Heroin DependenceNarcoticsMorphine DerivativesMethadoneSelf AdministrationBuprenorphineDrug OverdoseCodeineStreet DrugsCocaine-Related DisordersSubstance Abuse, IntravenousBehavior, AddictiveOpioid-Related DisordersSubstance Abuse DetectionDrug and Narcotic ControlSubstance Withdrawal SyndromeNaloxoneCocaineSubstance-Related DisordersNaltrexoneOpiate Substitution TreatmentMorphineReceptors, Opioid, muDrug UsersAnalgesics, OpioidConditioning, OperantCrimeNucleus AccumbensReinforcement (Psychology)Substance Abuse Treatment CentersDose-Response Relationship, DrugSoftwareLaw EnforcementGas Chromatography-Mass SpectrometryReinforcement ScheduleBehavior, AnimalExtinction, PsychologicalDrug ContaminationTime FactorsCommerceAlgorithmsBiological AvailabilityPolitical SystemsCuesCrack CocaineInjections, IntravenousRats, Long-EvansNeedle SharingUnited StatesRisk-TakingSocial Determinants of HealthBaltimoreFlupenthixolHIV InfectionsPupilDrug InteractionsPrisonersReceptors, Opioid, deltaRewardSecobarbitalDrug-Seeking BehaviorSweat