Opiant Pharmaceuticals, Inc.  announced that the first patient has been dosed in a Phase 2 clinical trial of OPNT002, nasal naltrexone, for the treatment of Alcohol Use Disorder (“AUD”). The trial will determine whether OPNT002 reduces heavy drinking as measured by a change in the World Health Organization (“WHO”) drinking risk levels. Clinical and preclinical studies have shown that alcohol releases endorphins, which are the brain's endogenous opioids.

These endorphins are thought to activate opioid receptors, which contribute to alcohol's reinforcing and addictive properties. Current naltrexone treatments work to block mu-opioid receptors when administered orally or through injection. However, converging lines of evidence indicate that activation of delta-opioid receptors also contributes to the reinforcing properties of alcohol.

The effective blockade of delta-opioid receptors requires much higher plasma naltrexone concentrations than is achieved by currently approved naltrexone products. Opiant is developing OPNT002 to rapidly increase plasma concentrations of the drug following dosing and thereby block mu and delta-opioid receptors. In previous research, OPNT002 has demonstrated rapid nasal absorption, delivering high levels of naltrexone yet with a short half-life.

Results from Phase 1 studies demonstrate that OPNT002 produces maximum plasma concentrations that are approximately 50% higher than orally administered naltrexone. This feature, along with a very rapid onset and a short plasma half-life, are characteristics ideally suited to developing OPNT002 for ‘as needed' nasal dosing in anticipation of drinking, or once drinking has started2,3. The primary end point will be the proportion of subjects showing an improvement in WHO Drinking Risk Level consisting of a 2-level reduction from Baseline to end of treatment. WHO Drinking Risk Level will be evaluated in the 28 days prior to the Baseline and end of treatment visits.

The trial is a randomized, double-blind, placebo-controlled study that will enroll approximately 300 patients at sites within the European Union and the United Kingdom. The trial features a Sequential Parallel Comparison Study Design (“SPCD”) aiming to reduce placebo response. Results from the trial are expected in 2023.