BuprenorphineAnalgesics, OpioidReceptors, Opioid, muOpioid-Related DisordersNarcotic AntagonistsReceptors, OpioidReceptors, Opioid, deltaReceptors, Opioid, kappaOpiate Substitution TreatmentNaloxoneNarcoticsOpioid PeptidesMethadoneMorphinansAdministration, SublingualNaltrexoneHeroin DependenceMorphineMethadyl AcetateHeroinSubstance Withdrawal SyndromeNeonatal Abstinence SyndromeEnkephalin, Ala(2)-MePhe(4)-Gly(5)-EnkephalinsAnalgesicsDiprenorphineLevorphanolHydromorphonePain MeasurementPrescription Drug MisuseOpiate AlkaloidsPainAnalgesiaFentanylDose-Response Relationship, DrugSubstance Abuse DetectionNalbuphineEnkephalin, D-Penicillamine (2,5)-EndorphinsDynorphinsbeta-EndorphinButorphanolDrug ToleranceThiazinesEnkephalin, LeucineDrug InteractionsPrescription Drug DiversionSubstance Abuse Treatment CentersCyclazocineDrug and Narcotic ControlTramadolEnkephalin, Leucine-2-AlanineEthylketocyclazocineCodeineStreet DrugsChronic PainBenzomorphansPain, PostoperativeDrug CombinationsDouble-Blind MethodSubstance-Related DisordersPain, Intractable