Prescription medicine
Nalmefene Brand names: Opvee, Zurnai; first approved as Revex
Nalmefene (Opvee) is a prescription medicine with an FDA approval on record since 1995. A generic is approved and listed by 2 labelers, but in the October 7, 2026 NADAC survey pharmacies bought only the brand, at $46.79 per unit (Opvee 2.7 mg nasal spray).
- Generic approved
Check it at the source: the nalmefene FDA label on DailyMed (effective December 8, 2023, Chengdu Shuode Pharmaceutical Co., Ltd); the NDA 20459 record on Drugs@FDA; every nalmefene label on DailyMed.
Highlights of the record
FDA label of December 8, 2023; NDC Directory, Drugs@FDA and Orange Book, October 8, 2026; NADAC October 7, 2026
Used for
From the label: indications and usageNalmefene Hydrochloride Injection is indicated for the complete or partial reversal of opioid drug effects, including respiratory depression, induced by either natural or synthetic opioids.
Forms and strengths
- 2.7 mg
- 0.1 mg/ml
- 1 mg/ml
- 1.5 mg/.5ml
- 2 mg/2ml
Injection (solution); solution; spray.
On the market
- Earliest approval on file
- April 17, 1995 Revex, Hikma; Drugs@FDA’s file, where older or withdrawn approvals can be missing
- Generic approvals
- 2 first February 8, 2022; 2 with a marketed status in Drugs@FDA
- Labelers listed (NDC)
- 3 of which 2 under generic applications, 2 under brand applications, repackagers included
- Last listed patent
- August 4, 2042 Opvee spray; not a generic launch date
Supply and safety
- Pharmacy cost (NADAC)
- $46.79 per unit Opvee 2.7 mg nasal spray
- Shortage (FDA)
- No current entry
- Recalls by its makers (FDA)
- No recall recorded
- FAERS reports
- 40 through July 30, 2026
What is nalmefene used for?
From the label: indications and usageNalmefene Hydrochloride Injection is indicated for the complete or partial reversal of opioid drug effects, including respiratory depression, induced by either natural or synthetic opioids. Nalmefene Hydrochloride Injection is indicated in the management of known or suspected opioid overdose.
FDA pharmacologic class: Opioid Antagonist.
Source: FDA drug label (nalmefene hydrochloride), Chengdu Shuode Pharmaceutical Co., Ltd, effective December 8, 2023 (SPL set 22d67228-6c24-47ca-afc7-52ef279520a0), via openFDA; the full label on DailyMed
What does the patient leaflet for nalmefene say first?
The FDA-approved Medication Guide or Patient Information that comes with the medicine, in its own words.
From the patient leaflet: What is the most important information I should know about ZURNAI?ZURNAI is used to temporarily reverse the effects of opioid medicines. The medicine in ZURNAI is not expected to have an effect in people who are not taking opioid medicines. Always carry ZURNAI with you in case of an opioid emergency. Use ZURNAI right away if you or your caregiver think signs or symptoms of an opioid emergency are present, even if you are not sure, because an opioid emergency can cause severe injury or death. Signs and symptoms of an opioid emergency may include: unusual sleepiness and you are not able to awaken the person with a loud voice or by rubbing firmly on the middle of their chest (sternum). breathing problems including slow or shallow breathing in someone difficult to awaken or who looks like they are not breathing. the black circle in the center of the colored part of the eye (pupil) is very small, sometimes called 'pinpoint pupils,' in someone difficult to awaken. Family members, caregivers, or other people who may have to use ZURNAI in an opioid emergency should know where ZURNAI is stored and how to give ZURNAI before an opioid emergency happens. Make sure everyone reads the information contained in the carton as soon as you receive ZURNAI. Call 911 or get emergency medical help right away after giving the first dose of ZURNAI. Rescue breathing or CPR (cardiopulmonary resuscitation) may be given while waiting for emergency medical help. The signs and symptoms of an opioid emergency can return after ZURNAI is given. If this happens, give additional doses of ZURNAI every 2 to 5 minutes using a new ZURNAI auto-injector for each dose and watch the person closely until emergency help arrives.
From the patient leaflet: How should I store ZURNAI?Store ZURNAI at room temperature between 68°F to 77°F (20°C to 25°C). Do not freeze or refrigerate. Store ZURNAI in a clean dry place. Protect from light. Keep ZURNAI in the carton until use. During storage, check ZURNAI through the viewing window of the auto-injector every 30 days. The liquid should be clear, colorless to light yellow. If the ZURNAI liquid is discolored, cloudy, or contains solid particles, replace it with a new ZURNAI. Check the expiration date. Replace ZURNAI before the expiration date. Keep ZURNAI and all medicines out of the reach of children.
Source: FDA drug label (Zurnai), Knoa Pharma LLC, effective July 31, 2026 (SPL set a59a5847-9fe4-4341-a203-be0a5e6d3e36), via openFDA; the full label on DailyMed
Is there a generic for nalmefene (Opvee)?
The FDA approved the first generic nalmefene on February 8, 2022. 2 generic applications are approved; 2 of them carry a current (not discontinued) marketing status in Drugs@FDA; that status is not evidence that the generic is on sale.
FDA's NDC Directory lists nalmefene from 2 labelers under a generic (ANDA) application and from 2 brand labelers. A listing means the company has registered the product for sale; it does not show that every pharmacy stocks it. In the latest NADAC survey pharmacies bought only the brand, so a generic may not be on sale yet.
The Orange Book lists 2 patents for Opvee spray, the last expiring on August 4, 2042. A patent or exclusivity date is not the date a generic goes on sale: court cases and settlements move it either way.
- 1995 earliest approval on file
- 2022 first generic approved
- 2042 last listed patent
Source: Drugs@FDA, FDA NDC Directory and the Orange Book (openFDA bulk files, October 8, 2026)
What do pharmacies pay for nalmefene (Opvee)?
In CMS's NADAC survey of October 7, 2026, pharmacies paid $46.79 per unit (Opvee 2.7 mg nasal spray), about the same as a year earlier. The chart's scale runs from the lowest to the highest price shown, not from zero. NADAC is what retail pharmacies paid their wholesalers, per unit, in CMS's monthly survey; what a patient pays depends on insurance and the pharmacy.
- Opvee 2.7 mg nasal spray (brand)
| Strength and form | Brand or generic | Pharmacy cost | 30 tablets, or one pen or vial | 12-month change |
|---|---|---|---|---|
| Opvee 2.7 mg nasal spray | Brand | $46.79 per unit | n/a | no change |
Source: CMS National Average Drug Acquisition Cost (NADAC) survey, October 7, 2026: what retail pharmacies paid per unit; not a counter price
What does the nalmefene label say about other medicines?
The nalmefene label names 3 other medicines in its interaction, contraindication or warning sections. The labels of 27 other medicines name nalmefene. The sentences are the labels' own; a label lists what its studies and reports found, not every interaction.
| Medicine named | Section | What the label says |
|---|---|---|
| Buprenorphine | warnings and precautions | Reversal of respiratory depression by partial agonists or mixed agonist/antagonists such as buprenorphine and pentazocine, may be incomplete. |
| Methadone | warnings | Risk of Recurrent Respiratory Depression Accidental overdose with long acting opioids [such as methadone and levo -alpha- acetylmethadol (LAAM)] may result in prolonged respiratory depression. |
| Naloxone | warnings | While nalmefene hydrochloride injection has a longer duration of action than naloxone in fully reversing doses, the physician should be aware that a recurrence of respiratory depression is possible, even after an apparently adequate initial response to nalmefene hydrochloride injection treatment. |
Source: FDA drug label (nalmefene hydrochloride), Chengdu Shuode Pharmaceutical Co., Ltd, effective December 8, 2023 (SPL set 22d67228-6c24-47ca-afc7-52ef279520a0), via openFDA; the full label on DailyMed
What do FAERS reports show for nalmefene?
The FDA Adverse Event Reporting System holds 40 reports that list nalmefene among the medicines taken, through July 30, 2026, each a report of something that happened, not proof the medicine caused it; 8 are coded as a death and 16 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is.
The most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026
What next?
- Other opioid antagonists
- the pharmacologic class, with prices and generics
- Nalmefene side effects
- the label's list beside FAERS reports
- Check an interaction
- what two or more labels say about each other