Drug Breakdown / CPD

Drug Breakdown: Fentanyl

02 October 2023
Prescribing
02 October 2023
Volume 5 · Issue 10

Abstract

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

Dr Sharon Rees @reesprescribe

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

Dr Sharon Rees @reesprescribe

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

Dr Sharon Rees @reesprescribe

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)

Dr Sharon Rees @reesprescribe

Day 4: Opiate action; agonism of the mu opioid receptor suppresses neurotransmission. Powerful effect on brain reward circuit leading to rapid dependence & addiction. High research focus on receptor binding properties compared to morphine, with implications for abuse & also reversal in overdose

Dr Sharon Rees @reesprescribe

Day 5: #fentanyl DDIs. Multiple as per all opioids; severe DDIs with enzyme inhibitors e.g macrolides & some anti-virals e.g lopinavir, as can increase exposure. Use with clozapine can lead to intestinal obstruction. Buprenorphine can increase opiate withdrawal (NOT exhaustive)

Dr Sharon Rees @reesprescribe

Day 6: ADEs multiple as per opioids e.g N&V, arrhythmias, dry mouth, substance abuse disorder. #fentanyl may have a better SE profile c.f morphine e.g patch causing less nausea. If opioid naïve then increased risk of respiratory depression from patches;recommended to try other opioids 1st. Naloxone can block #fentanyl in overdose, but a rapid response is needed & multiple doses may be necessary to reverse. (NOT exhaustive)

Dr Sharon Rees @reesprescribe

Day 7: #fentanyl abuse has meant increased trafficking/overdose deaths globally from respiratory depression. Issue as ‘hidden’ ingredient when used as cheap ‘mixer’ with other opioids eg heroin. Gel from patches can be abused via chewing/injecting contents, or heated & inhaling smoke

EARN YOUR CPD CERTIFICATE

With the help of Prescribing and Therapeutics Training Ltd and the Journal of Prescribing Practice, you can earn your 1-hour CPD certificate

In addition to the tweets, read the BNF treatment summaries on analgesics, chronic pain and peri-operative analgesia, as well as the monograph on fentanyl and SPCs for various formulations as resources (one example only below). Once you have completed this, answer the 10 questions. Submit your answers to reesprescribe@gmail.com. If you answer at least eight out of 10 questions correctly, you will receive your CPD certificate via email.

Further reading on #fentanyl

  • https://bnf.nice.org.uk/drugs/fentanyl/
  • https://bnf.nice.org.uk/treatment-summaries/analgesics/
  • https://bnf.nice.org.uk/treatment-summaries/analgesics/#opioid-analgesics-and-dependence
  • https://bnf.nice.org.uk/treatment-summaries/peri-operative-analgesia/
  • https://www.medicines.org.uk/emc/product/10272/smpc#gref
  • Fentanyl is a strong opioid compared to morphine TRUE or FALSE?
  • Fentanyl is used for all levels of pain TRUE or FALSE?
  • Transdermal application is the only route used in palliative care TRUE or FALSE?
  • Which of the following is TRUE?
  • Fentanyl has a rapid onset of action through all routes of administration
  • Fentanyl is highly lipid soluble
  • All routes of administration have high bioavailability
  • The processes of metabolism produce active metabolites
  • Reduced clearance of fentanyl in the elderly can mean an enhanced effect TRUE or FALSE?
  • A low affinity of fentanyl to the mu opioid receptor means strong action but for a short duration TRUE or FALSE?
  • Which of the following is FALSE?
  • If chronic use, abrupt withdrawal should be avoided
  • If someone using a patch has a fever, absorption of fentanyl could be increased
  • Naloxone needs to be given rapidly for fentanyl in the event of an overdose
  • Respiratory depression is less severe for fentanyl compared to morphine
  • Enzyme inhibitors, such as clarithromycin, can mean increased clearance and loss of therapeutic effects TRUE or FALSE?
  • Fentanyl is a drug related to growing abuse across the world TRUE or FALSE?
  • Which of the following is a common adverse drug effect for transdermal fentanyl?
  • Diarrhoea
  • Constipation
  • Memory loss
  • Apnoea