Lofexidine May Enhance Naltrexone Efficacy

The anti-hypertensive medication lofexidine is used commonly in the United Kingdom and less often in the United States to alleviate symptoms of opiate withdrawal. Now, a pilot study by Dr. Rajita Sinha and colleagues at Yale University School of Medicine suggests that lofexidine can enhance success rates among patients taking maintenance naltrexone to avoid relapse to opioids. The researchers stabilized 18 opioid-detoxified men and women on naltrexone (50 mg) and lofexidine (2.4 mg) daily for 1 month. They then retained all the patients on naltrexone for 4 more weeks, but kept 8 on lofexidine and gave 10 others identical-looking pills containing lofexidine doses that—unbeknownst to the patients—tapered to zero over several days. Of the 13 patients who completed the study, 80 percent of those who continued to receive combination therapy submitted opiate-free urine samples throughout the 4-week period, compared with 25 percent of those tapered to placebo. A followup laboratory session that exposed 10 of the patients to stressful and opiate-related stimuli showed that lofexidine—but not placebo—reduced the patients' reaction to stress, stress-induced opiate craving, and negative emotions (such as anger), all of which can trigger relapse.

Psychopharmacology 190(4):569-574, 2007. [Full Text (PDF, 119KB)]