Drug Breakdown: Fentanyl

02 October 2023
Volume 5 · Issue 10


In this column, Sharon Rees aims to refresh knowledge and interest in some of the commonly used drugs in a series of tweets. This month she is talking about #fentanyl

Day 1: A synthetic opioid discovered circa 1960 (from phenylpiperidine) #fentanyl is x 50-100 more potent compared to morphine. Originally for anaesthetic i.v use; also now used for moderate-severe acute/chronic pain management via alternative formulations. Schedule 2 controlled drug

Day 2: #fentanyl uses include anaesthetic & peri-operative pain management, leading to drowsiness, happiness, sedation. Buccal lozenge & sub-lingual tablets/sprays & nasal spray for acute/breakthrough pain e.g palliative care, as well as transdermal patches for chronic pain. Dose depends on use

Day 3: #fentanyl i.v use leads to rapid onset sedation (high lipid solubility), analgesia, bradycardia, respiratory depression. Patch absorption bioavailability over 90%;3 or more days to reach steady state (chronic pain). Skin temp increase can increase absorption. High Vd, high liver metabolism (CYP3A4) > inactive metabolites/renal excretion. T½ varies between formulations in the range ~7-12hrs (prolonged for patch). Renal/hepatic impairment can increase exposure. In elderly there is lower clearance, so care re toxicity. Interestingly, increased clearance in obesity (i.v)

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