among drugs having an analgesic action in man , 1- ( beta-diethyl-aminoethyl ) -2- ( p-ethoxybenzyl ) -5-nitrobenzimidazole , methadone , morphine , pethidine and codeine ( in descending order of potency ) were active in this test in guinea-pigs .
C0026549
morphine
C0009214
codeine