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[0395] 

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[0396] Since diclofenac sodium is not expected to react with NaOH, the NaOH concentration listed in Table 61 equals the excess NaOH concentration, calculated as described in Example 2. 

[0397] The pHs of the receiver solutions at various time points are listed below. 

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[0398] The pH of the patches was measured as described in the Methods section. The pH of the diclofenac sodium patch increased from 7.40 to 10.38 when the calculated excess NaOH concentration in the dried patch was increased from 0% to 1.8%. 

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[0399] The in vitro permeation of diclofenac sodium through human cadaver skin from these discs was measured 

as described in the Methods section. Twelve diffusion cells were used for each formulation. The cells were filled with 10% ethanol/90% water solution. At each time point, the pH at the interface between skin and the patch for three diffusion cells was measured by removing the receiving fluid, remov› ing the clamp and the donor chamber, gently teasing the patch away from the skin with tweezers, leaving the skin on the receiver chamber, measuring the pH of the solution on the skin by placing the microelectrode directly onto the skin surface. 

[0400] The cumulative amount of diclofenac sodium across human cadaver skin was calculated using the mea› sured diclofenac sodium concentrations in the receiver solu› tions. 

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[0401] The cumulative amount of diclofenac sodium across human cadaver skin at 24 hours increased from 34.6 µg!cm 2 to 3257.7 µg/cm $^{2 }$when the calculated excess NaOH concentration in the dried patch was increased from 0% to 1.8%. The cumulative amount of diclofenac sodium across human cadaver skin at 24 hours from the system containing 0.4% NaOH (Diclo-10) was 227.7 µg/cm 2 , which was about six times higher than that from the formulation without NaOH (34.6 µg!cm 2 , Diclo-9). This result indicated that the 

