Animal models for opioid addiction drug discovery.

INTRODUCTION: Since ancient times, the opium poppy has been used in a variety of settings, including pain management. Natural and synthetic derivatives of opium are commonly used in medicine today and include drugs, such as morphine, codeine, hydromorphone and oxycodone. Although excellent at inhibiting pain, these narcotics often produce a state of euphoria leading to misuse and abuse by the general population, particularly in young adults. The misuse of prescription opiates has continually increased over the past 10 years despite associated negative outcomes, resulting in opiate psychological dependence, withdrawal and relapse.

AREAS COVERED: This paper briefly refers to the history of opiate use and the modern challenges associated with chronic exposure. The authors present the prevalence of addiction and misuse of prescription opiates and discuss some of the opiate-associated effects. This includes activation of reward circuitry and compensatory receptor mechanisms. Finally, the authors provide a review on neuroadaptive changes that manifest during opiate dependence, withdrawal and relapse in animal models.

EXPERT OPINION: In spite of the various methods available to treat opiate addiction, there is still a huge unmet need for its management, including the creative design of novel, non-addictive pain medications. The authors believe that multifunctional compounds or combinations of compounds that inhibit pain pathways, whereas not activating the reward pathways, will begin to subdue the opiate addiction endemic.