The present invention relates to a method of treating drug addiction and reducing dependence or tolerance on a dependence-inducing opiate drug, wherein the method comprises administering to a subject a compound having the structure of formula (I):having the IUPAC name of (−；)3-((S)-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)(3-thienyl)methyl)phenol, or pharmaceutically acceptable esters or salts thereof, wherein the compound has activity on the mu, delta and kappa opioid receptors thereby providing added analgesia with an improved therapeutic index and reduced risk of respiratory depression.
