Фентанил

Pale Brown Solid

Fentanyl is available in a variety of preparations for parenteral, transdermal and transmucosal (including buccal) administration. Because of high firstpass metabolism (~70%) it is not given orally. It is approximately 80–100 times more potent than morphine in the acute seing, although it is approximately 30–40 times as potent when given chronically (e.g. slowrelease transdermal patches). With transdermal administration, the patch and underlying dermis act as a reservoir, and plasma concentration does not reach steady state until approximately 15h after initial application. Plasma concentration also declines slowly after removal (t1/2 ~15–20 h).
Fentanyl is very lipophilic, with a relatively short duration of action. There are several new buccal/transmucosal preparations developed for rapid-onset breakthrough pain. These aim to have a very rapid onset in approximately 10min, although this may not be the case in clinical practice. Fentanyl has a large VD with rapid peripheral tissue uptake, limiting initial hepatic metabolism. This may result in significant variability in plasma concentrations and secondary plasma peaks. It binds to αl-acid glycoprotein and albumin; 40% of the protein-bound fraction is taken up by erythrocytes. The lungs may be important in exerting a first-pass effect on fentanyl (up to 75% of the dose), thus buffering the plasma from high peak drug concentrations.

ChEBI: The carboxamide resulting from the formal condensation of the aryl amino group of N-phenyl-1-(2-phenylethyl)piperidin-4-amine with propanoic acid.

When the 4-phenyl substituent of meperidine was replaced with a 4-aniline with a nitrogen connection, the potency increased. This led to the development of the 4-anilidopiperidine series of compounds. Fentanyl (Sublimaze) was the first compound marketed and was found to be almost 500 times more potent than meperidine. The high lipophilicity of fentanyl gave it a quick onset, and the quick metabolism led to a short duration of action. The combination of potency, quick onset, and quick recovery led to the use of fentanyl as an adjunct anesthetic.

Toxic.

In addition to all of the adverse effects and contraindications previously described for morphine, the following contraindications apply specifically to these drugs. They are contraindicated in pregnant women because of their potential teratogenic effects. They also can cause respiratory depression in the mother, which reduces oxygenation of fetal blood, and in the newborn; the incidence of sudden infant death syndrome (SIDS) in the newborn is also increased.
Cardiac patients need to be monitored closely when receiving these drugs because of their bradycardiac effects (which can lead to ectopic arrhythmias), and hypotensive effects resulting from prolonged vasodilation. In addition, the drugs stiffen the chest wall musculature, an effect reversed by naloxone.

Poison by intraperitoneal routes. Human systemic effects by intravenous route: somnolence, respiratory depression. When heated to decomposition it emits toxic fumes of NOx.