MethadoneNarcoticsOpiate Substitution TreatmentOpioid-Related DisordersHeroin DependenceMethadyl AcetateBrain ChemistryAnalgesics, OpioidBuprenorphineBrain InjuriesNeonatal Abstinence SyndromeBrain NeoplasmsHeroinBrain MappingSubstance Abuse DetectionBrainPyrrolidinesBrain EdemaDrug OverdoseBrain StemMorphineBrain IschemiaNarcotic AntagonistsSubstance Withdrawal SyndromeSubstance Abuse, IntravenousDextropropoxypheneStreet DrugsSubstance-Related DisordersMagnetic Resonance ImagingCocaine-Related DisordersOpiumBrain AbscessDose-Response Relationship, DrugStereoisomerismOxidoreductases, N-DemethylatingNaloxoneMeconiumDrug InteractionsTherapeutic CommunityTime FactorsNeuronsDirectly Observed TherapyHypoxia, BrainPrisonersCocaineBlood-Brain BarrierCerebral CortexNaltrexoneRats, Sprague-DawleyCodeine