concentration listed in Table 50 equals the excess NaOH concentration, calculated as described in Example 2. 

[0377] The pH of the patches was measured as described in the Methods section. The pH of the diclofenac sodium patch increased from 7.17 to 11.28 when the calculated excess NaOH concentration in the dried patch was increased from 0% to 3.6%. 

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[0378] The in vitro permeation of diclofenac sodium through human cadaver skin from these discs was measured as described in the Methods section. Three diffusion cells were used for each formulation. The cells were filled with 10% ethanol/90% water solution. The receiver solution was completely withdrawn and replaced with fresh ethanol/water solution at each time point. The samples taken were ana› lyzed by an HPLC for the concentration of diclofenac sodium in the receiver solution. The cumulative amount of diclofenac sodium across human cadaver skin was calcu› lated using the measured diclofenac sodium concentrations in the receiver solutions. 

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[0379] The cumulative amount of diclofenac sodium across human cadaver skin at 24 hours increased from 28.4 µg!cm 2 to 3647.3 µg/cm $^{2 }$when the calculated excess NaOH concentration in the dried patch was increased from 0% to 3.6%. The cumulative amount of diclofenac sodium across human cadaver skin at 24 hours from the system containing 1.3% NaOH (Diclo-2) was 2439.6 µg/cm 2 , which was about 85 times higher than that from the formulation without NaOH (28.4 µg/cm 2 , Diclo-1). 

