Overview
Duragesic was a prescription drug approved by the Food and Drug Administration (FDA) to treat pain in opioid‑tolerant patients in cases where pain was severe enough to require daily, long‑term, continual relief and other treatments were not effective. Duragesic was also referred to by its drug name, fentanyl. 

Duragesic was an opioid (a synthetic opiate) that worked as a potent analgesic (pain‑killer). It was believed to work by reducing the perception of pain.

How was it taken?
Duragesic was applied as a transdermal patch once every 72 hours. 

Side effects
The FDA‑approved label for Duragesic listed common side effects including headache, drowsiness, dizziness, fatigue, insomnia, sweating, nausea, diarrhea, vomiting, constipation and loss of appetite. 

Rare but serious side effects included overdose, dependency, and respiratory depression.

For more details about this treatment, visit:
Duragesic Skin Patch — Drugs.com