A study by a team of University of Kentucky researchers has shed new light on the potential habit-forming properties of the popular pain medication tramadol, in research funded by the National Institute on Drug Abuse. The paper is slated to appear in an upcoming edition of the academic journal Psychopharmacology.
Prescription pain killer abuse is a major public health problem in the U.S. In 2010, more individuals over the age of 12 reported nonmedical use of prescription pain relievers in the past month than use of cocaine, methamphetamine or heroin.
"Prescription pain pill abuse is a real problem in Kentucky. We have lots of overdoses. We held a summit here in February specifically about partnering law enforcement and medicine to tackle this problem," said lead study author William W. Stoops of the UK College of Medicine Department of Behavioral Science, the UK Center on Drug and Alcohol Research (CDAR) and the UK College of Arts and Sciences Department of Psychology.
Other UK authors include: Michelle R. Lofwall, Paul A. Nuzzo, Lori B. Craig, Anthony J. Siegel and Sharon L. Walsh.
The study utilized a double-blind, placebo-controlled design. Participants were given one of 12 possible dose combinations of placebo, tramadol, naltrexone and hydromorphone. Naltrexone is an opioid receptor blocker, used to attenuate the effects of opioid medications. Following drug administration, participants were evaluated based on self-reported measures, observer-reported measures, ocular measurements (such as pupil dilation) and performance tasks. Ten participants completed the study.
It was expected that if both tramadol and hydromorphone (Dilaudid-), a common opioid analgesic, acted similarly upon the nervous system, administering naltrexone would mitigate the effects of both drugs in a similar fashion. What was found was that while participants given both hydromorphone and naltrexone reported a lack of influence by the drug, patients taking tramadol and naltrexone reported still feeling "high". Participants who received hydropmorphone or tramadol with placebo also reported feeling affected.