MethadoneNarcoticsOpiate Substitution TreatmentOpioid-Related DisordersHeroin DependenceMethadyl AcetateBrain ChemistryAnalgesics, OpioidBuprenorphineBrain InjuriesNeonatal Abstinence SyndromeBrain NeoplasmsHeroinAffectBrain MappingBrainSubstance Abuse DetectionIrritable MoodPyrrolidinesBrain EdemaDrug OverdoseSubstance-Related DisordersBrain StemSubstance Withdrawal SyndromeMorphineBrain IschemiaNarcotic AntagonistsStreet DrugsMagnetic Resonance ImagingSubstance Abuse, IntravenousDextropropoxypheneCocaine-Related DisordersDose-Response Relationship, DrugOpiumBrain AbscessTime FactorsBipolar DisorderStereoisomerismOxidoreductases, N-DemethylatingNaloxoneDrug InteractionsMeconiumPainNeuronsTherapeutic CommunityNaltrexoneDepressionCerebral CortexAnalysis of VarianceRats, Sprague-DawleyDirectly Observed TherapyAntimanic AgentsCocaineHypoxia, BrainPrisonersBlood-Brain BarrierCodeineTreatment OutcomeReceptors, Opioid, mu