Brifentanil is an opioid

Opioid

An opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract...

 analgesic

Analgesic

An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....

 that is an analogue

Analog (chemistry)

In chemistry, a structural analog , also known as chemical analog or simply analog, is a compound having a structure similar to that of another one, but differing from it in respect of a certain component. It can differ in one or more atoms, functional groups, or substructures, which are replaced...

 of fentanyl and was developed in the early 1990s.

Brifentanil is most similar to highly potent, short-acting fentanyl analogues such as alfentanil

Alfentanil

Alfentanil is a potent but short-acting synthetic opioid analgesic drug, used for anaesthesia in surgery. It is an analogue of fentanyl with around 1/4 the potency of fentanyl and around 1/3 of the duration of action, but with an onset of effects 4x faster than fentanyl...

. The effects of brifentanil are very similar to those of alfentanil, with strong but short lasting analgesia and sedation, and particularly notable itching and respiratory depression.

Side effects of fentanyl analogues are similar to those of fentanyl, and include itching, nausea

Nausea

Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...

 and potentially serious respiratory depression which can be life-threatening. The risk of respiratory depression is especially high with potent fentanyl analogues such as alfentanil and brifentanil, and these drugs pose a significant risk of death if used outside of a hospital setting with appropriate artificial breathing apparatus available.