The U.S. Food and Drug Administration (FDA) has given the green light to a new nasal spray designed to counteract the effects of opioid overdoses that have worsened during the ongoing drug crisis. The drug, called Opvee, is a variation of nalmefene, a medication that inhibits opioid receptors in the brain, effectively blocking the effects of opioids and restoring normal breathing and blood pressure in those who have recently overdosed.

The nasal spray form of the drug, created by Opiant Pharmaceuticals and now owned by opioid addiction medication manufacturer Indivior, is designed to last longer than other drugs like Narcan, the leading brand of naloxone nasal spray. Experts suggest that fentanyl and other synthetic opioids, which remain in the body longer than other opiates, could be more effectively counteracted by nalmefene-based drugs like Opvee.

While Opvee has demonstrated approximately the same efficacy as Narcan, some experts are worried about the longer-acting nature of the drug. Naloxone withdrawal symptoms can last anywhere from 30 to 40 minutes, but with nalmefene, those same symptoms can persist for six hours or more, requiring additional treatment and management.

Federal grants totaling over $18 million funded Opvee’s development and testing by a team of pharmaceutical researchers and National Institutes of Health scientists working on a medication that would quickly restore breathing while providing protection against relapse.

About 109,000 individuals will have been killed by fentanyl and other synthetic opioids by 2020, making them the new heroin and prescription opioids.

Naloxone is available from pharmacies and carried by police, fire departments, and other emergency personnel across the country.

Opvee, which Indivior has not yet priced, may generate annual sales of $150 million to $250 million. Naloxone will have competition.