> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/snomed-ct-specifications/snomed-ct-editorial-guide/readme/authoring/domain-specific-modeling/pharmaceutical-and-biologic-product/medicinal-product/index/index/prolonged-release-transdermal-patch.md).

# Prolonged-release transdermal patch

Prolonged-release transdermal patch clinical drug concepts modeled previously using concentration strength normalized to per 1 hour will use presentation strength based on the labeled total amount delivered over time (e.g., /16, /24 \[usual manufacturer-documented period], /72 hours), in alignment with product SPCs and international editorial policy.

Opioid patches (e.g., fentanyl, buprenorphine) are an exception and must retain the /1 hour expression, consistent with manufacturer documentation and regulatory standards. This reflects patient safety requirements for these strong, controlled substances. These concepts must also be modeled using presentation strength.

* Presentation strength is to be used for all prolonged-release transdermal patch concepts.
* The |Has unit of presentation (attribute)| with a value of |Patch (unit of presentation)| is added to all prolonged-release transdermal patch concepts.

Units will reflect the duration, strength, and units as specified in the SPC.

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