Also known as Alfenta, Rapifen Intensive Care, and Rapifen Concentrate
Alfentanil (R-39209, trade name Alfenta, Rapifen in Australia) 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. It is an agonist at mu opioid receptors.Source: Wikipedia
Patients are most commonly prescribed alfentanil to treat blastomycosis, rabies, west nile virus, and pick disease.