Caroline Cassels

May 30, 2013

SAN FRANCISCO — A novel, experimental intranasal spray formulation of naloxone is showing promise for the treatment of binge eating disorder (BED), preliminary research suggests.

Results from a phase II, randomized, double-blind, placebo-controlled trial presented here at the American Psychiatric Association's 2013 Annual Meeting showed that intranasal naloxone spray produced a significantly greater reduction than placebo in time spent binge eating (P = .024).

"The findings are encouraging, and if this works out, it would be a big advance [in the treatment of BED]. But this is the very first study, so it is still too soon to tell. But it could be very good," study investigator Hannu Alho, MD, PhD, from the University of Helsinki, in Finland, told Medscape Medical News.

Characterized by recurrent bingeing episodes, patients with BED feel a loss of control over their eating. Unlike bulimia, it is not followed by purging, excessive exercise, or fasting, and as a result, individuals with BED are often overweight or obese. According to the National Institute of Mental Health, the lifetime adult prevalence of BED is about 2.8% of the US adult population.

An opioid antagonist, naloxone is currently approved by the US Food and Drug Administration (FDA) to reverse the effects of opioid poisoning and is administered via injection.

Other opioid antagonists, such as naltrexone and nalmefene, have been shown to be effective in alcohol dependence, reducing the frequency of drinking as well as relapse rates.

Although the FDA recommends that these medications be taken only during abstinence from alcohol, David Sinclair, MD, the current study's principal investigator, has successfully used it to treat alcohol dependence by having patients take the medication immediately before drinking to reduce alcohol craving and consumption over time.

Dr. Hannu Alho

Dr. Alho explained that this process, known as "pharmacological extinction," was first developed by Dr. Sinclair at the University of Helsinki in the 1990s and works by blocking endorphins that activate the opioid system and reinforce addictive behavior.

Building on this principal, the investigators sought to determine whether the naloxone intranasal spray would reduce bingeing behavior in BED patients.

Fast Acting

The 24-week study included 127 adults who met Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria for BED. The majority of the patients were women and ranged in age from the mid-30s to mid-50s. They were recruited via an advertisement in a local magazine. With a mean body mass index (BMI) of 32, most were obese to severely obese.

Unlike alcohol cravings, which can be constant, the urge to binge has a rapid onset. The naloxone intranasal spray acts within minutes, selectively targeting the extinction of the harmful eating behavior, the investigators note.

Moreover, naloxone exerts its effects for 2 hours, which is the typical duration of a binge, they add.

Participants were instructed carry the spray on their person and to administer it (up to a maximum of 4 mg per day) prior to bingeing.

The study's primary outcomes were the mean minutes spent binge eating and the mean scores on the standard 16-item Binge Eating Scale (BES).

Overall, 81% of the study participants completed the study. There was no statistically significant difference in dropout rates between the 2 study groups, and there were no serious adverse events.

From baseline, the reduction in time spent bingeing was 75% (125 minutes) in the naloxone group vs 62% (84 minutes) in the placebo group.

In addition, patients taking naloxone experienced a small but significant decrease in BMI from week 12 to week 24 of the study (P = .015), as well as a statistically significant reduction in the percentage of body fat (P = .004).

The strong placebo effect was typical and was as expected for this patient population, said Dr. Alho. He speculated that the difference in outcomes between the 2 groups would likely have been greater if the study duration had been longer.

Interesting Hypothesis

Commenting on the study for Medscape Medical News, Evelyn Attia, MD, director of the Center for Eating Disorders at New York–Presbyterian Hospital, in New York City, said the study presents an intriguing idea.

Dr. Evelyn Attia

The idea that there may be some addictivelike properties to a binge eating episode is interesting, and the question of whether something that blocks our opioid receptors might change the experience of, and the desire to engage in, those behaviors is certainly an interesting hypothesis," said Dr. Attia.

She noted that the results were "mixed" and that although the findings suggest there may be an ability to limit the amount of time spent engaging in bingeing behavior, "all it really tells us at this point is that maybe there is a bit of a hint of something that may warrant some additional attention," she said.

Echoing Dr. Alho, Dr. Attia also noted that the study's "very high" placebo response rate is typical in this patient population.

Dr. Attia added that larger, non-industry-sponsored trials that examine the frequency of binge eating episodes as well as the duration of time patients engage in an episode would be helpful.

"Duration [of a binge eating episode] is harder to evaluate and may not be as important to an affected individual as whether the episode occurs at all," she said.

The study was sponsored by Lightlake Therapeutics Inc. Dr. Alho and Dr. Attia report no relevant financial relationships.

The American Psychiatric Association's 2013 Annual Meeting. Abstract NR4-29. Presented May 19, 2012.

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