FAQ

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Technology & History
No. The ability to identify drugs in sweat has been known since the early 1970’s. The PharmChek® Sweat Patch is a breathable device that facilitates the collection of sweat when applied to the donors skin. It has been used in criminal justice for over three decades.
No. The testing procedures used for the analysis of sweat are the same well-established procedures used for the analysis of urine, oral fluid and hair samples. Samples are tested using LC-MS/MS (Liquid Chromatography-Tandem Mass Spectrometry) to definitively identify the drugs in the sample.
The PharmChek® Sweat Patch is intended to provide specimens for laboratory analysis of drugs of abuse. It is not used for a medical purpose and does not meet the requirements of the medical Device Regulations for a medical device. Therefore, the PharmChek® Sweat Patch does not require a CE mark.
Yes, the detection of drugs in sweat has been studied for a number of years yielding a large number of peer review publications. There are over 50 papers published on detection of drugs from the PharmChek® Sweat Patch.
The review published by Giovanni and Fucci in 2013 (Curr. Med. Chem. 20 545-561) provides an overview of the sweat testing literature including the PharmChek® Sweat Patch. The authors conclude that sweat testing was found to be an effective mechanism to qualitatively monitor illicit drug use.
Yes, the PharmChek® Sweat Patch has been used in criminal justice in the United States for over three decades and it is now being adopted in Australia and New Zealand.
Wear Times & Application
The PharmChek® sweat Patch can detect use 24-48 hours before the application of the patch, during the wear period, or both. For example: a patch worn for 7 days might be positive because of drug use on Day 1 or on Day 6 or use in the 24 – 48 hours prior to the application of the patch.
Patches worn for at least 24 hours following drug use can identify the drug used.
The typical wear period is up to 10 days although this may vary from person-to-person based on factors including skin type and level of activity.
The preferred location is the upper outer arm, but it can also be placed on the lower back or midriff. The area of application should not have excessive hair or be rubbed by tight clothing.
The PharmChek® Sweat patch is manufactured from Tegaderm. Tegaderm is a hypoallergenic material used as a wound dressing to cover catheter and IV sites of individuals in hospitals and widely used within the medical field. Allergic reactions are extremely rare.
The shelf life of the Sweat Patch is 2 years from the date of manufacture. Each collection kit is supplied with the expiry date clearly marked.
Once the laboratory receives the specimen, results are reported within 72 hours working hours.
Adulteration & Tampering
No, the PharmChek® Sweat Patch is a tamper-evident device. Each patch is imprinted with a unique identifying number, referred to as the URN, which is recorded on the Chain of Custody Form. This number is verified again by the trained Collector at the point of patch removal.
The PharmChek® Sweat Patch is a tamper-evident device. The adhesive material used on the sweat patch penetrates the upper epithelial layer of the skin. When the sweat patch is removed, these epithelial skin cells adhere to the adhesive, which means that the re-application of the patch is difficult as it no longer adheres to the skin. During natural wear, the film immediately surrounding the absorbent pad is well-adhered to the skin and intact, this is not the case if someone tries to remove and re-apply the patch. The adhesion of the patch will be closely examined by the trained Collector at the point of patch removal to confirm that the patch has not been compromised.
Patches are applied and removed by trained Collectors. Attempts to adulterate the absorbent pad, for example by introducing common chemicals, such as bleach, are obvious to a trained collector. They typically result in a visible discoloration of the white absorbent pad and/or discoloration or deformation of the polyurethane covering.
All information relating to the removal of the patch is recorded on the Chain of Custody Form by a trained Collector. Collectors can also take a photo of the patch at application and removal in order to evidence any observations recorded on the Chain of Custody Form.
No, drinking large amounts of fluid will not decrease the level of drug present in sweat.
No, if the correct procedures by a trained Collector during the application and removal of the patch. The absorbent pad within the patch is protected from the environment by a layer of polyurethane film. The film is a semi-permeable membrane which allows the transfer of water vapor and gases while preventing outside contaminants from entering the patch.
Sweat Patch Results
A Certificate of Analysis which details the testing performed and the results obtained is provided. Results are accessed via a results portal.
The certificate will contain the cut-off use during testing in ng/patch. Any results below the cut-off will be reported as negative, results above the cut-off will be reported as positive.
The cut-offs have been selected based on peer reviewed literature which details the level of drug present in sweat in individuals who have used drugs and the cut-offs currently being applied in the criminal justice setting. They are designed to ensure that drug use over the wear time of the patch, and the 24 – 48 hours prior to patch application will be detected.
No. The PharmChek® Sweat Patch collects sweat over the period it is worn. Therefore, a positive result indicates drug use within the period of 24 hours before the application up until the time the patch is removed. It is not possible to distinguish between multiple episodes of drug use.
It is not possible to determine exactly when the drug use took place, only that the drug use took place approximately 24-48 hours before the application of the patch, during the wearing of the patch, or both.
It is possible to detect residual usage between multiple patch wear periods if drugs were consumed late in the first wear period and therefore detected early in the second patch wear period.
A THC positive on the patch indicates recent use. Daily use is unlikely to result in the detection of residual use between patch wear periods beyond the first patch wear (7-10 days).
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