Opioid Antagonists

From Reversing Opioid Overdose to Treating Alcohol Use Disorder

Opioid antagonists are a class of compounds that selectively bind to opioid receptors, a critical component of the brain’s reward circuitry. Well known to be safe, they block the ability of opioid drugs (analgesics such as morphine and illicit opioids such as heroin) and endogenous opioid-like peptides (endorphins) that activate the brain’s opioid receptors.

Thus, opioid antagonists can regulate the reward circuitry by reducing or inhibiting behaviors (e.g., craving and reward) triggered when opioid receptors are activated by, for example, opioid drugs or alcohol (which stimulates the release of endogenous opioids). Because both endogenous opioid-like peptides and opioid drugs modulate dopamine release, opioid antagonists can also help manage dopamine-mediated behaviors such as craving.

Current Programs and Candidates

Based on this well-established science, we use opioid antagonists in two of our product candidates (OPNT002 and OPNT006) to treat AUD and OUD, respectively. Opioid antagonists are also vital for reversing the symptoms of opioid overdose, including respiratory depression, that can prove fatal if not treated. Our marketed product, NARCAN® Nasal Spray, and one pipeline product candidate address this issue of national importance.

We have also taken a biological approach to treat OUD by licensing a novel heroin vaccine from WRAIR and NIDA. Rather than blocking the brain’s opioid receptors, antibodies formed in response to the heroin sequester heroin in the blood, preventing it from entering the brain.