Fentanyl Patch

Products

Transdermal fentanyl has been approved in many countries since 1996 (Durogesic, generic). Various strengths are available. The larger the patch, the more fentanyl is released per unit time: 12 µg/h, 25 µg/h, 50 µg/h, 75 µg/h, and 100 µg/h. The opioid is legally classified as a narcotic.

Structure and properties

Fentanyl (C₂₂H₂₈N₂O, M_r = 336.5 g/mol) exists as a white powder that is practically insoluble in water. It is an analog of pethidine and a piperidine derivative. Fentanyl can be administered through the skin because it is potent at low doses, lipophilic, and a small molecule. This also facilitates its passage across the blood–brain barrier into the central nervous system.

Effects

Fentanyl (ATC N02AB03) has potent analgesic, sedative, and psychotropic properties. The effects are due to agonism at µ-opioid receptors in the central nervous system. The analgesic potency is 75 to 100 times greater than that of morphine. Therefore, it can be administered in small doses.

Indications

For the treatment of severe and persistent pain, as a second-line agent.

Dosage

According to the SmPC. The patch can be worn continuously for 72 hours (3 days) on a skin site of the upper body or upper arms. The new patch must be applied to a new site. Directions for use: See also under Administering TTS.

Abuse

Like other opioids, fentanyl can be abused as a depressant and euphoric intoxicant and can become addictive.

Contraindications

For complete precautions, see the drug label.

Interactions

• Fentanyl is a substrate of CYP3A4 and corresponding drug-drug interactions are possible.
• Central depressant drugs and alcohol may potentiate adverse effects.
• Combination with MAO inhibitors is not indicated because serious adverse effects are possible.
• Opioid antagonists abolish the effects of fentanyl.
• Serotonergic agents increase the risk of serotonin syndrome.
• Anticholinergic agents increase the risk for constipation and urinary retention.

Adverse effects

The most common possible adverse effects include nausea, vomiting, constipation, drowsiness, dizziness, and headache. In the event of an overdose, life-threatening respiratory depression may occur. Therefore, the precautions and detailed information in the drug label must be followed carefully.