Transdermal drug delivery system

Claim 1

An electro-osmotic transdermal drug delivery system for passing at least one drug for delivery to the systemic blood of a patient through the skin (16) having a plurality of sweat and sebaceous shunt ducts (30) opening at the surface of the stratum corneum (28), comprising, in combination, drug storage means positioned in juxtaposition with the skin (16) of the patient, said drug storage means being for holding an electrolytic liquid (24) contain­ing the at least one drug, power means for generating first and second electrical currents, said first electrical current being rela­tively high as compared to electrical current in electro-osmotic drug delivery systems, said second electrical current being greater than said first electrical current, circuit means for connecting said power means with said drug storage means and with the skin (16), the electrolytic liquid (24) containing the at least one drug being moved along with said first electrical current by electro-osmotic motion into the skin (16), said drug storage means including liquid-movement-­inhibiting means for slowing the movement of the electrolytic liquid to said shunt ducts (30) thus inhibiting refilling of said shunt ducts (30) with the electrolytic liquid (24) so that said first electri­cal current and the electrolytic liquid (24) with the at least one drug bypasses the shunt ducts (30) and is directed into the skin (16) by way of the stratum corneum (28) said first electrical current being such that when combined with said liquid-move­ ment-inhibiting means the shunt ducts (30) are re­plenished with the electrolytic liquid (24) at perio­dic time intervals so that said second electrical current is drawn away from said stratum corneum (28) to said replenished shunt ducts (30) at which time said shunt ducts (30) are emptied of said electro­lytic liquid (24) as a result of the passage of said first electrical current, whereby the shunt ducts (30) are emptied of the electro­lytic liquid (24) by the combination of the effect of said liquid-movement-inhibiting means, said first electrical current, and said electrical current, at said relatively long periodic time intervals.

Claim 5

The system according to one of the claims 1 to 3, wherein said drug storage means includes an under­surface in general contact with the skin (16) of the patient, and said drug storage means includes a layer (67) made of a hydrophobic material applied to said undersurface, said layer limiting the move­ment of water from said drug storage means, so that the shunt ducts (30) are generally devoid of liquid.

Claim 9

The system according to one of the preceding claims, wherein said first current is a selected current such that when combined with said liquid-movement-­inhibiting means the shunt ducts (30) replenish with said liquid at periodic time intervals, said shunt ducts (30) being thereupon emptied of said liquid by the combination of the effect of said liquid-­movement-inhibiting means and said selected current at periodic intervals.

Claim 10

The system according to one of the preceding claims, further including current conditioner means positioned in series with said circuit means for producing said second electrical current at said periodic time inter­vals, said periodic time intervals being relatively long periodic time intervals as compared to periodic time intervals generally used in the art of current conditioners, said increased level of current accelerat­ing the emptying said shunt ducts (30) of said liquid at said periodic time intervals.

Claim 12

The system according to one of the preceding claims, wherein said relatively long periodic time intervals are in the range of a number of minutes to a number of hours.

Claim 13

The system according to one of the claims 9 to 11, wherein said current conditioning means is a current conditioner.

Claim 14

The system according to one of the claims 9 to 12, wherein said current conditioning means is an oscill­ator (68).

Claim 15

The system according to one of the claims 2 to 13, wherein said semi-permeable membrane (64) has an undersurface facing the stratum corneum (28), sand said liquid-movement-inhibiting means further includes a water repellent layer (67) applied to said under­surface, said water repellent layer (67) inhibiting any movement of the electrolytic liquid from said semi-permeable membrane (64) to the shunt ducts (30).

Claim 20

The system according to one of the preceding claims, wherein said liquid-movement-inhibiting means includes said drug storage means being made of a uniform aniso­tropic hydrogel (48) of a semi-dry consistency which limits the amount of the electrolytic liquid which said hydrogel can pass through the shunt ducts (30) so that the shunt ducts (30) do not pass said first electrical current from said drug reservoir.