The Comprehensive Guide to Sweat Patches: How the Patch Works and How to Use It

The PharmChek® Drugs of Abuse Sweat Patch has been a reliable testing method in the criminal justice system for decades and now in the workplace. PharmChek® provides an unparalleled level of accuracy for drug testing. But what makes it a superior option to conventional sample collection and testing methods? It’s more than just what it tests; it’s the process we use.

What Are Sweat Patches?

The PharmChek® Drugs of Abuse Sweat Patch is an adhesive patch that absorbs sweat to test for the presence of drugs in the wearer’s system. The Sweat Patch is designed for long-term sample collection, and its tamper-evident construction has made it a reliable testing option for courts, parole officers, and other agencies. And as mentioned, this reliable drug detection device is now available in the workplace.

How the Sweat Patch Works

When an individual uses drugs of abuse, the parent drug metabolizes in the body and then travels throughout the body. It also arrives in the sweat, which is then excreted through the skin. For years, it’s been a known fact that drugs can be detected in sweat, but PharmChek® is the first consistent, convenient way to collect the sweat for analysis.

The PharmChek® Sweat Patch is applied to the skin and uses an absorbent pad to collect sweat over the course of its wear period. Its semi-permeable membrane allows lighter molecules like oxygen and water to escape while trapping heavier molecules, including the identifying compounds for drug use. The sample is then tested in an independent laboratory using a two-step verification process.

PharmChek® Sweat Patches are designed to be worn for at least 24 hours to collect an adequate testing sample, but the standard patch can be worn for up to 7–10 days. The optional PharmChek® Overlay can extend wear time to up to 14 days. Wearers can shower, exercise, and participate in normal activities throughout the patch’s wear time without fear of compromising the device or sample.

What Do Sweat Patches Detect?

The standard panel for the Sweat Patch detects several different drugs of abuse. There is also an expanded panel that detects the most common synthetic opiates. Unlike many other drug testing methods, PharmChek® can capture both the parent drug and its metabolites. PharmChek® does not deliver chemicals or medications to its wearer but instead simply collects chemicals through the body’s natural sweat-release process.

An optional fentanyl add-on is available for the standard panel if the full expanded panel is not required. The continuous sampling occurs throughout the wear time of the sweat patch, and any attempt to tamper with or remove the patch is easily detectable.

How the Sweat Patch Is Made

The PharmChek® Sweat Patch consists of an outside layer and an absorbent pad. The transparent polyurethane film covers the pad, sealing it on the skin with a hypoallergenic adhesive. The surgical-grade adhesive and film, both manufactured by 3M, keep the absorption pad free of any outside contaminants and damage. This material is still semi-permeable, allowing water vapor and air to pass through the film without allowing outside bacteria, water, or chemicals to enter.

The absorption pad collects the sweat for lab testing. This pad sits directly on the skin of the wearer. Between the pad and the outer film is the release liner, which allows the pad to be easily removed after the patch is worn. The only portion of the pad that is tested is the absorption pad. The rest of the Sweat Patch is discarded after being worn.

Each PharmChek® Sweat Patch has a unique ID number printed on the underside of the transparent film. This ID number ensures that the patch is the same when the wearer returns for collection. On the form, there is also a chain of custody number that matches the barcode printed on the security seal for each Sweat Patch so that there is no error in the collection, transport, or testing process.

How to Use Sweat Patches

The stringent standards and protocols required through PharmChek® are designed to prevent contamination, clearly identify any adulteration or damage, and provide secure transport from the point of collection to the final testing at Clinical Reference Laboratory in Lenexa, Kansas, near Kansas City, Missouri, the only lab PharmChem uses to test the PharmChek® Drugs of Abuse Sweat Patch. But even with these standards, the required protocols are easy to perform with the proper training. And PharmChek® provides a full certification course for trained observers to guarantee the efficacy of the application, removal, and testing process.

How to Apply PharmChek® Correctly

Each Sweat Patch kit comes with the materials you need to apply PharmChek® sweat patches correctly. Here is what you receive for each patch application:

• PharmChek® Drugs of Abuse Sweat Patch (50ct. or 10ct.)
• Single-use tweezers
• Specimen bags
• Transport bags
• 70% Isopropyl alcohol wipes
• Chain of custody form

You will also need disposable gloves for application, which are not included in the pack.

When starting the application process, the trained observer (who handles all aspects of the drug test process from application to mailing the sample) will go through specific steps to ensure a secure chain of custody, proper placement and application, and compliance with all specific demands of the process.

Before applying the Sweat Patch, the trained observer records information, including identifying ID numbers, the patch’s serial number, and the date. Then the observer also identifies the type of panel requested and why the test is being performed. The wearer and the observer must verify this information and sign the chain of custody form.

When applying the Sweat Patch, the trained observer thoroughly and aggressively cleanses the application area to remove any dirt and dead skin cells. This ensures a strong seal so that it can be worn for the full timespan. When the skin has dried, the observer applies the PharmChek® sweat patch.

The Sweat Patch is typically placed on the upper outer arm, but it can also be placed on the lower back or lower midriff. The location should not have obvious sores, cuts, scars, ulcerations, or skin irritations such as acne. While light tattoos without any obvious scar tissue are acceptable, the application should not have excessive hair.

How to Remove Sweat Patches Correctly

After the designated wear time, the trained observer contacts the wearer for the removal of the patch. Again, each kit comes with materials for proper removal, including:

• Specimen bag
• Single-use tweezers
• Donor’s chain of custody form (completed at application)
• Transport bag
• Laboratory mailing envelope

The observer examines the Sweat Patch for any evidence of tampering. The polyurethane film should be smooth and transparent, and it should be sealed around the pad. The edges can be curled without concern, so long as the pad is still sealed. In addition, any alterations to the patch itself should be noted.

To remove the Sweat Patch, the wearer first peels back the outer film from the corner until the absorption pad is exposed. The observer then grips the pad with the single-use tweezers and then removes the remainder of the outer film. The observer then places the absorption pad in the specimen bag and closes it with the security seal, which has a barcode and serial number printed on it.

The outer film is then inspected for damage or tampering, looking for any cuts, breaks, or punctures. Again, any damage is noted on the form. To ensure the security of the specimen, the observer writes the date and then initials the barcode seal for the specimen bag. The specimen bag, along with ply 2 of the chain of custody form, is then placed in the transport bag.

How to Ship Sweat Patches

With the pad properly sealed in the specimen bag and then in the transport bag, the sweat patch is ready to ship to the laboratory. More than one specimen can be sent in a single shipping envelope, making it simpler to ship a full set of tests at one time.

Storage of Sweat Patches

The Sweat Patch requires room temperature storage. Excessive heat and humidity can deteriorate the adhesive, preventing the Sweat Patches from sealing properly on the wearer’s skin. Excessive cold can also damage the Sweat Patch.

After sample collection, the absorption pads can be stored in a dry, room-temperature place for up to one month without adverse effects.

Testing Sweat Patches

PharmChek® uses a single independent laboratory for all testing, which guarantees a consistent and appropriate process every time a PharmChek® Sweat Patch is tested. The sample goes through an initial screening test to determine the presence of key compounds. If the sample tests positive for any specific parent drug or metabolite, the results are confirmed through Liquid Chromatography-Tandem Mass Spectrometry (LC/MS/MS) and a quality assurance review process before they are reported.

For methamphetamine and cocaine, the sample must have both the parent drug and metabolite present. This is a double confirmation that makes the test results incredibly reliable, and it’s unique to the PharmChek® testing method. The test results are reviewed by a laboratory extractionist, who analyzes every sample result and data point before sending them to the certification process.

Once approved for certification, the certifying scientist reviews the results again before the review of the final test result is performed. If any discrepancy is seen, the sample will be retested to confirm the test results completely.

The final results are reported online through a secure portal in as little as two days. The requesting party has a secured login to access the results.

Training and Certification for the Sweat Patch

The construction and testing protocols for PharmChek® set it apart from other drug testing methods, and the advantages the Sweat Patch offers start with our weekly training sessions and certification program. We encourage you to learn more about either option or contact our team to get started with PharmChek® today.