Patch Drug Delivery allows for pharmaceuticals to be delivered across the skin barrier and into systemic blood circulation. This type of delivery helps bypass initial metabolism in the liver and the gastrointestinal tract that occurs with oral medications.

Early transdermal drug delivery patches launched in the 1980's were of a liquid reservoir type design. In this configuration, the drug is dissolved in a liquid reservoir vehicle, often alcohol based, which is separated from the skin by a semi-permeable membrane and contact adhesive.

In the 1990's, technology improvements led to the development of the matrix-type patch, which integrates the active drug, skin permeability enhancer, and adhesive into one "membrane-like" layer coated onto a flexible protective backing film. The matrix system makes the patch thinner, more comfortable, more discreet, provides for better adhesion, and is less prone to causing skin irritation.(1) In addition, matrix systems are not dependent upon the finite volume of alcohol based liquid reservoirs and provide for more consistent delivery of the drug over the dosing interval.(2)

(1) R.S. Berger, G.D. Cioppa, and C.O. Dillard, Skin Tolerability and Adhesion Characteristics of a New Matrix Patch and a Marketed Reservoir Patch for Estradiol Delivery. Menopause. Vol. 4(1), 1997, 46-51.

(2) A.J. Bowen, V.A. John, M.E. Ramirez, and W.R. Good, Bioavailability of Oestradiol from the AloraTM (0.1 mg/day) Oestradiol Matrix Transdermal Delivery System Compared with Estraderm® (0.1 mg/day). J Obstet & Gynocol. Vol. 18(6), 1998, 577-582.