Method and apparatus for enhancement of transdermal transport
According to the present invention, a method for enhancing transdermal transport is disclosed. The method includes the steps of increasing a permeability of an area of a membrane with a permeabilizing device. The membrane may be, inter alia, biologic skin or synthetic skin. The permeabilizing device may be an ultrasound-producing device. A substance is transported into and through the area of the membrane. The substance may be a drug, a vaccine, or a component of interstitial fluid.
1. A method for enhancing a permeability of an area of skin for drug delivery or analyte extraction comprising:
increasing the permeability of the area of skin with a skin permeabilizing device, wherein the skin permeabilizing device comprises a permeability monitoring circuit for monitoring at least one electrical parameter of the area of skin indicative of skin permeability and wherein the skin permeabilizing device permeabilizes the skin using mechanical force;
applying electricity in the form of an alternating current to the area of skin;
monitoring the at least one electrical parameter of the area of skin using the permeability monitoring circuit of the skin permeabilizing device; and
controlling the mechanical force applied to the area of skin by the skin permeabilizing device based on the at least one electrical parameter,
wherein after the permeability of the skin is increased, the analyte or drug is able to passively diffuse through the skin.
2. The method of claim 1 , further comprising:
applying electricity to the area of skin before increasing the permeability of the area of skin with a skin permeabilizing device; and
measuring a baseline for the at least one electrical parameter.
3. The method of claim 1 , further comprising:
coupling a first electrode with the area of skin;
coupling a second electrode with the area of skin; and
measuring the at least one electrical parameter using the first electrode and the second electrode.
4. The method of claim 3 , wherein the first electrode is coupled with a portion of stratum corneum of the area of skin.
5. The method of claim 4 , wherein the second electrode is coupled with a portion of epidermis over which the stratum corneum has been removed.
6. The method of claim 4 , wherein the second electrode is coupled with a portion of stratum corneum of the skin.
7. The method of claim 3 , wherein at least one of the first and second electrode is coupled through a conductive medium.
8. The method of claim 7 , wherein the conductive medium is a gel.
9. The method of claim 7 , wherein the conductive medium is a liquid.
10. The method of claim 3 , wherein the second electrode is placed on the skin.
11. The method of claim 1 , further comprising:
comparing the at least one electrical parameter with a baseline, and
wherein the step of controlling the skin permeabilizing device comprises discontinuing the application of the skin permeabilizing device based on the comparison.
12. The method of claim 1 , wherein the electrical parameter is selected from the group consisting of impedance, conductance, capacitance, current, and voltage.
13. The method of claim 1 , wherein said application of said skin permeabilizing device is continuous.
14. The method of claim 1 , wherein said application of said skin permeabilizing device is discontinuous.
15. The method of claim 14 , further comprising the steps of
performing analog to digital conversion on said information on a time-variation of skin conductance; and
filtering said digital data.
16. The method of claim 1 , further comprising a step of processing data from the monitoring step to establish information on a time-variation of skin conductance.
17. The method of claim 16 , wherein the step of processing comprises fitting said information into the following equation:
C
=
C
i
+
(
C
f
-
C
i
)
1
+
ⅇ
S
(
t
-
t
*
)
where:
C is current;
C i is current at t=0;
C f is the final current;
S is a sensitivity constant;
t* is the exposure time required to achieve an inflection point; and
t is the time of exposure.
18. An apparatus for enhancing permeability of an area of skin comprising:
a skin permeabilizing device configured to increase a permeability of the area of skin using mechanical force;
an electrical source operable to apply electricity in the form of an alternating current to the area of skin;
a permeability monitoring circuit to monitor at least one electrical parameter of the area of skin indicative of skin permeability; and
a controller responsive to the permeability monitoring circuit and operable to control the mechanical force applied to the area of the skin by the skin permeabilizing device based on the at least one electrical parameter of the area of skin.
19. The apparatus of claim 18 , wherein the electrical source comprises:
a first source having a first frequency; and
a second source having a second frequency.
20. The apparatus of claim 19 , wherein the circuit measures the at least one electrical parameter of the area of skin at the first frequency and at the second frequency.
21. The apparatus of claim 18 , further comprising:
a first electrode, wherein in use the first electrode is coupled on the area of skin; and
a second electrode, wherein in use the second electrode is positioned on the skin;
wherein in use the circuit measures the at least one electrical parameter of the area of skin between the first electrode and the second electrode.
22. The apparatus of claim 18 , wherein the parameter is selected from the group consisting of impedance, conductance, capacitance, current, and voltage.