2.6.4. In Vitro Release

In vitro KET release, from ZnAl-KET and ZnAl-KET dispersed in the patch, was evaluated by dissolution testing for transdermal patches according to the European Pharmacopoeia (Ph. Eur. 10th

Ed.). Precisely, the apparatus II of the dissolution test was used, positioning an extraction cell (Ph. Eur. 10th Ed.) at the bottom of the vessel.

The central part of the cell formed a cavity (depth of 2.6 mm, diameter 27.0 mm) to hold the patch. On the top of the cell was positioned a cover with a central opening of 20.0 mm obtaining a release surface of 3.14 cm2. The cell was positioned at the bottom of the vessel with the cover facing upwards and at a distance of 25.0 ± 2.0 mm from the paddle blade. The test was carried out for 24 h by working at 40 rpm at 32.0 ± 0.5 ◦C in sink conditions and using phosphate buffer pH 5.50 (Ph. Eur. 10th Ed.) as a dissolution medium (400 mL). At predetermined intervals, 2 mL of sample was withdrawn from the vessel and replaced by the same amount of fresh dissolution medium.
