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9. Evaluation of adhesive properties (Probe Tack test)

▪ The tip of a clean probe with a defined surface roughness is brought into contact with
adhesive and when a bond is formed between probe and adhesive, the subsequent removal
of the probe mechanically breaks it.

▪ The force required to pull the probe away from the adhesive at fixed rate is recorded as tack
and it is expressed in grams.

10. Release performance

10.1. In Vitro Drug Release Studies

▪ The test provides the estimate of drug that is released from the patch within a specific time
and under controlled conditions.

▪ The United States Pharmacopoeia (USP) dissolution
apparatus five (Paddle over disks apparatus) is used to
determine the release of drugs from patches.

▪ The patch is stacked to the stainless disk; (the release surface
is in contact with the release medium)

▪ Then the disk was submerged in a medium. The paddle is
positioned over the disk at a distance of 2.5 cm and rotated at
a predetermined speed

▪ The aliquots can be removed at appropriate time intervals and analyzed by suitable method

10.2. Ex Vivo Skin Permeation Studies

▪ The skin permeation is simulated in the ex vivo skin permeation evaluation
using diffusion cell.

▪ The Franz diffusion cell has a donor compartment (housed a formulation
under test) and receiver (containing dissolution media) compartment, and in
between them an excised and cleaned full-length rat skin (or human
cadaver skin if available) is placed facing its dermal face to the donor
compartment.

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