Claims for Patent: 4,379,454

Summary for Patent: 4,379,454

Title:	Dosage for coadministering drug and percutaneous absorption enhancer
Abstract:	A dosage form that coadministers a drug and a percutaneous absorption enhancer to a defined area of the skin. The dosage form comprises a body that contains supplies of drug and enhancer and has a basal surface that contacts the area of skin and transmits the drug and enhancer to the area for absorption thereby. The drug is provided to the basal surface at a rate at least as great as the rate at which the skin is able to absorb the drug whereas the enhancer is via a rate controlling means at a substantially constant rate that increases the permeability of the treated area of skin to the drug to a level at which the drug is absorbed at a therapeutically effective rate.
Inventor(s):	Campbell; Patricia S. (Palo Alto, CA), Chandrasekaran; Santosh K. (Palo Alto, CA)
Assignee:	ALZA Corporation (Palo Alto, CA)
Application Number:	06/235,068
Patent Claims:	1. A unit dosage form for coadministering a drug and a percutaneous absorption enhancer to a predetermined area of unbroken skin of a patient for a predetermined time period, the dosage form comprising a body (a) having a basal surface (i) of area at least about equal to the area of skin, (ii) that is adapted to contact the area of skin over the time period, and (iii) via which the drug and enhancer are presented to the area of skin for absorption thereby; (b) containing a supply of the drug that communicates with the basal surface to provide drug at the basal surface over the time period such that over a substantial portion of the time period the amount of drug provided is in excess of that which the area of skin is able to absorb; (c) containing a supply of the percutaneous absorption enhancer that communicates with the basal surface over said time period; and (d) including means for maintaining the rate at which the enhancer is provided at the basal surface substantially constant over a substantial portion of the time period, the rate being (i) below the maximum rate the area of skin is able to absorb, and (ii) sufficient to increase the permeability of the area of skin to the drug such that the drug is absorbed thereby at a rate that provides a therapeutically effective level of the drug in the bloodstream of the patient. 2. The unit dosage form of claim 1 wherein the basal surface is adhesive to the area of skin. 3. The unit dosage form of claim 1 wherein the supply of drug and the supply of enhancer are admixed and contained in a common reservoir. 4. The unit dosage form of claim 1 wherein the supply of drug and the supply of enhancer are maintained in separate reservoirs. 5. The unit dosage form of claim 1 wherein the means is a diffusion membrane positioned between the supply of enhancer and the basal surface through which the enhancer must permeate to reach the basal surface. 6. The unit dosage form of claim 1 wherein the rate at which the enhancer is provided at the basal surface is above that rate at which the rate of absorption of the drug by the area of skin ceases to increase significantly as the rate at which the enhancer is provided is increased. 7. A unit dosage form for coadministering a drug and a percutaneous absorption enhancer to a predetermined area of unbroken skin of a patient for a predetermined time period comprising a laminate body of: (a) a backing lamina that is substantially impermeable to drug and enhancer, one face of which defines the uppermost exterior surface of the body; (b) a reservoir lamina adjacent and below the opposite face that contains a supply of the drug and a supply of the enhancer; (c) a diffusion membrane lamina adjacent and below the reservoir lamina through which the drug and enhancer permeate; and (d) a contact adhesive lamina adjacent and below the reservoir lamina, one face of which defines a basal surface of the body that contacts and adheres to the area of skin over the time period, and through which the drug and enhancer permeate to the basal surface wherefrom they are absorbed by the area of skin, wherein the compositions and thicknesses of the diffusion membrane lamina and the contact adhesive lamina are such that (i) the drug permeates therethrough over the time period at a rate that provides the drug at the basal surface in excess of that which the area of skin is able to absorb; and (ii) the enhancer permeates therethrough at a substantially constant rate over a substantial portion of the time period, the substantially constant rate being below the maximum rate the area of skin is able to absorb and sufficient to increase the permeability of the area of skin to the drug such that the drug is absorbed by the area of skin at a rate that provides a therapeutically effective level of the drug in the bloodstream of the patient. 8. A dosage form for administering estradiol percutaneously and continuously over a predetermined time period through a predetermined area of unbroken skin of a woman to treat a condition caused by estradiol deficiency comprising a laminate body of: (a) a backing layer that is substantially impermeable to estradiol and ethanol, one face of which forms the top of the body; (b) a reservoir layer adjacent the opposite face of the backing layer comprising estradiol dispersed in gelled ethanol; (c) a diffusion membrane layer adjacent and below the reservoir layer through which estradiol and ethanol are released continuously over said predetermined time period from the reservoir after the body is affixed to the skin, the rate of estradiol release being at least as great as the rate at which said predetermined area of the skin is capable of absorbing estradiol, and the rate of ethanol release being substantially constant and in the range of 100 to 800 mcg/hr/cm.sup.2 of said area of skin; and (d) a contact adhesive layer adjacent and below the diffusion membrane layer, one face of which is the basal surface of the body when the body is affixed to the skin, the contact adhesive layer being permeable to estradiol and ethanol. 9. The dosage form of claim 8 wherein the edges of the backing layer and the diffusion membrane layer are sealed together so that the reservoir layer is wholly contained between the backing layer and the diffusion membrane layer. 10. The dosage form of claim 9 wherein the gelled ethanol contains about 5% to about 75% by weight of water. 11. The dosage form of claim 9 or 10 wherein the reservoir layer contains about 0.2 to 12 mg estradiol. 12. The dosage form of claim 9, 10, or 11 wherein the rate of ethanol release is in the range of 100 to 400 mcg/cm.sup.2 /hr. 13. A method for coadministering a drug and a percutaneous absorption enhancer to a predetermined area of unbroken skin of a patient for a predetermined time period comprising: (a) administering the drug to the area continuously over the time period such that over a substantial portion of the time period the amount of drug administered is in excess of that which the area of skin is able to absorb; and (b) simultaneously and continuously coadministering a percutaneous absorption enhancer to the area of skin at a rate that is substantially constant over a substantial protion of the time period, the rate being (i) below the maximum rate the area of skin is able to absorb, and (ii) sufficient to increase the permeability of the area of skin to the drug such that the drug is absorbed thereby at a rate that provides a therapeutically effective level of the drug in the bloodstream of the patient. 14. A method for treating a woman for a condition caused by estradiol deficiency comprising: (a) continuously administering estradiol to a predetermined area of unbroken skin of the said female over a predetermined time period with the rate of administration over a substantial portion of the time period being at least as great as the rate at which said area of skin is capable of absorbing estradiol; and (b) simultaneously and continuously coadministering ethanol to the area of skin at a substantially constant rate in the range of 100 to 800 mcg/hr/cm.sup.2 of said area of skin over a substantial portion of the time period. 15. The method of claim 14 wherein the area of skin is about 5 to 20 cm.sup.2. 16. The method of claims 14 or 15 wherein said substantially constant rate is in the range of 100 to 400 mcg/cm.sup.2 /hr.