AnalgesicsAnalgesics, OpioidAnalgesics, Non-NarcoticAnalgesiaPainPain MeasurementMorphinePain, PostoperativeTramadolPhenacetinAcetaminophenDextropropoxypheneAnti-Inflammatory Agents, Non-SteroidalDrug ToleranceCodeinePain ThresholdMeperidineFentanylPentazocinePain ManagementReceptors, Opioid, muOxycodoneAnesthetics, LocalDipyroneHyperalgesiaInjections, SpinalBupivacaineAnalgesia, EpiduralNaloxoneStereoisomerismDouble-Blind MethodAnalgesia, Patient-ControlledTropaeolaceaeCarrageenanKetoprofenDose-Response Relationship, DrugKidney Papillary NecrosisPlant ExtractsTolmetinNefopamReceptors, OpioidHydrocodoneNarcotic AntagonistsKetorolacPain, IntractableIbuprofenNociceptionNeuralgiaHydromorphoneNalorphineAcupuncture AnalgesiaCyclohexanecarboxylic AcidsBuprenorphineEdemaNociceptorsMolecular StructureDiclofenacMagnetic Resonance SpectroscopyAnalgesia, ObstetricalButorphanolOxymorphoneAnti-Inflammatory AgentsMorphine DerivativesMorphinansMeptazinolNociceptive PainHypnotics and SedativesNarcoticsAlfentanilAntipyreticsKetamineAcetic AcidNalbuphineMolecular ConformationNucleic Acid ConformationAcute PainNerve BlockChronic PainRats, Sprague-DawleyModels, MolecularDexmedetomidineCyclazocineKetorolac TromethamineSufentanilLidocaineTime FactorsPhytotherapyEndorphinsPiroxicamAminesNitrous OxideClonidineNonprescription DrugsNaltrexoneTreatment OutcomeAmidesReceptors, Opioid, deltaLevorphanolOpioid PeptidesElectroacupuncture