Opioid-blocking Drug May Help Alcoholics

Opioid blocker extended-release injectable naltrexone (XR-NTX) reduces the brain’s response to cues that may cause alcoholics to relapse, according to research at Harvard-affiliated McLean Hospital.

The data was presented at the annual meeting of the American Psychiatric Association by Scott Lukas, PhD, director of the Neuroimaging Center at McLean,Located in Bekmont, Mass. Lukas said the findings help shed some light on how XR-NTX works in reducing the craving for alcohol and potentially helps predict who will respond best to the drug.

"These data are quite important since relapse remains a significant challenge in treating patients with alcohol dependence," Lukas said, in a news release. "It looks to us that XR-NTX can help people remain abstinent by reducing the importance of these cues so they are less likely to relapse."

The drug, which was approved for the treatment of alcohol dependence in 2006, blocks opioid receptors in the brain.

"We were trying to better understand the biological basis of how XR-NTX reduces alcohol consumption," Lukas said, in a release. "These data clearly demonstrate that XR-NTX reduced craving response in the brain when patients were presented with alcohol cues."

Researchers used brain imaging as a tool to document how the drug works when a person is placed in a situation deemed risky for alcohol relapse. The alcohol-dependent individuals, a total of 28, were tested with a Blood Oxygen Level Dependent fMRI scan while shown pictures of bottles or glasses of alcoholic beverages and exposed to the odors of their favorite alcoholic beverages. The double-blind study required that 15 participants be given an injection of XR-NTX and 13 given a placebo injection. First, the subjects were asked to self-report their cravings for alcohol after being exposed to the cues. All reported that their cravings increased in the first few minutes. Those on XR_NTX, however reported that their cravings started to diminish after a few minutes, while those on placebo injection did not experience a decrease.

Additionally, the image scans revealed that the pictures and odors induced sharply contrasting brain blood flow activation patterns in the groups. Scans were taken at baseline again two weeks after the injection and those on placebo remained virtually unchanged. Yet, those on the drug showed significant reductions in activation patterns.

"The areas in the brain associated with craving did not light up nearly as much in patients treated with XR-NTX compared to patients on placebo," Lukas said. "These data suggest that those patients on XR-NTX were responding less strongly to the alcohol cues after being on the drug for only two weeks.”