Administration, OralDrug Administration ScheduleInjections, IntravenousUnited States Food and Drug AdministrationDose-Response Relationship, DrugDrug Administration RoutesTime FactorsRats, Sprague-DawleyRats, WistarAdministration, IntranasalInjections, IntraperitonealDisease Models, AnimalInjections, SubcutaneousLiverMice, Inbred C57BLAdministration, RectalBiological AvailabilityInjections, IntramuscularAdministration, TopicalInfusions, IntravenousHalf-LifeAdministration, IntravenousDrug InteractionsArea Under CurveInjections, IntraventricularRats, Inbred StrainsMice, Inbred BALB CTissue DistributionDogsAdministration, CutaneousTreatment OutcomeDouble-Blind MethodBrainCross-Over StudiesBlood PressureKidneyAdministration, SublingualAdministration, InhalationInfusions, ParenteralBody WeightRandom AllocationBehavior, AnimalAnalysis of VarianceRecombinant ProteinsDrug ToleranceMorphineRNA, MessengerPregnancyInjectionsRabbitsPlant ExtractsChromatography, High Pressure LiquidOrgan SizeInjections, SpinalMetabolic Clearance RateLungMice, Inbred ICRRats, Inbred F344Motor ActivityAnalgesics, OpioidHeart RateEthanolSelf AdministrationAntineoplastic AgentsEstradiolMice, KnockoutDrug CombinationsHemodynamicsMice, Inbred StrainsUnited StatesDrug Evaluation, PreclinicalEnzyme InhibitorsAnalgesicsDrug Therapy, CombinationAntibodies, MonoclonalSpleenPiperidinesBlood GlucoseIntestinal AbsorptionDrug ApprovalInjections, Intra-ArterialAdministration, BuccalAnti-Inflammatory Agents, Non-SteroidalProdrugsCells, CulturedDrug SynergismEatingKineticsCocaineImmunohistochemistryNaloxoneDopamineNitric OxideCytokinesGenetic TherapyAbsorptionPainInsulinHydrocortisoneAnti-Bacterial Agents