Nov. 4, 2004  34  US 2004/0220262 Al  TABLE 37  TABLE 38  TABLE  39  TABLE  40  µg/cm 2 )  with a calculated excess MgO concentration of  6.9% was slightly higher than that from the formulation  without MgO (Est-15, 0.32 µg/cm 2 ).  Thus, the formulation  of Est-16 provided up to 2-fold more estradiol flux than in  the absence of MgO (Est-15). This result indicated that MgO  enhances the permeation of estradiol.  [0358]  The cumulative amount of estradiol across human  cadaver skin at 24 hours decreased from 0.53 to 0.27  µg!cm 2  when the excess MgO concentration in the dried patch was  increased from 6.9% to 23.3%. This behavior may be  because the high concentration of MgO made the adhesive  matrix more hydrophobic and the amount of MgO that could  be dissolved by the small amount of water on the top of the  skin was reduced.  [0356]  The cumulative amount of estradiol across human  cadaver skin was calculated using the measured estradiol  concentrations in the receiver solutions.  [0359]  An in vitro skin permeation study was conducted  using four phenylpropanolamine hydrochloride transdermal  systems, designated PPA-17, PPA-18, PPA-19, and PPA-20,  the compositions of which are set forth in Table 39. The  matrix patches were prepared and evaluated using the same  procedures as set forth in Example 3. The theoretical percent  weight for each ingredient after drying ( calculated assuming  all the volatile ingredients were completely removed during  drying) is listed in Table 40.  Example 12  [0357]  The cumulative amount of estradiol that permeated  across the human cadaver skin at 24 hours for Est-16 (0.53  [0360]  Excess MgO Concentration  (wt  %) and pH  Est-15  Est-16  Est-17  Est-18  Excess MgO  0%  6.9%  16.9%  23.3%  Concentration  pH  7.48  8.95  9.66  10.28  Time  4.75 hours  15.75 hours  19.75 hours  23.75 hours  Cumulative Amount of Estradiol  (µg/cm 2 )  Est-15  0.08  0.21  0.26  0.32  Est-16  0.09  0.31  0.41  0.53  Est-17  0.05  0.19  0.26  0.36  Est-18  0.02  0.13  0.19  0.27  Component Weight and Weight Percent Based on Total Solution Weight  PPA-17  PPA-18  PPA-19  PPA-20  g(wt%)  g (wt%)  g(wt%)  g(wt%)  PPA-HCl  0.5 (6.9)  0.5 (6.0)  0.5 (5.9)  0.5 (5.7)  MgO  0  0.11 (1.3)  0.26 (3.1)  0.50 (5.7)  DI water  1.0 (13.9)  2.0 (24.0)  2.0 (23.6)  2.0 (22.9)  Methyl alcohol  0.5 (6.9)  0.5 (6.0)  0.5 (5.9)  0.5 (5.7)  PG  0.2 (2.8)  0.2 (2.4)  0.2 (2.4)  0.2 (2.3)  HPMC  0.02 (0.3)  0.02 (0.2)  0.02 (0.2)  0.02 (0.2)  PIE adhesive  4 (55.4)  4 (48.0)  4 (47.2)  4 (45.9)  (30% solid)  Heptane  1.0 (13.9)  1.0 (12.0)  1.0 (11.8)  1.0 (11.5)  Component Weight and Weight Percent Based on Dried Film Weight  PPA-17  PPA-18  PPA-19  PPA-20  g(wt%)  g(wt%)  g(wt%)  g(wt%)  PPA-HCl  0.5 (26.0)  0.5 (24.6)  0.5 (22.9)  0.5 (20.7)  MgO  0  0.11 (5.4)  0.26 (11.9)  0.50 (20.7)  PG  0.2 (10.4)  0.2 (9.9)  0.2 (9.2)  0.2 (8.3)  HPMC  0.02 (1.0)  0.02 (1.0)  0.02 (0.9)  0.02 (0.8)  PIE adhesive  1.2 (62.5)  1.2 (59.1)  1.2 (55.0)  1.2 (49.6) 