Pain
Fentanyl
Fentanyl is about 80-100 times more potent than morphine and is extremely lipophilic.
If given intravenously its peak analgesic effect occurs about five minutes after administration, which is shorter than other parental opioids such morphine and hydromorphone (3).
Metabolism is via Cytocrome P 450 and it is metabolized to an inactive metabolite, norfentanyl, in the liver and intestinal mucosa.
Excretion is renal and it is safe to use in patients with renal failure.
Fentanyl patches must not to be introduced as the first opioid in the treatment of pain and it cannot be used to manage the pain of opioid naïve children.
Because of a long onset time, inability to rapidly titrate drug delivery and long elimination half-time, transdermal fentanyl is contraindicated for acute pain management. It is better used for chronic and stable pain (2).
Table 3. Dosing Guideline for Fentanyl in Children. (H Siden) (3)
Route |
Younger Child < 50 kg |
Older Child > 50 kg |
Comments |
Response Time |
Duration of action |
IV/SC |
0.5 - 2 mcg/kg q 30 min |
25 - 50 mcg q 30 min |
Administer over at least 3 - 5 min for IV |
1 - 2 min |
|
IV/SC Continuous infusion |
1 - 4 mcg/kg/hr continuous infusion-titrate to effect |
1.5 mcg/kg/hr continuous infusion titrate to effect |
Administer over at least 3-5 min for IV |
1 - 2 min |
|
Transdermal |
Use standard adult conversion tables |
|
|
Serum levels leveling off around 12 hrs |
In some children, especially younger duration is only 48 hrs. |
Sublingual |
0.5 mcg/kg/dose |
25 - 50 mcg |
For activity (incident) pain |
5 - 15 min |
30 - 60 min |
