Remifentanil is :

Remifentanil is shortest acting opioid due to its metabolism by plasma esterases. Due to its short duration of action, it is indicated for short-term painful procedures. Intravenous bolus dosing is not practical because of the short duration of action, rather it is administered by constant i.v. infusion. Potency is equal to fentanyl and similarly, it can also cause post-operative muscle rigidity.