Preclinical evidence of new opioid modulators for the treatment of addiction.

IMPORTANCE OF THE FIELD: Addiction to opiates is one of the most severe forms of substance dependence, and despite a variety of pharmacological approaches to treat it, relapse is observed in a high percentage of subjects. New pharmacological compounds are necessary to improve the outcome of treatments and reduce adverse side effects. Moreover, drugs that act on the opioid system can also be of benefit in the treatment of alcohol or cocaine addiction. AREA COVERED BY THIS REVIEW: Recent preclinical studies of pharmacological agents for the treatment of opiate addiction (2008 to the present date). WHAT THE READER WILL GAIN: The reader will be informed of the latest drugs shown in animal models to modify dependence on opiates and the reinforcing effects of these drugs. In addition, reports of the latest studies to test these compounds in models of other drug addictions are reviewed. TAKE HOME MESSAGE: The classic clinical pharmacotherapy for opiate dependence, involving mu-opioid receptor agonists or antagonists, has not yielded a high success rate in humans. In pharmacotherapy for opioid dependence, new options are emerging and different pharmacological strategies are now being tested.