When it comes to the successful treatment of opioid use disorder, there are two categories of pharmaceutical drugs that are key to achieving favorable long- and short-term results. Maintenance medications, like buprenorphine, can help a patient avoid cravings and reduce the risk of relapse. Opioid reversal medications are used to protect an individual in the event of an overdose, which can happen easily during relapse or as an accident during regular use.
Opioid overdose reversal medications can help a patient’s respiratory and central nervous systems stabilize and function healthily after an overdose. The most common overdose reversal medication is naloxone, and it’s used as a harm reduction tool across the country to save lives. In August 2024, the United States Food and Drug Administration (FDA) approved a new treatment option: the nalmefene auto-injector. Here’s what this development means for people who use opioids.
What is nalmefene?
While nalmefene auto-injectors have only recently been approved by the FDA, they aren’t new. In 1995, the agency approved nalmefene hydrochloride as a prescription injection under the brand name Revex, but Revex was eventually discontinued. For a long time, nalmefene wasn’t widely available.
Now available under the brand names Opvee® and Zurnai™, nalmefene is an opioid antagonist. That means it bonds with the opioid receptors of the brain even more strongly than opioids do. It can essentially kick opioids out of the receptors they’ve bonded to in the brain and stop the drugs from producing physical effects.
In May 2023, a nasal spray form of nalmefene received FDA approval under the brand name Opvee. This spray is available for use in individuals ages 12 and older and is only available by prescription in a 2.7mg dose. In August 2024, Zurnai nalmefene auto-injectors containing a single 1.5-milligram dose were approved for prescription use in adults and children over the age of 12.
What is nalmefene used for?
For the most part, nalmefene is an emergency medication administered directly by medical professionals as a method of reversing an opioid overdose. Nalmefene can be delivered nasally or via injection.
During an opioid overdose, a person’s blood pressure may drop, and their breathing may slow dramatically or even stop. This is a natural mechanism of opioids, which operate as CNS and respiratory depressants. By forcing opioids out of the brain, nalmefene can restore normal breathing and heart rate. Patients experiencing an opioid overdose who have nalmefene administered to them typically regain normal breathing within two to five minutes.
Nalmefene can also be given to patients who have received a course of opioids as part of surgery. In this case, the opioids are used intentionally as a sedative, and the application of nalmefene helps wake the person up.
Nalmefene has a half-life of approximately 11 hours, which means it can stay in the body and keep opioids from taking effect for many hours. Usually, these effects last long enough for any opioids to be fully processed so there is less risk of an overdose happening again once the nalmefene wears off.
Because of its efficacy and relative safety, nalmefene may eventually become a critical tool for harm reduction groups across the country. For the time being, however, both the nasal spray and auto-injector are only available to medical professionals and as prescriptions.
For those who do have a prescription for nalmefene, it’s important that the patient themself and their friends and loved ones know how to properly administer the drug. For auto-injectors, the process is similar to administering an EpiPen. All you have to do is hold the auto-injector against the patient’s thigh, and the device will do the work for you.
Nasal sprays are also simple to use. With a finger on each side of the device, insert the tip into the patient’s nose until your fingers are touching their nostril. Then use your thumb to firmly depress the plunger. This immediately dispenses the medicine.
No matter what form of nalmefene you’re using, it’s crucial to call 911 immediately after use. The patient may wake up and seem normal, but they should always be examined and monitored by a medical professional to ensure there are no complications.
Nalmefene vs. naloxone
Nalmefene is the newest harm reduction drug to earn FDA approval, but it’s not the only one. Naloxone has been used for decades and is best known by the brand name Narcan. This opioid antagonist and opioid overdose reversal medication was made available over the counter in March 2023 and has become increasingly available in communities throughout the country, though its ease of accessibility varies by state. Its over-the-counter formulation is a nasal spray, and it’s administered the same way that nalmefene in Opvee form is.
Nalmefene and naloxone are highly similar in use and function. So why is there a need for two different opioid overdose reversal drugs? Do they have any differences at all?
There are some nuanced differences between nalmefene and naloxone. Having multiple effective treatment options means medical professionals can better tailor treatments to a patient’s needs.
The biggest difference between the two is their half-life. Nalmefene has a half-life of 11 hours, but naloxone loses potency much quicker and has a half-life of only 2 hours. Because some opioids are long lasting, it’s possible for a patient whose overdose has been reversed with naloxone to relapse into overdose after a couple of hours pass. This is incredibly dangerous, especially if the patient isn’t being monitored closely by medical personnel.
Neither naloxone nor nalmefene is significantly faster than the other in most contexts, but some research suggests that nalmefene acts more quickly when used on an overdose caused by remifentanil.
Naloxone is the only opioid antagonist that’s approved for use on people of all ages, and there are some downsides to nalmefene’s long half-life. Namely, the reduced risk of secondary relapse may discourage individuals from seeking medical attention after an overdose. Nalmefene may also be more likely to cause precipitated withdrawal, which can be both uncomfortable and dangerous.
At the end of the day, both medications are useful and necessary; as with any medication, there are potential risks and contraindications to consider. But having access to both helps medical professionals make informed decisions about their patients’ treatment needs.
Active research that drives better patient care
Ophelia’s clinical team is made up of more than hands-on doctors, nurses, and physician assistants. These medical professionals also contribute to a growing body of research that pushes OUD care forward. From the benefits of telehealth for patient outcomes to the latest medication treatment options, we share original research and publications to increase awareness and help providers better connect with their patients. As the field of opioid treatment evolves, we want to be sure people have access to accurate, up-to-date information about their options.
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