The most potent analgesic agent is:: (A) Fentanyl, (B) Sufentanil, (C) Remifentanil, (D) Allentanil
Answer is B. Sulfentanil is 5 times more potent than Fentanyl.Alfentanil and remifentanil are faster acting and recovery is rapid. Above three drugs are congeners of Fentanyl. Ref: KD Tripathi 8th ed.