Positive Topline Results in Early Phase Study of Investigational Treatment for Opioid Overdose Announced


OPNT003 is a nasal spray that works to reverse respiratory depression from synthetic opioid overdose.

Opiant Pharmaceuticals has announced positive topline results of a pharmacodynamic study conducted to evaluate OPNT003 nasal nalmefene (3 mg nalmefene hydrochloride), the company’s investigational treatment for opioid overdose, according to a press release.1

In a crossover study of healthy volunteers, researchers compared 3 mg nasal nalmefene hydrochloride with 4 mg nasal naloxone hydrochloride to reverse respiratory depression resulting from synthetic opioid remifentanil. Investigators compared changes in minute ventilation after administration of the respective drug; primary endpoint was 5 minutes after administration.

In a preliminary analysis of the 50 study participants, treatment with OPNT003 led to a “greater reversal of respiratory depression that was nearly twice that produced by nasal naloxone at 5 minutes.” For OPNT003 and naloxone, increases in minute ventilation were 5.745 L/min and 3.011 L/min, respectively, and OPTN003 met the primary study endpoint of noninferiority.

Previous positive results were reported from 2 separate pharmacokinetic studies: OPNT003-PK-01 and OPNT003-PK-02. The first study evaluated the pharmacokinetic behavior of nasal nalmefene, while the second evaluated the effect of varying doses.

“The findings from this [pharmacodynamic] study are compelling and add to a body of nonclinical and clinical evidence demonstrating the potential of OPNT003…to offer an important treatment option for opioid overdose,” said Richard C. Dart, MD, PhD, director of the Rocky Mountain Poison & Drug Center, Denver Health and Hospital Authority, and Opiant Scientific Advisory Board member.

“Synthetic opioids, such as fentanyl, are responsible for the great majority of overdoses today, are far more potent, have a more rapid onset, and can have a long duration of action,” Dart added. “They can quickly depress respiration and can continue to deprive the brain of oxygen even after administration of naloxone, the only current FDA-approved treatment for opioid overdose.”

Roger Crystal, MD, president and CEO of Opiant, also commented on the study results. “These data, taken together with our prior [pharmacokinetic] studies, suggest that OPNT003 could be well suited to address the challenges in treating today’s opioid overdoses…[W]e look forward to continuing to work towards submitting our New Drug Application, which we anticipate occurring in the second half of this year,” he said.

OPNT003 is being developed under the 505(b)(2) pathway, and the FDA granted the company a Fast Track Designation for OPNT003 in November 2021.


  1. Opiant Pharmaceuticals announces positive topline results from head-to-head pharmacodynamic study comparing OPNT003, nasal nalmefene, to nasal naloxone. News release. Opiant Pharmaceueticals. April 27, 2022. Accessed May 4, 2022. https://www.globenewswire.com/news-release/2022/04/27/2430661/37234/en/Opiant-Pharmaceuticals-Announces-Positive-Topline-Results-from-Head-to-Head-Pharmacodynamic-Study-Comparing-OPNT003-Nasal-Nalmefene-to-Nasal-Naloxone.html
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