sentence: The relative order of potency ( opioid receptor subtype , IC in nmol / L ± SEM ) was DADLE ( δ , 13.9 ± 2.1 ) ≥ met-enkephalin ( δ , 17.9 ± 3.3 ) ≥ dynorphin A ( κ , 19.5 ± 4.0 ) ≥ DAMGO ( μ , 23.3 ± 4.1 ) > morphine ( μ , 230 ± 13 ) and morphiceptin ( μ , 403 ± 19 ) .