Remifentanil is a potent intravenous short-acting synthetic opioid. It acts as a µ-receptor agonist. Remifentanil is rapidly hydrolyzed by plasma and tissue esterases. It is unique in that it displays no context-sensitivity. In other words, it does not accumulate with prolonged infusion. The context-sensitive half-life is ~4 minutes. It is useful for procedures requiring profound analgesia and rapid emergence, such as neurosurgical and otolaryngology procedures. It is typically administered as an infusion but bolus doses are very effective for brief noxious stimuli. Caution must be taken when using remifentanil in non-intubated patients as it is a potent respiratory depressant and can cause muscle rigidity with inability to mask ventilate.