Administration, OralDrug Administration ScheduleInjections, IntravenousUnited States Food and Drug AdministrationDose-Response Relationship, DrugTime FactorsDrug Administration RoutesRats, Sprague-DawleyRats, WistarAdministration, IntranasalInjections, IntraperitonealDisease Models, AnimalInjections, SubcutaneousMice, Inbred C57BLLiverAdministration, RectalBiological AvailabilityTreatment OutcomeInfusions, IntravenousInjections, IntramuscularAdministration, TopicalHalf-LifeDrug InteractionsAdministration, IntravenousArea Under CurveInjections, IntraventricularDogsRats, Inbred StrainsMice, Inbred BALB CAuthorshipAdministration, CutaneousDouble-Blind MethodTissue DistributionBrainBlood PressureCross-Over StudiesRandom AllocationUnited StatesAdministration, InhalationKidneyBody WeightAdministration, SublingualInfusions, ParenteralAnalysis of VarianceMorphineBehavior, AnimalInjectionsPregnancyInjections, SpinalDrug ToleranceRabbitsRecombinant ProteinsAnalgesics, OpioidPlant ExtractsRNA, MessengerLungOrgan SizeChromatography, High Pressure LiquidMetabolic Clearance RateHemodynamicsMice, Inbred ICRProspective StudiesAntineoplastic AgentsHeart RateRats, Inbred F344Motor ActivityEthanolAnalgesicsSelf AdministrationEstradiolDrug CombinationsMice, KnockoutRetrospective StudiesDrug Therapy, CombinationPain MeasurementImmunohistochemistryMice, Inbred StrainsEnzyme InhibitorsDrug Evaluation, PreclinicalAntibodies, MonoclonalPiperidinesAnti-Inflammatory Agents, Non-SteroidalBlood GlucoseAdministration, BuccalPainSpleenInjections, Intra-ArterialAnesthesiaNeoplasmsDrug SynergismCells, CulturedIntestinal AbsorptionProdrugsNaloxoneDrug ApprovalReproducibility of ResultsCocaineEatingNitric OxideCytokines