Method and apparatus for determination of chemical species in body fluid

We claim:

1. A dermal concentration patch for determining the presence of an analyte in a subject mammal's perspiration, comprising:

a water permeable support layer having a first and a second side;

at least one first and at least one second reagent immobilized in the support layer; and

means for removably securing the first side of the support layer in fluid communication with the subject's skin, wherein said patch is water permeable so that water vapor is permitted to escape through the support layer and outside of the concentration patch, and wherein the first reagent comprises a specific binding partner for the analyte to be determined, and the second reagent comprises a specific binding partner for a reference substituent in the perspiration.

2. A dermal concentration patch as in claim 1, wherein the first and second reagents are contained in discrete regions on the patch.

3. A dermal concentration patch as in claim 1, wherein the means for securing comprises adhesive tape.

4. A method of detecting false negative results in an assay of a body fluid from a subject which are the result of noncompliance with the testing procedure by the subject, comprising the steps of:

securing a test patch to the subject in communication with a source of body fluid, the test patch comprising first detection chemistry for detecting the presence of an analyte in the body fluid and second detection chemistry for detecting the presence of a reference substituent in the body fluid;

removing the test patch from the subject after a sufficient test period of time to enable the first detection chemistry to detect the analyte, if present;

determining the amount of reference substituent detected by the second detection chemistry; and

comparing the amount of reference substituent detected to a predetermined value to determine whether the test patch remained secured to the subject for substantially all of the test period of time.

5. A method of detecting false negative results as in claim 4, further comprising the step of determining whether any analyte was detected by the first detection chemistry.

6. A method of detecting false negative results as in claim 4, wherein the analyte to be detected by the first detection chemistry comprises a drug of abuse or its metabolite.

7. A dermal concentration patch for determining the presence of an analyte in a subject mammal's perspiration, in which false negative results produced through elution of the patch with a solvent can be detected, comprising:

a water permeable support layer having a first side and a second side, said first side being applicable to the subject's skin;

means for removably securing the first side of the support layer in fluid communication with the subject's skin; and

a soluble marker within the support layer, the presence of which can be detected after the patch is removed,

said patch having sufficient permeability to allow water to escape said patch in the vapor phase, wherein a substantial loss in the quantity of soluble marker present in the patch after the patch is removed is indicative of false negative results.

8. The dermal concentration patch of claim 7, wherein the marker is soluble in non-aqueous solvents.

9. The dermal concentration patch of claim 7, wherein the marker is a visible marker which will not cause significant trauma to the skin upon prolonged skin contact and is not readily absorbed by the skin.

10. A method of detecting false negative results in an assay for an analyte in a body fluid from a subject which are the result of elution of a test patch with a solvent, comprising the steps of:

securing the test patch to the subject in communication with a source of body fluid, the test patch containing a marker soluble in the solvent used for elution;

removing the test patch from the subject after a sufficient test period of time to enable the analyte to be detected by an assay for the analyte;

determining the amount of marker remaining in the test patch; and

comparing the amount of marker remaining in the test patch with a control, the control being the amount of marker empirically determined to be remaining in a test patch worn continuously by a subject for the same length of time,

wherein an amount of marker remaining in the test patch lower than the control is indicative of false results.

11. The method of claim 10, wherein the control is assumed to be substantially all the marker remaining in the patch.

12. The method of claim 11, wherein the marker comprises a visible dye and the comparing step comprises comparing the color of the test patch after removal of the patch to the color of a test patch before application.

13. A dermal concentration patch for determining the presence of an analyte in a subject mammal's perspiration, in which false negative results produced through the addition of adulterants to the patch can be detected, comprising:

a water permeable support layer having a first side being applicable to the subject's skin;

means for removably securing the first side of the support layer in fluid communication with the subject's skin; and

a test region on said patch for detecting the presence of an adulterant capable of producing false negative results in an assay for the analyte, wherein the test region comprises color change chemistry responsive to the presence of an adulterant selected from the group consisting of: aluminum, chromate, cobalt, copper, iron, nickel, nitrate, peroxide, sulphite, tin, calcium, high pH, low pH, glucose, protein, and ketones,

wherein water is permitted to escape through the support layer and outside of said concentration patch.

14. A method of detecting false negative results in an analyte binding assay of a body fluid from a subject which are the result of the addition of an adulterant to a test patch, comprising the steps of:

securing said test patch to the subject in communication with the source of said body fluid, said test patch comprising a test strip capable of detecting the adulterant by the development of a detectable change on the strip;

removing said test patch from the subject after a sufficient test period of time to enable an analyte to be detected by an assay for said analyte; and

determining the presence of adulterant from the presence of the detectable change on the test strip.

15. The method of claim 14, wherein the detectable change is a color change.

16. The method of claim 14, wherein the adulterant is selected from the group consisting of: aluminum, ammonium, chromate, chlorine, cobalt, copper, ion, nickel, nitrate, peroxide, sulphite, tin, calcium, high pH, low pH, glucose, protein, and ketones.

17. A method of detecting false negative results in an assay for an analyte in perspiration from a subject having skin, said negative results being the result of noncompliance with a testing procedure for said assay, comprising the steps of:

securing a test patch to the subject in fluid communication with the skin of said subject, said test patch comprising detection chemistry for detecting a reference substituent from perspiration;

accumulating perspiration in said test patch;

removing the test patch from the skin of said subject after sufficient test period of time to allow a detectable amount of said analyte to accumulate in said test patch if the analyte is present in said perspiration;

determining the amount of reference substituent detected by said reference substituent; and

comparing the amount of reference substituent detected to a predetermined value to determine whether the test patch was removed at a time after the securing step and before the removing step.

18. The method of claim 17, further comprising the step of determining whether analyte is present in said test patch after the accumulating step.

19. The method of claim 17, wherein said analyte comprises a drug of abuse or its metabolite.

20. The method of claim 17, wherein water is permitted to escape the test patch.

21. The method of claim 20, wherein water is permitted to escape the test patch in the vapor phase, but not in the liquid phase.

22. A dermal concentration patch for determining the presence of an analyte in a subject mammal's perspiration, comprising:

a water permeable support layer having a first and a second side;

a permeable outer protective layer disposed adjacent the second side of said support layer;

at least one first and at least one second reagent immobilized in the support layer; and

means for removably securing the first side of the support layer in fluid communication with the subject's skin,

wherein water is permitted to escape through the support layer and outside of the concentration patch, and wherein the first reagent comprises a specific binding partner for the analyte to be determined, and the second reagent comprises a specific binding partner for a reference substituent in the perspiration.

23. A dermal concentration patch for determining the presence of an analyte in a subject mammal's perspiration, comprising:

a water permeable support layer having a first and a second side;

at least one first and at least one second reagent immobilized in the support layer;

wherein the first reagent is a specific binding partner for a drug of abuse or its metabolite; and

means for removably securing the first side of the support layer in fluid communication with the subject's skin,

wherein water is permitted to escape through the support layer and outside of the concentration patch the first reagent comprises binding partner for the analyte to be determined, and the second reagent comprises a specific binding partner for a reference substituent in the perspiration.

24. A dermal patch for the non-invasive determination of at least one preselected low-concentration analyte in a body fluid expressed through the skin as perspiration without the need for conventional instrumentation, comprising:

a water-permeable support layer for concentrating components of perspiration, said layer having a single reference zone and at least two analyte detection zones;

at least one analyte detection reagent immobilized to each of said analyte detection zones for detecting the presence of the at least one analyte;

at least one reference detection reagent immobilized to each of said reference zones for detecting the presence of a reference substituent known to be present in perspiration;

the analyte detection reagent in at least one of the analyte detection zones comprising an antibody having an affinity for a drug of abuse or a metabolite thereof cable of passing through the skin; and

means for removably securing the support layer in fluid communication with the subject's skin,

wherein each analyte detection reagent contained on each analyte detection zone comprises a specific binding partner for an analyte to be determined, and each reference detection reagent contained on each reference zone comprises a specific binding partner for a reference substituent in the perspiration.

25. A dermal concentration patch for determining the presence of an analyte in a subject mammal's perspiration, in which false negative results produced through the addition of adulterants to the patch can be detected, comprising:

a water permeable support layer having a first side and a second side, said first side being applicable to the subject's skin;

means for removably securing the first side of the support layer in fluid communication with the subject's skin; and

a test region on said patch for detecting the presence of an adulterant capable of producing false negative results in an assay for the analyte, said test region being on a strip disposed within a region of the patch hidden from the subject's view while the patch is worn by the subject, thereby providing the subject with no visible indication of the test region,

wherein water is permitted to escape through the support layer and outside of said concentration patch.

26. A dermal concentration patch for determining the presence of an analyte in a subject mammal's perspiration, comprising:

a water permeable support layer in which said analyte can be concentrated

means for removably securing the support layer in fluid communication with the subject's skin; and

a reagent which is a specific binding partner for a reference substituent in perspiration immobilized in the support layer, said reference substituent being selected from the group consisting of albumin and IgG,

wherein water is permitted to escape through the support layer and outside of the concentration patch, thereby allowing said analyte to be concentrated in said support layer.

27. A dermal concentration patch for determining the presence of an analyte in a subject mammal's perspiration, comprising:

a water permeable support layer in which said analyte can be concentrated

means for removably securing the support layer in fluid communication with the subject's skin; and

a reagent which is a specific binding partner for a reference substituent in perspiration immobilized in the support layer, said reagent being selected from the group consisting of an antibody and an antigen,

wherein water is permitted to escape through the support layer and outside of the concentration patch, thereby allowing said analyte to be concentrated in said support layer.

28. A dermal concentration patch for determining the presence of an analyte in a subject mammal's perspiration, comprising:

a water permeable support layer in which said analyte can be concentrated

means for removably securing the support layer in fluid communication with the subject's skin; and

a reagent which is a specific binding partner for a reference substituent in perspiration immobilized in the support layer; and

indicator chemistry within the patch for providing an indication of the binding of said reference substituent to said reagent,

wherein water is permitted to escape through the support layer and outside of the concentration patch, thereby allowing said analyte to be concentrated in said support layer.

29. The patch of claim 28, wherein said indication is a color change.

30. A method of determining the presence of a drug of abuse or metabolite thereof in a subject mammal's perspiration, comprising:

removably securing a water permeable support layer in fluid communication with the subject's skin, said support layer being in combination with a concentration patch;

accumulating perspiration from said subject in said support layer for a test period of time;

permitting water to escape through the support layer, thereby concentrating the drug of abuse or metabolite thereof in the support layer; and

detecting false test results if present by including a soluble marker within said patch and detecting the presence of the quantity of said marker after completion of the test period,

wherein a substantial loss in the quantity of soluble marker present in the patch is indicative of a false negative result.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

The present invention relates to diagnostic kits for determining the presence of one or more analytes in a fluid sample. More particularly, the present invention relates to a dermal concentration patch for increasing the concentration of an analyte expressed through the skin to a conveniently measurable level.

The determination of a patient's physiological status is frequently assisted by chemical analysis for the existence and/or concentration of predetermined chemical species in a body fluid. These tests, which are typically conducted in the physician's office or in the hospital, may be characterized by their collection technique as invasive, such as analyses of blood, or non-invasive, such as analyses of urine and perspiration.

Blood is frequently analyzed for a wide variety of components, and clinical laboratories are generally equipped with instrumentation which can provide a highly quantitative profile of the blood's composition. However, blood collection is inherently invasive, and therefore attended by several disadvantages. Analyses based upon ., collection of a sample of blood are generally restricted to the physician's office or clinical laboratory, which reduces convenience for ambulatory patients and greatly increases cost. In addition, some risks associated with an invasive procedure can range from undesirable at best to unacceptable, depending upon the condition of the patient, and the nature and necessity of the test desired to be performed.

Many analytes or metabolites of interest can additionally be detected in urine, which is characterized by its predictable supply and non-invasive collection. However, as will become apparent, urine analysis is not well suited for use in the principal intended application of the concentration patch of the present invention.

Perspiration is, under certain circumstances, an ideal body fluid for analysis in the determination of physiological status. Its non-invasive collection renders it suitable for use out of the physician's office, and its similarity to blood in terms of its content of biological molecules renders it suitable for a wide range of physiological testing.

Thus, a variety of diagnostic kits for monitoring an analyte in sweat have been developed. For example, U.S. Pat. No. 3,552,929 to Fie1ds, et al. discloses a bandaid-type test patch particularly suited for determining the chloride ion concentration in perspiration as a method of diagnosing cystic fibrosis. The apparatus disclosed in Fields comprises an absorptive sweat collecting pad with an impermeable overlying layer for the purpose of preventing evaporation. When the absorptive pad is saturated, the patch is removed from the skin and exposed to a series of strips impregnated with incremental quantities of silver chromate or silver nitrate, the color of which undergoes a well known change upon conversion to the chloride salt.

U.S. Pat. No. 4,706,676 to Peck discloses a dermal collection device which comprises a binder to prevent reverse migration of an analyte, a liquid transfer medium which permits transfer of an analyte from the dermal surface to the binder, and an occlusive cover across the top of the liquid transfer medium and binder.

Peck discloses application of the dermal collection patch in the detection of human exposure to various environmental chemicals. After the dermal collection device has been worn on a patient's skin for a period of time, the patch is removed for analysis. Analysis involves chemical separation of the bound substance of interest from the binding reservoir and thereafter undertaking qualitative and/or quantitative measurement by conventional laboratory techniques.

The prior art generally suffers from one or more important limitations when convenient field use of a diagnostic test patch is desired. In particular, prior art diagnostic test patches are generally only useful for determining the presence of analytes such as halide ions, which are present in sweat in relatively high concentrations. Other prior art dermal patches are merely collection devices from which the analytes must later be separated and concentrated or otherwise prepared for analysis in accordance with known laboratory techniques. In addition, the occlusive outer layer type devices of the prior art are susceptible to the problem of back diffusion of perspiration and/or analytes contained therein.

Thus, there remains a need in many diverse applications for a method and apparatus for the non-invasive determination of a preselected analyte in a body fluid such as perspiration, which can be utilized to detect the presence of low-concentration analytes in perspiration without the need for conventional instrumentation. Additionally, these remains a need for a method and apparatus for the non-invasive determination of a preselected analyte in insensible or non-exercise perspiration. The test kit should be low-cost and suitable for convenient use by non-medical personnel.

SUMMARY OF THE INVNETION

There is provided in accordance with one aspect of the present invention a dermal concentration patch for concentrating components of a body fluid under the influence of body heat, which comprises a concentration zone in communication with a source of body fluid and a discharge zone which is exposed to the atmosphere to permit escape of at least a portion of the substantial water component and other undesired components in the body fluid.

In one embodiment, a hydrophobic membrane is provided to separate the concentration zone from the discharge zone. By hydrophobic, it is meant in the context of the present invention that the membrane prevents the passage of fluid phase but permits the escape of vapor phase of volatile components. These hydrophobic membranes shall also be referred to herein as gas permeable membranes. When a gas permeable membrane is provided, the transition of body fluid accumulated in the concentration zone to the vapor phase is accelerated under the influence of body heat, thereby concentrating the non-volatile and less volatile components in the concentration zone.

Alternatively, the concentration zone and the discharge zone may be separated by a hydrophilic layer. By hydrophilic, it is meant in the context of the present invention that the membrane or layer permits the passage of both liquid and vapor phases. Such hydrophilic layers will also be referred to herein as liquid permeable membranes. Where liquid permeable membranes are provided, passage of the fluid phase into the discharge zone is permitted.

The concentration patch is preferably provided with an analyte determination zone having detection chemistry such as an immobilized specific binding partner for an analyte to be determined in the body fluid. An analyte reference zone may additionally be provided, which provides a means for determining whether a sufficient amount of body fluid has passed through the analyte determination zone to sufficiently determine the existence of the analyte. The analyte reference zone preferably produces a visible indicium upon exposure to a predetermined threshold, such as a predetermined volume of fluid, or a threshold amount of a reference analyte such as IgG, albumin or the like.

In accordance with a further aspect of the present invention, there is provided a method of detecting false negative results in an assay of a body fluid from a subject, which are the result of noncompliance with the testing procedure by the subject. The method comprises the steps of securing a test patch to the subject in communication with a source of body fluid, the test patch comprising a first detection chemistry for detecting the presence of an analyte in the body fluid, and a second detection chemistry for detecting the presence of a reference substituent in the body fluid.

The test patch is removed from the subject after a sufficient test period of time to enable the first detection chemistry to detect the analyte, if present in the body fluid. The amount of reference substituent detected by the second detection chemistry is then determined, and the amount of reference substituent determined is compared to a predetermined value to determine whether the test patch was actually worn for substantially all of the test period.

Further features and advantages of the present invention will become apparent from the Detailed Description of Preferred Embodiments which follows, taken together with the claims and appended figures hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a dermal concentration patch according to one embodiment of the present invention.

FIG. 1a is a cross-sectional view along the line 1a-1a of the dermal conoentration patch of FIG. 1.

FIG. 2 is a perspective view of a dermal concentration patch according to a second embodiment of the present invention.

FIG. 2a is a cross-sectional view along the line 2a-2a of the derma1 concentration patch of FIG. 2.

FIG. 3 is a perspective view of a third embodiment of the dermal concentration patch of the present invention.

FIG. 3a is a cross-sectional view along the line 3a-3a of the patch of FIG. 3.

FIG. 4 is a perspective view of one embodiment of a reagent packet for use in effecting a color change responsive to the presence of analyte in the concentration patch of the present invention.

FIG. 5 is an exploded elevational schematic view of a fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view of a dermal patch according to a further embodiment of the present invention.

FIG. 7 is a plan view of a dermal patch according to another embodiment of the present invention.

FIG. 8 is an exploded elevational view of a dermal concentration patch according to yet another embodiment of the present invention.

FIG. 9 is a plan view of a dermal concentration patch according to a further embodiment of the present invention.

FIG. 10 is an exploded elevational view according to still another embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, there is disclosed a dermal concentration patch 10 according to one embodiment of the present invention, illustrated as secured to the surface of the skin 12. As will be appreciated by one of skill in the art, the concentration patch of the present invention may be used for veterinary purposes as well as on humans. In addition, the concentration patch can be used in more diverse applications such as in agriculture or any other environment where a chemical species is to be detected in a fluid and a heat source such as body heat, sunlight, etc. is adaptable to effectuate the distillation or other concentration function of the patch. The preferred use, however, is for determination of preselected chemical species in sweat, and the ensuing discussion is principally directed to that end use.

Moisture expressed from the skin 12 within the perimeter of the test patch 10 first accumulates in a concentration zone 14 beneath the first side of a gas permeable filter 16. The concentration zone 14 preferably contains a fluid-permeable medium 20 which may be cotton gauze or other commonly available permeable material. For example, a layer of any of a variety of known fiber webs such as knitted fabrics, or nonwoven rayon or cellulose fibers may be used. Filtration Sciences #39 is a particularly preferred fluid-permeable medium for use as a concentration zone in the present invention.

Moisture accumulates in the interfiber spaces of the medium 20 and, under the influence of body heat which is readily conducted from the surface of the skin through the fluid phase, the water component of the perspiration will tend to volatilize.

As previously discussed, the concentration patch 10 is provided with a gas permeable filter 16. By "gas permeable," I intend to designate any material which will permit the passage of the vapor phase of fluids expressed from the skin, but substantially retain the fluid phase within concentration zone 14. Any of a variety of suitable commercially available microfiltration membrane filters may be used for this purpose, such as the Gore-Tex 0.45 micron Teflon filter manufactured by W. L. Gore & Associates, Inc. (Elkton, Maryland).

I use the term "liquid permeable" in this patent to mean a material which will permit the passage of sweat in the liquid phase. A liquid permeable filter will allow the passage of water in both the liquid and vapor phases. Thus, when the term "water" is used herein, I mean to refer to both the liquid and vapor phases of water, unless reference is specifically made to a particular phase.

Adjacent the second side of the gas permeable filter 16 is a discharge Zone 18. As previously discussed, gas permeable filter 16 retains the fluid phase but permits escape of the vapor phase of the fluid component in perspiration. Thus, the vapor component which primarily consists of vaporized water continuously escapes through the gas permeable filter 16 exiting the second side thereof into discharge zone 18, which is in communication with the atmosphere. In an alternative embodiment, not separately illustrated, the gas permeable filter 16 is replaced by a liquid permeable membrane which permits passage of the fluid phase. In this embodiment, fluid, or a combination of vapor and fluid, will be permitted to escape from the concentration patch. Any of a variety of liquid permeable filters are commercially available which can be used to form a liquid permeable filter used in this embodiment of the present invention. A preferred liquid permeable filter is constructed from James River Paper Drape.

Disposed adjacent the second side of filter 16 in the discharge zone 18 is a flexible permeable outer layer 22. This layer serves to protect the filter 16 against physical damages such as abrasion, and can also serve as a barrier for preventing chemical contamination of the filter material from the outside. Layer 22 may comprise any of a variety of commercially available vapor permeable tapes and films which are known to one of skill in the art. Layer 22 may be distinct from or integral with tape 26 discussed below. Alternatively, depending upon the intended application of the patch, layer 22 may be deleted altogether, where it does not appear that abrasion or external contamination will deleteriously affect the concentration patch 10.

The concentration patch 10 illustrated in FIG. 1 is secured to the surface of the skin by means of a peripheral band of tape 26. Preferably, tape 26 will extend around all sides of patch 10. For example, an annular ring of tape can be die punched for use with a circular patch, or the center of a rectangular piece of tape can be removed to expose layer 22 or filter 16 of a rectangular patch. See FIGS. 1 and 3, respectively. Alternatively, layer 22 and tape 26 could be deleted altogether and layers 16 and 20 could be secured to the surface of the skin by a bandage. One such method would be to capture layers 16 and 20 under a bandage or wrapping surrounding the arm or the leg. In this case, the vapor and/or fluid is permitted to escape through 16 and 20 and into the bandage where it may either collect there or dissipate into the environment.

A large variety of hypoallergenic or other suitable tapes are well known in the art, which may be adapted for use with the concentration patch 10 of the present invention. Different tapes or adhesives may be desirable depending upon the intended use of the test kit, based upon their ability to adhere to the skin during different conditions such as daytime wearing under clothing, during sleep, during profuse sweating for prolonged periods or during showers. It has been determined that the most desirable tapes include multiple perforations which prevent sweat from building up underneath the tape and eventually compromising the integrity of the adhesive. Preferably, a tape, such as Dermiclear marketed by Johnson & Johnson, will be used.

Any of a wide variety of means for securing the concentration patch 10 to the skin 12 may be utilized. For example, the tape 26 can be eliminated and gauze layer 20 provided with a lower adhesive layer to perform the same function. One such adhesive membrane is the MN-100 adhesive membrane manufactured by Memtec of Minnetonka, Minnesota. This membrane is liquid permeable so that it passes fluid as would the gauze layer 20, yet has one adhesive side so that it will stick to the skin. Alternatively, outer protective layer 22 can comprise an annular flange 23, extending radially outwardly beyond the outer edges of filter 16 and gauze 20. See FIG. 2a. The lower surface of the flange 23 is then provided with a suitable adhesive.

The surface temperature of human skin varies regionally, however, it is generally within the range of from about 86.degree. to about 90.degree. F. at rest, and can rise to much higher temperatures under conditions of strenuous exertion. At those temperatures, a number of chemical species of interest for the purpose of the present invention, such as creatine kinase, a high or low density lipoprotein have a sufficiently low vapor pressure that volatilization is not a significant factor in the efficiency of the concen