20.03.5.3 Fentanyl

Fentanyl is the opioid commonly preferred by anaesthesiologists as an adjunct to general anaesthesia. It is preferred because it is easy to manage. It has a short time to peak analgesic effect (about 5 minutes) and rapid termination of effect after intravenous bolus doses are stopped.

Decreases in blood pressure can be a problem with the opioids. Fentanyl is preferred by anaesthesiologists as it has relative cardiovascular stability i.e. does not have major effects on blood pressure.

Fentanyl is administered epidurally and intrathecally for acute postoperative and chronic pain management.

Fentanyl is highly lipid soluble and rapidly cross blood brain barrier. Fentanyl, like all highly lipid soluble drugs, is initially distributed to the highly perfused tissues. Then, it is redistributed from highly perfused tissues to those with lower perfusion (muscle and fat).

Fentanyl undergoes hepatic metabolism and kidney excretion. There are no active (toxic) metabolites of fentanyl, and consequently, it can be used in renal impairment, whereas other opioids (e.g. morphine) are difficult to use in renal impairment.