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zurnai (autoinjector)

Zurnai (Autoinjector) (Nalmefene Hydrochloride) is an opioid antagonist used to treat Opioid-Related Disorders, Respiration Disorders, Drug Overdose.

Nalmefene Hydrochloride · by Knoa Pharma

Not yet rated· sourced from the FDA label
Rated against independent regulatory sources·Last updated June 7, 2026·How we rate
Verified againstopenFDANIH DailyMedRxClass

Key facts

Active ingredient
Nalmefene Hydrochloride
Form
Injectable
Strength
Nalmefene Hydrochloride EQ 1.5MG BASE/0.5ML (EQ 1.5MG BASE/0.5ML)
Type
Prescription (Rx)
Brand or generic
Brand-name
Manufacturer
Knoa Pharma
FDA application
NDA218590

What is Zurnai (Autoinjector)?

From the FDA label:ZURNAI™ (nalmefene injection) is a sterile, pre-filled, single-dose auto-injector designed to deliver a dose of 1.5 mg nalmefene (provided as nalmefene hydrochloride) in 0.5 mL. Nalmefene hydrochloride, an opioid antagonist, is a 6-methylene analogue of naltrexone. The molecular structure of nalmefene is presented below: Molecular Formula: C 21 H 25 NO 3 ∙HCl Molecular Weight: 375.9, CAS# 58895-64-0 Chemical Name: 17-(Cyclopropylmethyl)-4,5α-epoxy-6-methylenemorphinan-3,14-diol, hydrochloride salt Nalmefene is a white to off-white crystalline powder which is freely soluble in water up to 130 mg/mL and slightly soluble in chloroform up to 0.13 mg/mL, with a pKa of 7.63. Each ZURNAI auto-injector delivers 1.5 mg nalmefene (equivalent to 1.7 mg nalmefene hydrochloride) in 0.5 mL solution. The pH range is 3.5 to 4.5. The inactive ingredients in ZURNAI nalmefene injection include: hydrochloric acid to adjust pH; magnesium chloride, 4.7 mg; and water for injection. Chemical Structure

How to use

ZURNAI is for intramuscular and subcutaneous use only. ( 2.1 ) Seek emergency medical care immediately after use. ( 2.1 ) Administer ZURNAI to the outer thigh, through clothing if necessary. ( 2.1 ) Administer additional doses of ZURNAI using a new ZURNAI auto-injector for each dose. If the patient does not respond or responds and then relapses into respiratory depression, additional doses of ZURNAI may be given every 2 to 5 minutes until emergency medical assistance arrives. ( 2.2 ) See Full Prescribing Information and Instructions for Use for important information on how to safely administer ZURNAI. ( 2.1 ) Additional supportive and/or resuscitative measures may be helpful while awaiting emergency medical assistance. ( 2.2 ) 2.1 Important Administration Instructions All approved nalmefene products achieve plasma concentrations that have been shown to be efficacious in reversing the effects of opioid overdose. Comparing different products on a nominal mg-for-mg basis may be misleading. ZURNAI is for intramuscular and subcutaneous use only. The device is ready to use. No device assembly is required. Do not prime or test prior to administration. ZURNAI delivers its entire contents automatically, upon injection. Inject ZURNAI into the anterolateral aspect of the thigh. ZURNAI can be administered through clothing if necessary. Do not reuse ZURNAI. Each ZURNAI device contains a…

Side effects

The following serious adverse reactions are described elsewhere in the labeling: Recurrent Respiratory and Central Nervous System Depression [see Warnings and Precautions (5.1) ] Precipitation of Severe Opioid Withdrawal [see Warnings and Precautions (5.3) ] Most common adverse reactions (incidence > 5%) are feeling hot, nausea, headache, dizziness, chills, vomiting, allodynia, palpitations, tinnitus, ear discomfort, feeling abnormal, burning sensation, hot flush, and irritability. ( 6 ) To report Suspected Adverse Reactions, contact Knoa Pharma LLC at 1-888-726-7535 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trial Experience Adult Clinical Trial Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety of ZURNAI is supported by pharmacokinetic and pharmacodynamic studies of ZURNAI in healthy subjects in a normal state and under steady state opioid agonism. The following adverse reactions were observed. In a pharmacokinetic study (NAL1005) of 21 healthy adult volunteers exposed to one dose of ZURNAI the most common adverse reactions were: dizziness and headache. In a pharmacodynamic study (NAL1004) of 23 healthy adult volunteers…

Warnings

Important safety information

Risk of Recurrent Respiratory and CNS Depression : A recurrence of respiratory depression is possible, therefore, keep the patient under continued surveillance and administer repeat doses of ZURNAI using a new auto-injector with each dose while awaiting emergency medical assistance. ( 5.1 ) Risk of Limited Efficacy with Partial Agonists or Mixed Agonists/Antagonists : Reversal of respiratory depression by partial agonists or mixed agonist/antagonists such as buprenorphine and pentazocine, may be incomplete. Repeat doses may be required. ( 5.2 ) Precipitation of Severe Opioid Withdrawal : The use of ZURNAI in patients who are opioid dependent may precipitate opioid withdrawal. In neonates, opioid withdrawal may be life-threatening if not recognized and properly treated. Monitor for the development of opioid withdrawal. ( 5.3 ) Risk of Cardiovascular (CV) Effects : Abrupt postoperative reversal of opioid depression may result in adverse CV effects. These events have primarily occurred in patients who had preexisting CV disorders or received other drugs that may have similar adverse CV effects. Monitor these patients closely in an appropriate healthcare setting after use of nalmefene hydrochloride. ( 5.3 ) Risk of Opioid Overdose from Attempts to Overcome the Blockade : Attempts to overcome opioid withdrawal symptoms caused by opioid antagonists with high or repeated doses of exogenous opioids may lead to opioid intoxication and death. ( 5.4 ) 5.1 Risk of Recurrent Respiratory and Central Nervous System Depression Respiratory depression in the community overdose setting may be complex and involve the effects of multiple or unknown drugs, some of which may be long-acting opioids. While the duration of action of nalmefene is as long as most opioids, a recurrence of respiratory depression is possible, even after an apparently adequate initial response to ZURNAI treatment [see Clinical Pharmacology (12.3) ]. Therefore, it is necessary to seek emergency medical assistance immediately after administration of the first dose of ZURNAI and to keep the patient under continued surveillance. A second dose may be necessary if there is recurrence of symptoms of opioid overdose. Additional supportive and/or resuscitative measures may be helpful while awaiting emergency medical assistance [see Dosage and Administration (2.2) ]. 5.2 Risk of Limited Efficacy with Partial Agonists or Mixed Agonist/Antagonists Reversal of respiratory depression by partial agonists or mixed agonist/antagonists such as buprenorphine and pentazocine, may be incomplete. Repeat doses of ZURNAI may be required to antagonize buprenorphine because the latter has a long duration of action due to its slow rate of binding and subsequent slow dissociation from the opioid receptor [see Dosage and Administration (2.3) ]. Buprenorphine antagonism is characterized by a gradual onset of the reversal effects and a decreased duration of action of the normally prolonged respiratory depression. 5.3 Precipitation of Severe Opioid Withdrawal The use of ZURNAI in patients who are opioid dependent may precipitate opioid withdrawal characterized by the following signs and symptoms: body aches, diarrhea, tachycardia, fever, runny nose, sneezing, piloerection, sweating, yawning, nausea or vomiting, nervousness, restlessness or irritability, shivering or trembling, abdominal cramps, weakness, and increased blood pressure. Abrupt postoperative reversal of opioid depression after using ZURNAI may result in nausea, vomiting, sweating, tremulousness, tachycardia, hypotension, hypertension, seizures, ventricular tachycardia and fibrillation, pulmonary edema, and cardiac arrest. Death, coma, and encephalopathy have been reported as sequelae of these events. These events have primarily occurred in patients who had pre-existing cardiovascular disorders or received other drugs that may have similar adverse cardiovascular effects. After use of ZURNAI, monitor patients with pre-existing cardiac disease or patients who have received medications with potential adverse cardiovascular effects for hypotension, ventricular tachycardia or fibrillation, and pulmonary edema in an appropriate healthcare setting. It has been suggested that the pathogenesis of pulmonary edema associated with the use of nalmefene is similar to neurogenic pulmonary edema, i.e., a centrally mediated massive catecholamine response leading to a dramatic shift of blood volume into the pulmonary vascular bed resulting in increased hydrostatic pressures. ZURNAI is not indicated for use in patients less than 12 years of age. In neonates, opioid withdrawal may be life-threatening if not recognized and properly treated and may include the following signs and symptoms: convulsions, excessive crying, and hyperactive reflexes. Monitor the patient for the development of the signs and symptoms of opioid withdrawal. There may be clinical settings, particularly the postpartum period in neonates with known or suspected exposure to maternal opioid use, where it is preferable to avoid the abrupt precipitation of opioid withdrawal symptoms. In these settings, use an alternative, opioid antagonist product that can be titrated to effect and, where applicable, dosed according to weight [see Use in Specific Populations (8.4) ]. 5.4 Risk of Opioid Overdose from Attempts to Overcome the Blockade ZURNAI is unlikely to produce acute withdrawal symptoms in non-opioid dependent patients. The use of ZURNAI in patients who are opioid dependent may precipitate opioid withdrawal. Attempting to overcome opioid withdrawal symptoms caused by opioid antagonists with high or repeated doses of exogenous opioids could lead to opioid intoxication and death. Inform patients of the potential consequences of trying to overcome the opioid blockade. Get emergency medical assistance as soon as possible after use of ZURNAI regardless of withdrawal symptoms.

Who should not take Zurnai (Autoinjector)

ZURNAI is contraindicated in patients known to be hypersensitive to nalmefene hydrochloride or to any other ingredients in the product. Hypersensitivity to nalmefene hydrochloride or to any other ingredients in ZURNAI. ( 4 )

Drug class

How this class works, per Opioid Antagonists - StatPearls - NCBI Bookshelf.

May treat (source: NIH RxClass)

See how Zurnai (Autoinjector) ranks — best-rated opioid antagonist for:

Dosage forms

Injectable

The forms currently marketed in the U.S., per the FDA National Drug Code Directory.

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Frequently asked questions

What does Zurnai (Autoinjector) treat?
Zurnai (Autoinjector) (Nalmefene Hydrochloride) may be used to treat opioid-related disorders, respiration disorders, drug overdose, based on NIH RxClass drug-classification data (conditions a drug may treat — not a verbatim copy of the FDA-approved label). This is general reference, not medical advice.
How does Zurnai (Autoinjector) work?
Zurnai (Autoinjector) is a opioid antagonist. Opioid antagonists attach to the same brain and body receptors that opioids use, but without switching them on. By occupying those receptors, they block opioids from binding and can rapidly reverse an overdose or curb opioid cravings.
Is there a coupon or discount for Zurnai (Autoinjector)?
pharmaranks is an independent ratings site, not a pharmacy — we don't issue coupons or sell Zurnai (Autoinjector). To pay less, ask your prescriber or pharmacist whether a generic equivalent exists, check the manufacturer's copay/savings card and patient-assistance program, and compare a pharmacy discount card against your insurance copay. Prices vary by pharmacy, insurance, and location, so always confirm at the counter. This is general reference, not medical or financial advice.
Who makes Zurnai (Autoinjector)?
Zurnai (Autoinjector) is marketed by Knoa Pharma. You can see Knoa Pharma's full profile, rating, and other products on pharmaranks.
Is Zurnai (Autoinjector) a brand-name or generic drug?
Zurnai (Autoinjector) is a brand-name product with the active ingredient Nalmefene Hydrochloride.
Is Zurnai (Autoinjector) available over the counter?
No. Zurnai (Autoinjector) is a prescription (Rx) medication in the US — you need a prescription from a licensed clinician (in person or via telehealth); it isn't sold over the counter. For some conditions there are OTC alternatives — ask your pharmacist.
What forms does Zurnai (Autoinjector) come in?
Zurnai (Autoinjector) is currently marketed as injectable, per the FDA's National Drug Code Directory.
What class of drug is Zurnai (Autoinjector)?
Zurnai (Autoinjector) is classified as opioid antagonist, per the FDA's Established Pharmacologic Class.
Is Zurnai (Autoinjector) FDA-registered?
Zurnai (Autoinjector) is on record with the U.S. FDA under application number NDA218590. You can verify this on its official FDA label.
Is Zurnai (Autoinjector) safe?
There's no single safe-or-not verdict, and we don't yet have a composite recall-safety score for Zurnai (Autoinjector). Review its FDA-label side effects and warnings below, and always consult a licensed professional.
What are the side effects of Zurnai (Autoinjector)?
Zurnai (Autoinjector)'s side effects are taken directly from its FDA label. From the label: The following serious adverse reactions are described elsewhere in the labeling: Recurrent Respiratory and Central Nervous System Depression [see Warnings and Precautions (5.1) ] Precipitation of Severe Opioid Withdrawal [see Warnings and Precautions (5.3) ] Most common adverse reactions (incidence… Both common and serious reactions are documented in full on this page. This is general reference from the FDA, not medical advice — always consult a professional.

Clinical content sourced from the FDA label via openFDA (U.S. FDA). View the FDA label on DailyMed → Provided for general reference only — not medical advice. Always consult a licensed professional and the current prescribing information.

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