MorphineAlkaloidsAnalgesicsAnalgesics, OpioidErgot AlkaloidsMorphine DerivativesMorphine DependenceIndole AlkaloidsPyrrolizidine AlkaloidsVinca AlkaloidsAnalgesics, Non-NarcoticCinchona AlkaloidsAnalgesiaDrug TolerancePain MeasurementBerberine AlkaloidsReceptors, Tumor Necrosis FactorNaloxoneNarcoticsPain, PostoperativeReceptors, Opioid, muAmaryllidaceae AlkaloidsNarcotic AntagonistsCodeineAconitumInjections, SpinalTramadolAporphinesClavicepsBenzylisoquinolinesReceptors, OpioidDose-Response Relationship, DrugFentanylDelphiniumPlant ExtractsAnalgesia, Patient-ControlledCatharanthusPentazocineOxycodonePain ThresholdMeperidineNalorphinePapaverSubstance Withdrawal SyndromeMorphinansAcetaminophenOpiumPhenacetinHydromorphoneSolanaceous AlkaloidsNaltrexoneAnalgesia, EpiduralBerberineRats, Sprague-DawleyAnti-Inflammatory Agents, Non-SteroidalDextropropoxypheneHyperalgesiaMolecular StructureBupivacaineNeotyphodiumNalbuphineAnesthetics, LocalDouble-Blind MethodSucroseCoptisDipyroneRutaceaePlant PoisoningEnkephalin, Ala(2)-MePhe(4)-Gly(5)-OxymorphoneEnkephalinsPeriaqueductal GrayErgotamineStereoisomerismHeroinPain, IntractableRubiaceaeErgotismLycopodiumKetorolacHydrocodonePain ManagementLysergic AcidBuprenorphineEndorphinsThebaineBehavior, AnimalNociceptorsTolmetinEphedraNociceptionCarrageenanBelladonna AlkaloidsSpinal CordHarmineDrug InteractionsEtorphinePlants, MedicinalPlant BarkReceptors, Opioid, kappa