Transdermal fentanyl overdose: don’t let the pharmacokinetics fool you

[23536]

This case report is annoyingly brief and doesn’t make any new points, but does highlight an important take-home lesson. The case is of a 15-year-old girl found apneic at home after having applied five of her stepfather’s fentanyl patches (100 μg/h each) to her body in a suicide attempt. She required multiple doses of intramuscular and intravenous naloxone to maintain respiratory drive and level of consciousness, and then a naloxone drip for 36 hours after presentation.

Here’s the tricky part: because fentanyl is so short-acting (duration of IV dose 0.5 – 1.0 hours), it is easy to underestimate how long the effects of transdermal fentanyl will last. However, because of the concentration gradient, when a fentanyl patch is applied a depot of the drug is taken up by skin layers and slowly released into the system. Therefore, even after the patches are removed serum levels can increase, since the elimination half-life is 13 – 22 hours. Patients who experience respiratory depression from fentanyl patches should be observed in a monitored setting for at least 24 hours after patch removal.

http://www.thepoisonreview.com/2012...rdose-dont-let-the-pharmacokinetics-fool-you/

 

[23536]

I did not know that. It's definitely counter-intuitive that for a short-acting opioid you'd need dose after dose after dose of naloxone. I bet many doctors would be surprised by this too.

I imagine that would suck for a fent addict that accidentally ODs, and then has to be thrust into precipitated withdrawal again and again and again in the ER.

 

[Cloudy]

I dunno, we covered this fact in a pharm tech class. I don't think this would be a surprise to many individuals in the medical field.

 

[MattPsy]

Stay classy, octanol:water partition