|Title:|| Subsaturated transdermal therapeutic system having improved release characteristics|
|Abstract:||Rate controlled transdermal delivery devices are disclosed which utilize an in-line adhesive to maintain the device on the skin and deliver an agent which is a solvent or a plasticizer for the in-line adhesive. The initial equilibrated concentration of the agent in the agent reservoir and the adhesive is below saturation, and the reservoir comprises the agent dissolved in a solvent with respect to which the rate controlling element of the device is substantially impermeable. In preferred embodiments the initial loading of the agent in reservoir is sufficient to prevent the activity of the agent in the reservoir from decreasing by more than about 50% and preferably no more than about 25% during the predetermined period of administration: and the thicknesses of the adhesive, rate controlling membrane and reservoir layers are selected so that at least 50% and preferably at least 75% initial equilibrated agent loading is in the reservoir layer. The devices are usable to deliver agents which are liquid at body temperatures such as benztropine, secoverine, nicotine, arecoline, polyethylene glycol monolaurate, glycerol monolaurate, glycerol monooleate and ethanol, for example.|
|Inventor(s):|| Enscore; David J. (Sunnyvale, CA), Campbell; Patricia S. (Palo Alto, CA), Osborne; James L. (Mountain View, CA), Smart; Melinda K. (Sunnyvale, CA), Yum; Su I. (Los Altos, CA) |
|Assignee:|| Alza Corporation (Palo Alto, CA) |
1. In a transdermal delivery device for administering an agent through the skin of a subject over a predetermined administration period, said device comprising an agent reservoir having
an agent which is a solvent for medically acceptable adhesives dissolved therein at a concentration less than saturation, said reservoir being maintained in drug transmitting contact with the skin by means of the adhesive properties of the agent
releasing surface of said device; the improvement wherein said agent is dissolved in said reservoir at:
a) concentration less than saturation and at an activity that is less than that at which said adhesive surface loses its adhesive properties; and
b) an initial equilibrated agent loading that is sufficient to prevent the activity of said agent in said reservoir from decreasing by more than 75% during said administration period.
2. The device of claim 1 where n at least 50% of the initial loading of the agent in the device is in the agent reservoir.
3. The device of claim 1 wherein said decrease in activity is no greater than 25%.
4. The device of claim 1 wherein at least 50% of the initial loading of the agent in the device is in the agent reservoir.
5. The device of claim 1 wherein said decrease in activity is no greatr than 25%.
6. The device of claim 1 wherein at least 75% of the initial agent loading is in the reservoir.
7. The device of claim 1 wherein said agent is an oily, nonpolar material, liquid at body temperature.
8. The device of claim 1 wherein said reservoir contains more than one agent at least one of which is an oily, nonpolar material, liquid at body temperature.
9. The device of claim 1 wherein said agent solubilizes said adhesive.
10. The device of claim 1 wherein said agent plasticizes said adhesive.