PenicillamineEnkephalinsMorphineEnkephalin, MethionineEnkephalin, LeucineGold Sodium ThiomalateEnkephalin, Ala(2)-MePhe(4)-Gly(5)-Enkephalin, Leucine-2-AlanineEnkephalin, D-Penicillamine (2,5)-Hepatolenticular DegenerationS-Nitroso-N-AcetylpenicillamineEndorphinsMorphine DependenceMorphine DerivativesSulfasalazineNaloxoneAnalgesics, OpioidAurothioglucoseReceptors, Opioid, muArthritis, RheumatoidAuranofinReceptors, OpioidTartratesCystinuriaReceptors, Opioid, deltaDimercaprolDrug EruptionsNarcoticsChelating AgentsOrganogold CompoundsBlood SedimentationAntimonyDrug ToleranceNarcotic AntagonistsNitric Oxide DonorsSulfhydryl CompoundsAminopropionitrileMyasthenia GravisCopperSchistosomicidesGoldNaltrexoneDynorphinsCyclazocineDose-Response Relationship, DrugAzathioprineEthylketocyclazocineAnalgesicsInjections, SpinalNitric OxideBenzomorphansProteinuriaAnalgesiaReceptors, Opioid, kappaPain MeasurementTime Factors