Transdermal drug delivery method and system
The invention concerns a transdermal delivery system for controlled dispensing of an active substance to and through a porous surface. A certain amount of fluid comprising at least one active substance and at least one solvent is dispensed into an administration reservoir. In the administration reservoir the at least one solvent is separated from the administration reservoir by a solvent recovery means such that the active substance achieves a certain level on an interface device which is permeable for the one active substance. Thereby the active substance is absorbable via diffusion from the interface device by a porous surface to be treated.
1. A device for transdermal administration of an active substance, the device comprising:
a pressurized reservoir;
a solution of the active substance and a solvent disposed in the pressurized reservoir;
a porous skin interface adapted to receive solution from the reservoir and to transfer active substance to skin; and
a solvent recovery element communicating with the skin interface and adapted to receive evaporated solvent from the skin interface.
2. The device of claim 1 wherein the solvent recovery element comprises desiccant or absorbent material.
3. The device of claim 1 further comprising a vapor permeable material disposed between the skin interface and the solvent recovery element.
4. The device of claim 1 further comprising a piston disposed in the pressurized reservoir in contact with the solution.
5. The device of claim 1 further comprising a valve controlling flow of solution from the pressurized reservoir to the skin interface.
6. The device of claim 5 further comprising a programmable control unit adapted to control the valve.
7. The device of claim 1 wherein the skin interface comprises adhesive.
8. The device of claim 1 further comprising a housing into which the pressurized reservoir, porous skin interface and solvent recovery element are incorporated.
9. The device of claim 1 further comprising an administration reservoir adapted to receive the solution from the pressurized reservoir and to communicate with the porous skin interface.
10. A method for transdermally administering an active substance to a subject, the method comprising:
placing a porous skin interface of a transdermal dispensing system into contact with the subject's skin;
dispensing a solution of the active substance and a solvent from a pressurized reservoir of the dispensing system to the porous skin interface;
delivering the active substance through the porous skin interface to the subject's skin; and
moving solvent from the porous skin interface into a solvent recovery element of the dispensing system.
11. The method of claim 10 wherein the moving step comprises moving solvent into desiccant or an absorbent material of the solvent recovery element.
12. The method of claim 10 wherein the moving step comprises moving solvent through a vapor permeable material into the solvent recovery element.
13. The method of claim 10 wherein the dispensing step comprises moving a piston within the pressurized reservoir.
14. The method of claim 10 wherein the dispensing step comprises actuating a valve to control flow of solution from the pressurized reservoir to the skin interface.
15. The method of claim 14 wherein the actuating step comprises actuating the valve automatically according to a preset administration regime.
16. The method of claim 10 wherein the dispensing step comprises flowing the solution from the pressurized reservoir into an administration reservoir before reaching the porous skin interface.
17. The method of claim 10 further comprising adhesively attaching the dispensing system to the subject.