USP-5 Apparatus- Stainless Disk

The Pharma Alliance Group/Labecx Transdermal holder is a convenient disk assembly, recommended by the the FDA, for testing patch dosage forms in a standard dissolution test station for USP Apparatus 5"Paddle Over Disk". For use with standard USP 1 liter glass vessel and paddle.

Transdermal Patches

Although several apparatus and procedures have been used patches, it is desirable to avoid unnecessary proliferation of dissolution test equipment. Current compendial apparatus include the paddle over disk/disk assembly method (USP apparatus 5/PhEur2.9.4.1), the rotating cylinder (USP apparatus 6/Ph Eur 2.9.4.3), the reciprocating disk (USP apparatus 7), and a paddle over extraction cell method (Ph Eur 2.9.4.2). The paddle over disk procedure with a watch glass patch- screen sandwich assembly is considered to be the method of choice, as it has been shown experimentally that this procedure results in almost the same release profile as other, more complicated apparatus for all US-marketed transdermal patches.5 The configuration of this assembly ensures that the patch is prevented from floating during the testing period. Special attention needs to be given to the proper positioning of the patch so that the drug-loaded surface is exposed to the medium. The pH of the medium ideally should be adjusted to pH 5 to 6, reflecting physiological skin conditions. For the same reason, the test temperature is typically set at 32°C (even though the temperature may be higher when skin is covered). Ph Eur considers 100 rpm a typical agitation rate and also allows for testing an aliquot patch section. The latter may be an appropriate means of attaining sink conditions, provided that cutting a piece of the patch is validated to have no impact on the release mechanism.