AnalgesicsAnalgesics, OpioidMorphineReceptors, Opioid, muEtorphinePainPain MeasurementNaloxoneAnalgesics, Non-NarcoticAnalgesiaPain, PostoperativeTramadolPhenacetinAcetaminophenDextropropoxypheneAnti-Inflammatory Agents, Non-SteroidalDrug ToleranceCodeinePain ThresholdMeperidineFentanylPentazocinePain ManagementOxycodoneAnesthetics, LocalDipyroneHyperalgesiaInjections, SpinalBupivacaineAnalgesia, EpiduralDouble-Blind MethodAnalgesia, Patient-ControlledCarrageenanKetoprofenKidney Papillary NecrosisTolmetinNefopamReceptors, OpioidHydrocodoneNarcotic AntagonistsKetorolacPain, IntractableIbuprofenNociceptionNeuralgiaHydromorphoneDose-Response Relationship, DrugNalorphineAcupuncture AnalgesiaCyclohexanecarboxylic AcidsBuprenorphineEdemaNociceptorsDiclofenacAnalgesia, ObstetricalButorphanolOxymorphoneMorphine DerivativesMorphinansMeptazinolNociceptive PainHypnotics and SedativesNarcoticsAlfentanilAntipyreticsKetamineAcetic Acid