| abstract |
A transdermal delivery system (1,11) for the transdermal administration of a drug hasn (a) a backing (2,12) that is substantially impermeable to the drug, (b) a matrix (3,13), adjacent to a surface of the backing, the matrix containing a gel comprising a hydrophilic fluid, a fluid gelling agent and the drug, and (c) a perforated sheet (4,14), adjacent to the matrix, that allows passage of the drug containing gel through its perforations. nPreferably the system also has a contact adhesive layer (5,15) and a protecting layer (6,16). n The long term adhesion of the delivery system to a patient may be effected by forming a channel (17), surrounding the matrix, in the perforated sheet/contact adhesive layer lamina. The channel inhibits the lateral movement of the drug containing gel. Furthermore, by forming a weak seal (18) in the matrix surrounding channel, the loss of a volatile drug from the gel may also be prevented. |