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1
Institut de Médecine Légale, 11 rue Humann, 67000 Strasbourg, France.
2
Institute of Pharmacy, Baltzerstr. 5, 3012 Bern,
Switzerland.
a Author for correspondence. Fax 33.3.88.24.00.85.
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResults and DiscussionReferences |
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Key Words: indexing terms: gas chromatography–mass spectrometry • drugs of abuse • morphine
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResults and DiscussionReferences |
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The sweat patch acts as a specimen container for nonvolatile and liquid components of sweat, including drugs of abuse. A unique number imprinted on each patch aids with chain of custody and identification. Sweat components are collected on a special absorbent pad, located in the center of the patch. Nonvolatile substances from the environment cannot penetrate the transparent film—a semipermeable membrane over the pad that allows oxygen, water, and carbon dioxide to pass through the patch and leaves the skin beneath healthy. Worn over a period of several days, the pad becomes saturated with sweat and slowly concentrates it; drugs present in the sweat are retained. The collection pad has a surface of ~14 cm2 and collects at least 300 µL per day of insensible perspiration in a 22 °C environment. Exercise, higher temperatures, or other factors that increase sweating increase the amount of sweat collected.
To date, few applications of the sweat patch have been published; these applications include tests for cocaine (8)(9)(10)(11), opiates (9)(11)(12), benzodiazepines, (11)(13), barbiturates (12), cannabis, buprenorphine, and methylenedioxyethylamphetamine (11). In these studies, the various authors concluded that sweat testing offered a relatively noninvasive method for obtaining a cumulative estimate of drug exposure over several days.
In two papers (9)(11), heroin exposure was documented in sweat by targeting the parent drug, or 6-acetylmorphine, or both. The aim of the present study was to evaluate excretion of heroin and its metabolites in sweat after the intravenous administration of controlled heroin.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResults and DiscussionReferences |
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chemicals
Acetonitrile was of HPLC grade (Merck, Darmstadt, Germany).
All drugs and deuterated internal standards (heroin-d9,
6-acetylmorphine-d3, and morphine-d3) were
purchased from Radian (Austin, TX).
N,O-Bis(trimethylsilyl)trifluoroacetamide (BSTFA)
plus 10 mL/L trimethylchlorosilane (TMCS) was purchased from Interchim
(Montluçon, France).
analysis of sweat patches
The target drugs were extracted from the absorbent pad in 5 mL of
acetonitrile in the presence of 100 ng of the following deuterated
internal standards: heroin-d9,
6-acetylmorphine-d3, and morphine-d3. The
samples were shaken for 30 min on an orbital shaker at 200 rpm. Then
the acetonitrile solution was divided into two portions: 2 mL for
heroin testing and the remainder for the other compounds
(6-acetylmorphine and morphine).
The acetonitrile was evaporated to dryness in both vials. Heroin was
not derivatizated, and the residue from the first portion was
reconstituted with 25 µL of acetonitrile. The other drugs (in the
second portion) were derivatizated by silylation for 20 min at 60 °C
with 40 µL of BSTFA containing 10 mL/L TMCS. A 1.5-µL portion of
each extract was injected through a HP5-MS capillary column [5%
phenyl–95% methyl siloxane, 30 m x 0.25 mm (i.d.)] into a
Model 5890 gas chromatograph coupled with an HP 5989 B engine mass
selective detector (all from Hewlett-Packard, Les Ulis, France).
Injector temperature was 260 °C, and splitless injection was used
with a split-valve off-time of 0.75 min. The flow of helium through the
column was 1 mL/min. Column temperature was programed to rise from an
initial temperature of 60 °C (held 1 min), to 290 °C at
30 °C/min, and held at 290 °C for the final 6 min. The ions
monitored and typical retention times of the various analytes and the
deuterated internal standards are presented in Table 1
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Results and Discussion |
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TopAbstractIntroductionMaterials and MethodsResults and DiscussionReferences |
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).The extraction recoveries were 71.3%, 76.4%, and 70.9% for morphine,
6-acetylmorphine, and heroin, respectively. These recoveries were lower
(11) than those observed after methanol extraction (~90%
for all of the drugs). However, when methanol was used, ~10–20% of
the heroin was converted to 6-acetylmorphine. Typically, when using
acetonitrile, hydrolysis of heroin was 5%, whereas 6-acetylmorphine
was stable under these conditions, giving no evidence of hydrolysis to
morphine. Moreover, to ensure stability of heroin, which in contrast of
6-acetylmorphine and morphine does not require derivatization, we
divided the extract into two portions for GC/MS assay. This split
procedure was reported to be suitable for heroin testing in blood,
urine, and saliva (14). Under the chromatographic conditions
used, there was no interference with the target compounds or the
deuterated standards by any extractable endogenous materials present in
sweat.
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Within-run and between-run CVs, studied after addition of 20 and 50 ng of pure substances to drug-free absorbent pads, were 13% for all drugs tested. The limits of detection were ~1.0, 1.0, and 0.5 ng/patch for morphine, 6-acetylmorphine, and heroin, respectively, at a signal-to-noise ratio >3.
Once stored at -20 °C, drug-free pads (n = 4) supplemented with 100 ng of each drug were stable for at least 1 month. Typically, hydrolysis of heroin and 6-acetylmorphine was <4% over that period.
Subjects wore the patch with minimal discomfort for 24 h, and each subject could continue his or her normal hygiene practices; nobody accidentally abraded the patch. No special precautions were observed during patch wear except to avoid rubbing with a towel after bathing. Tampering with the patch would be quite evident because once a patch has been applied to the skin, no more adhesive remains, so that one cannot remove and then reapply the patch.
Results of the sweat patch analysis are presented in Table 3
,along with the administered heroin doses. The ability of the patch to
collect and contain heroin and metabolites from sweat was demonstrated.
All the patches contained heroin, and except for one patch, the major
analyte excreted in sweat was heroin. Concentrations ranged from 2.1 to
96.3 ng/patch for heroin, from not detected to 24.6 for
6-acetylmorphine and from not detected to 11.2 for morphine. Heroin was
present at concentrations ~2–4 times higher than 6-acetylmorphine
concentrations and ~5–20 times higher than morphine.
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As with other drugs, the parent compound appears to be the major analyte in sweat after injection. Therefore, care is necessary to prevent the conversion of heroin or 6-acetylmorphine to morphine. No morphine 3-glucuronide or morphine 6-glucuronide was detected in the sweat patch, as analyzed by liquid chromatography with fluorometric detection (limits of detection for both compounds were ~1.0 ng/patch). Heroin was also identified in sweat collected from street addicts, as mentioned by Cone et al. (9) and Kintz et al. (11). In those studies, however, heroin was seldom the major analyte identified, probably because of hydrolysis in patches worn for several days.
The unique finding of heroin in sweat is of particular interest for documenting drug exposure of the subject. Administration of heroin to these subjects was done under close medical supervision, but no correlation could be established between daily doses and heroin concentrations (r = 2.59 x 10-5) or between daily doses and total opiates concentrations (r = 3.48 x 10-3). Substantial intersubject variability was associated with the excretion of heroin and its metabolites in sweat. Therefore, sweat testing seems to be a qualitative rather than a quantitative test to estimate the amount of drug administered. Similar observations were described for testing buprenorphine (11); for cocaine (9) or diazepam (13), however, the concentrations in sweat increased in apparent relation to the administered dose.
Patches can be worn continuously and used to monitor drug use during that period. However, sweat patches are not suitable for rapid screening purposes; there, urine, which is immediately available, appears to be the specimen of choice. Nonetheless, sweat testing offers the advantage of being a noninvasive method for obtaining a cumulative estimate of drug exposure, whereas urine presents an incremental measure with high invasiveness. The patch, easily applied and removed, is also easily stored (15).
In conclusion, sweat analysis may be an useful adjunct to conventional drug testing. Sweat specimens can be obtained more easily and with less embarrassment to subjects than urine specimens. This new technology may find useful applications in the treatment and monitoring of drug abusers.
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References |
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TopAbstractIntroductionMaterials and MethodsResults and DiscussionReferences |
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The following articles in journals at HighWire Press have cited this article:
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  E. W. Schwilke, A. J. Barnes, S. L. Kacinko, E. J. Cone, E. T. Moolchan, and M. A. Huestis Opioid Disposition in Human Sweat after Controlled Oral Codeine Administration Clin. Chem., August 1, 2006; 52(8): 1539 - 1545. [Abstract] [Full Text] [PDF]
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T. Saito, A. Wtsadik, K. B. Scheidweiler, N. Fortner, S. Takeichi, and M. A. Huestis Validated Gas Chromatographic-Negative Ion Chemical Ionization Mass Spectrometric Method for {Delta}9-Tetrahydrocannabinol in Sweat Patches Clin. Chem., November 1, 2004; 50(11): 2083 - 2090. [Abstract] [Full Text] [PDF]
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