Transdermal drug delivery system

Claim 1

A transdermal drug delivery system for administering a drug, chemically identifiable as (1a,2,3,4a,5,6-hexahydro-9-hydroxy-4-propyl-4H-naphth[1,2-b]-1,-oxazine, over an extended period comprising, (a) a backing layer substantially impermeable to the drug and forming the top or outer surface of a bandage employing the delivery system, (b) a resevoir layer comprising drug in a completely dissolved form in a continuous matrix of a carrier, (c) a membrane layer comprising a structure exhibiting some rate controlling property, wherein a substantially constant release rate is achieved over a substantial part of the wear period by the combined action of the reservoir layer and the membrane layer wherein: ##EQU9## are satisfied simultaneously, and wherein: h is membrane thickness K is partition coefficient between membrane and reservoir D m is diffusion coefficient of drug in membrane x max is reservoir thickness D r is diffusion coefficient of drug in reservoir T is the desired wear time of the bandage, α is a design parameter ranging from but not including 0 to and including 0.67, and representing the fractional drop in the theoretical flux from time zero to the end of the wear period T and β is a design parameter ranging from but not including 0 to and including 1, which allows adjustments to shape of release profile, initial concentration, C o , fraction of total drug depleted from the reservoir, h and x max ; and ≧ signifies equal to or greater than.