Fentanyl vs. other opiates concerning hepatic function

[StaffWriter]

My friend is in the hospital trying to fight off an infection in his leg. He's got what they believe to be Chronic Lymphocytic Leukemia/Lymphoma. He's going thru chemo to see if the tumors in his liver and lung will shrink due to the chemo. If not, then they are secondary cancers from his damaged liver (cirrhosis). Anyway, we are trying to get his pain under control and me and the doctor sat and talked a while about his situation. I said fentanyl would be a good idea since it is time released and it lasts around 72 hours. She said no because she said Fentanyl can build up in the liver and can't get metabolized fast enough. All other opiates seem to be fine with her. So why would his Oncologist doctor write him for a script of fentanyl, but this hospital doctor won't? What would, if true, make fent accumulate in the liver? Thanks guys!

Ted Cruz 2016

 

[sekio]

fentanyl is primarily metabolized by CYP3A4, an enzyme in the liver.

there is also cyp3a4 present in the intestine. if he's in the hospital being monitored then fentnayl is totally appropriate, it just needs to be dose-adjusted to deal with the fact that it will have a longer than normal half life. that is your friend may not need as much fentanyl as the average person. that shouldn't actually be a problem because in normal individuals fentanyl has a very rapid metabolism. so even if your liver was functioning at a low level you would still expect the gut enzymes to work to break it down.

the fentanyl patches release fentanyl into the subcutenateous fat where it acts like a depot time release (72h+ half life). fentanyl itself when it's injected IV (for instance induction of anaesthesia) the one thing to consider with the patches is that if he experiences large amounts of body fat loss while on the patches then he could be at risk of od as blood levels of fentanyl will rise.

if he is on high doses of "strong" opioids already e.g. hydromorphone, morphine, oxycodone and he has pre-existing tolerance developed then he will be even less likely to od.

 

[endotropic]

Maybe the hospital doctor knows about some specific interaction (possibly metabolic) between fentanyl and one of the other medications your friend takes? For something with such a small margin of error as fentanyl you want to avoid any possible unpredictability.