Transdermalpflasters

Transdermalpflasters, known in English as transdermal patches, are adhesive medical devices applied to the skin to deliver a drug into the systemic circulation over an extended period. They consist of an adhesive layer containing the drug, sometimes a rate-controlling membrane or matrix, and a protective backing. The drug diffuses through the skin, usually via the outermost layer (the stratum corneum), and enters the bloodstream, providing relatively steady plasma concentrations and avoiding first-pass metabolism in the liver.

Patches are designed as different delivery systems, including drug-in-adhesive patches where the medication is mixed with the adhesive, reservoir patches where a drug-containing reservoir is separated by a rate-controlling membrane, and matrix patches where the drug is dispersed in a polymer matrix. The rate of delivery depends on the formulation, the patch design, and skin properties.

Common uses and examples include nicotine patches for smoking cessation, fentanyl patches for chronic pain, estradiol or testosterone patches for hormone therapy, and scopolamine patches for motion sickness. Lidocaine patches are used for localized pain relief. Because patches can provide systemic exposure, they are often preferred when a steady dose is desirable or when oral administration is unsuitable.

Advantages of transdermal patches include controlled, sustained drug delivery, avoidance of gastrointestinal absorption issues, and improved adherence for some patients. Limitations include skin irritation or dermatitis at the application site, variable absorption due to skin condition or site, and potential overdose risk if exposed to heat or used concurrently with other sources of the same drug.

Usage guidelines emphasize applying to clean, dry, non-irritated skin; rotating sites; pressing the patch firmly for application; removing after the prescribed duration; and disposing of used patches safely to prevent accidental exposure.