BuprenorphineOpioid-Related DisordersNarcotic AntagonistsAnalgesics, OpioidNarcoticsOpiate Substitution TreatmentNaloxoneMethadoneAdministration, SublingualMorphinansHeroin DependenceReceptors, OpioidMorphineNaltrexoneMethadyl AcetateNeonatal Abstinence SyndromeHeroinOpioid PeptidesAnalgesicsFentanylPainSubstance Withdrawal SyndromeHydromorphoneReceptors, Opioid, kappaOxycodoneEnkephalin, MethionineOpiate AlkaloidsPrescription Drug MisusePain MeasurementAnalgesiaEnkephalin, Ala(2)-MePhe(4)-Gly(5)-LevorphanolReceptors, Opioid, muReceptors, Opioid, deltaSubstance Abuse DetectionCodeineChronic PainDose-Response Relationship, DrugNalbuphineTramadolPrescription Drug DiversionEnkephalinsPain, IntractableDrug and Narcotic ControlDiprenorphinePrescription DrugsDrug InteractionsStreet DrugsThiazinesDrug TolerancePain, PostoperativeEndorphinsSubstance-Related DisordersSubstance Abuse Treatment Centersbeta-EndorphinButorphanolEtorphineDrug CombinationsDouble-Blind MethodCyclazocineMeperidineEuphoria