all five opiates produced analgesia with the relative order of potency being lofentanil greater than carfentanil greater than sufentanil greater than fentanyl greater than alfentanil , and the relative order of duration at comparative doses lofentanil greater than sufentanil greater than carfentanil greater than fentanyl greater than alfentanil .
C0015846
fentanyl
C0002026
alfentanil