What does the amount on a patch label mean?

Each word in the title describes its own measurement. “Loaded” is what goes into the patch. “Released” is what leaves its formulation. Beyond that, scientists use skin samples and studies in people, each designed around its own question.

Knowing which is which makes any label, and any study, easy to read.

1. Loaded: the starting amount

An ingredient load is the quantity built into a patch. It is the clearest composition fact a label can carry: what is in the patch, and how much.

On a 24/sync label, every amount is what goes into each patch, down to the milligram. Our evidence register records the source behind each figure.

2. Released: leaving the formulation

A release test follows material leaving a formulation under defined conditions. A laboratory can study release with great precision, and a good result states what was tested, for how long and by which method.

Researchers also measure what remains in a patch after wear. The FDA’s 2011 guidance on residual drug covers this for medicinal and related patch systems, and shows how closely patch design is studied at every stage of wear.

3. Skin studies: following an ingredient through a sample

Skin permeation studies ask how an ingredient moves through a skin sample. The OECD’s laboratory skin method holds a skin sample between two chambers and measures where the test substance is recovered over time.

It is a precise, well-controlled way to study a formulation. A good report names the skin, the formulation and the test setup, so every result is tied to its conditions.

4. In people: measuring exposure over time

For products intended to deliver an ingredient around the body, researchers can study blood concentrations over time. Good designs account for the body’s existing levels of that substance and take a series of readings across the wear time.

In medicine development, the FDA’s 2022 guidance describes how scientists measure the rate and extent to which an ingredient becomes available at its site of action, as one part of the wider evidence for a product. It is guidance for medicines, cited here as background science.

5. A meaningful benefit: the result that matters to you

Outcome studies ask the question closest to everyday life: what changes for the person using a product? They measure a defined outcome, with a relevant comparison, population and duration.

A laboratory result, a blood marker and an everyday outcome each answer their own question. Read each finding at the level it was measured. For your own routine, the simplest measure is yours: give it a couple of weeks of daily wear and notice how your days feel.

Use the distinction when comparing labels

• Check the unit. One milligram equals 1,000 micrograms. A small-looking number may use a different unit.
• Check the substance. The mass of a compound and the mass of one component within it are two different figures.
• Check the measurement. Is the number loaded, released, found in a laboratory receiver, or measured in people?
• Check the product match. Was the tested formulation the one you are considering?

Every amount on a 24/sync label is what goes into each patch. A patch is designed to release steadily across hours of wear, while a capsule is swallowed in one go, so compare the two as formats rather than milligram for milligram.

To see how these measurements fit together, continue with how ingredient patches work. To choose around your everyday preferences, see our format comparison.

Sources

• FDA, August 2011: Residual drug in delivery systems.
• OECD, 2004: Test No. 428, skin absorption in vitro.
• FDA, April 2022: Bioavailability studies, general considerations.