Opioids for severe pain quiz

Local redness or itching around injection site is due to direct histamine release and is not an IgE mediated anaphylactic or allergic reaction, so morphine can be given to the same patient again. It can be prevented by dilution and slower administration. (Link)

Fentanyl can be used in renal failure due to its extensive hepatic metabolism. It has less haemodynamic effects than morphine and has a slightly more rapid onset than morphine. Unlike morphine, it does not have an active metabolite that can accumulate and cause toxicity with repeated administration. (Link)

The correct initial dose is 1.5 µg/kg, repeated 5 minutely to effect.

Fentanyl is more likely to cause muscular rigidity and dystonia than morphine (although usually only at anaesthetic doses (15microg/kg). Morphine is longer acting, more likely to cause histamine release or bradycardia. (Link)

Carfentanyl is the most potent derivative – 30 times that of fentanyl. Sufentanyl is 15 X as potent, acetyl fentanyl is 5 X as potent and remifentanyl is only 2/3 the potency of fentanyl. (Link)

Pethidine can cause a neuroleptic malignant type reaction in patients taking SSRIs or MAOIs. It is more sedating than morphine and, due to its long acting metabolite norpethidine, is a potent cause of confusion in the elderly with repeated doses. Unlike morphine, it usually increases heart rate a little due to a direct chronotropic action.(Link)