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Nalmefene Hydrochloride

2 mg/2mL · Solution

  • Prescription only
  • Opioid Antagonist
Made by
Chengdu Shuode Pharmaceutical Co., Ltd

Quoted from the official source. Not yet reviewed by Mediclarum — the leaflet in your pack is authoritative.

At a glance

Quoted from the official label · 2023-12-08

What it is

Opioid Antagonist

Used for
  • Nalmefene Hydrochloride Injection is indicated for the complete or partial reversal of opioid drug effects, including respiratory depression, induced by either natural or synthetic opioids.
The label’s usual adult dose

Management of Known or Suspected Opioid Overdose Use 1.0 mg/mL dosage strength (green label).

Full directions ↓
Do not take it if

Nalmefene Hydrochloride Injection is contraindicated in patients with a known hypersensitivity to the product.

All warnings ↓
Good to know
  • Prescription only
  • FDA enforcement reports list no ongoing recall, and none from the last two years, for this product code · checked 2026-10-02
1other products contain Nalmefene Hydrochloride Injection — compare makers, forms and strengths

Every line above is selected, not written, from the official label. Nothing is reworded. DailyMed

What it is for

  • Nalmefene 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.

From the official label · 2023-12-08 · DailyMed

How it works

From this product’s own US prescribing label.

Nalmefene hydrochloride injection prevents or reverses the effects of opioids, including respiratory depression, sedation, and hypotension.

Pharmacodynamic studies have shown that nalmefene hydrochloride injection has a longer duration of action than naloxone at fully reversing doses.

Half-life34 min
Mostly cleared after≈ 2.8 hfive half-lives — our arithmetic
How the body breaks it down

Nalmefene is metabolized by the liver, primarily by glucuronide conjugation, and excreted in the urine.

Quoted from the prescribing label, sections “Mechanism of Action” and “Pharmacokinetics”. DailyMed · 2023-12-08

Do not take it if

Nalmefene Hydrochloride Injection is contraindicated in patients with a known hypersensitivity to the product.

Quoted from the official label, section “Contraindications”.

How to take it

These directions are for this exact strength and form. Another one is different.

  • Important Information - Dosage Forms Nalmefene Hydrochloride Injection is supplied in two concentrations that can be identified by their color coded container labels:
  • a concentration suitable for postoperative use (100 µg/mL) in a blue labeled vial containing ONE (1) mL and a concentration suitable for the management of overdose (1 mg/mL, 10 times as concentrated, 20 times as much drug) in a green labeled vial containing TWO (2) mL.
  • Proper steps should be taken to prevent use of the incorrect concentration.
  • General Principles Nalmefene hydrochloride injection should be titrated to reverse the undesired effects of opioids.
  • Once adequate reversal has been established, additional administration is not required and may actually be harmful due to unwanted reversal of analgesia or precipitated withdrawal.
  • Duration of Action The duration of action of nalmefene hydrochloride injection is as long as most opioid analgesics.
  • The apparent duration of action of nalmefene hydrochloride injection will vary, however, depending on the half-life and plasma concentration of the narcotic being reversed, the presence or absence of other drugs affecting the brain or muscles of respiration, and the dose of nalmefene hydrochloride injection administered.
  • Partially reversing doses of nalmefene hydrochloride injection (1 µg/kg) lose their effect as the drug is redistributed through the body, and the effects of these low doses may not last more than 30-60 minutes in the presence of persistent opioid effects.
  • Fully reversing doses (1 mg/70 kg) have been shown to last many hours in both experimental and clinical studies, but may complicate the management of patients who are in pain, at high cardiovascular risk, or who are physically dependent on opioids.
  • The recommended doses represent a compromise between a desirable controlled reversal and the need for prompt response and adequate duration of action.
  • Using higher dosages or shorter intervals between incremental doses is likely to increase the incidence and severity of symptoms related to acute withdrawal such as nausea, vomiting, elevated blood pressure, and anxiety.
  • Patients Tolerant to or Physically Dependent on Opioids Nalmefene hydrochloride injection may cause acute withdrawal symptoms in individuals who have some degree of tolerance to and dependence on opioids.
  • These patients should be closely observed for symptoms of withdrawal following administration of the initial and subsequent injections of nalmefene hydrochloride injection.
  • Subsequent doses should be administered with intervals of at least 2-5 minutes between doses to allow the full effect of each incremental dose of nalmefene hydrochloride injection to be reached.
  • Recommended Doses for Reversal of Postoperative Opioid Depression Use 100 µg/mL dosage strength (blue label) and see Table 2 for initial doses.
  • The goal of treatment with nalmefene hydrochloride injection in the postoperative setting is to achieve reversal of excessive opioid effects without inducing a complete reversal and acute pain.
  • This is best accomplished with an initial dose of 0.25 µg/kg followed by 0.25 µg/kg incremental doses at 2-5 minute intervals, stopping as soon as the desired degree of opioid reversal is obtained.
  • A cumulative total dose above 1.0 µg/kg does not provide additional therapeutic effect.
  • Table 2:
  • Reversal of Postoperative Opioid Depression Body Weight mL of Nalmefene 100 µg/mL Solution 50 kg 0.125 60 kg 0.150 70 kg 0.175 80 kg 0.200 90 kg 0.225 100 kg
  • 0.250 In cases where the patient is known to be at increased cardiovascular risk, it may be desirable to dilute Nalmefene Hydrochloride Injection 1:1 with saline or sterile water and use smaller initial and incremental doses of 0.1 µg/kg.
  • Management of Known or Suspected Opioid Overdose Use 1.0 mg/mL dosage strength (green label).
  • The recommended initial dose of nalmefene hydrochloride injection for non-opioid dependent patients is 0.5 mg/70 kg.
  • If needed, this may be followed by a second dose of 1.0 mg/70 kg, 2-5 minutes later.
  • If a total dose of 1.5 mg /70 kg has been administered without clinical response, additional Nalmefene Hydrochloride Injection is unlikely to have an effect.
  • Patients should not be given more nalmefene hydrochloride injection than is required to restore the respiratory rate to normal, thus minimizing the likelihood of cardiovascular stress and precipitated withdrawal syndrome.
  • If there is a reasonable suspicion of opioid dependency, a challenge dose of nalmefene hydrochloride injection 0.1 mg/70 kg should be administered initially.
  • If there is no evidence of withdrawal in 2 minutes, the recommended dosing should be followed.
  • Nalmefene hydrochloride injection had no effect in cases where opioids were not responsible for sedation and hypoventilation.
  • Therefore, patients should only be treated with Nalmefene Hydrochloride Injection when the likelihood of an opioid overdose is high, based on a history of opioid overdose or the clinical presentation of respiratory depression with concurrent pupillary constriction.
  • Repeated Dosing Nalmefene hydrochloride injection is the longest acting of the currently available parenteral opioid antagonists.
  • If recurrence of respiratory depression does occur, the dose should again be titrated to clinical effect using incremental doses to
  • avoid over-reversal.
  • Hepatic and Renal Disease Hepatic disease and renal failure substantially reduce the clearance of nalmefene (see Pharmacokinetic s ).
  • For single episodes of opioid antagonism, adjustment of nalmefene hydrochloride injection dosage is not required.
  • However, in patients with renal failure, the incremental doses should be delivered slowly (over 60 seconds) to minimize the hypertension and dizziness reported following the abrupt administration of nalmefene to such patients.
  • Loss of Intravenous Access Should intravenous access be lost or not readily obtainable, a pharmacokinetic study has shown that a single dose of nalmefene hydrochloride injection should be effective within 5-15 minutes after intramuscular or subcutaneous doses of 1.0 mg.
  • (see Pharmacokinetics .)

Quoted from the official label, section “Dosage & Administration”.

Other warnings

  • Use of Nalmefene Hydrochloride Injection in Emergencies Nalmefene Hydrochloride Injection, like all drugs in this class, is not the primary treatment for ventilatory failure.
  • In most emergency settings, treatment with Nalmefene Hydrochloride Injection should follow, not precede, the establishment of a patent airway, ventilatory assistance, administration of oxygen, and establishment of circulatory access.
  • 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.
  • Respiratory depression in both the postoperative and overdose setting may be complex and involve the effects of anesthetic agents, neuromuscular blockers, and other drugs.
  • 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.
  • Patients treated with Nalmefene Hydrochloride Injection should be observed until, in the opinion of the physician, there is no reasonable risk of recurrent respiratory depression.
  • General CARDIOVASCULAR RISKS WITH NARCOTIC ANTAGONISTS Pulmonary edema, cardiovascular instability, hypotension, hypertension, ventricular tachycardia, and ventricular fibrillation have been reported in connection with opioid reversal in both postoperative and emergency department settings.
  • In many cases, these effects appear to be the result of abrupt reversal of opioid effects.
  • Although nalmefene hydrochloride injection has been used safely in patients with pre-existing cardiac disease, all drugs of this class should be used with caution in patients at high cardiovascular risk or who have received potentially cardiotoxic drugs.
  • (See DOSAGE AND ADMINISTRATION .) RISK OF PRECIPITATED WITHDRAWAL Nalmefene hydrochloride injection, like other opioid antagonists, is known to produce acute withdrawal symptoms and, therefore, should be used with extreme caution in patients with known physical dependence on opioids or following surgery involving high doses of opioids.
  • Imprudent use or excessive doses of opioid antagonists in the postoperative setting has been associated with hypertension, tachycardia, and excessive mortality in patients at high risk for cardiovascular complications.
  • (See PRECAUTIONS .) INCOMPLETE REVERSAL OF BUPRENORPHINE Preclinical studies have shown that nalmefene at doses up to 10 mg/kg (437 times the maximum recommended human dose) produced incomplete reversal of buprenorphine- induced analgesia in animal models.
  • This appears to be a consequence of a high affinity and slow displacement of buprenorphine from the opioid receptors.
  • Hence, nalmefene hydrochloride injection may not completely reverse buprenorphine-induced respiratory depression.
  • Drug Interactions Nalmefene hydrochloride injection has been administered after benzodiazepines, inhalational anesthetics, muscle relaxants, and muscle relaxant antagonists administered in conjunction with general anesthesia.
  • It also has been administered in outpatient settings, both in trials in conscious sedation and in the emergency management of overdose following a wide variety of agents.
  • No deleterious interactions have been observed.
  • Preclinical studies have shown that both flumazenil and nalmefene can induce seizures in animals.
  • The coadministration of both flumazenil and nalmefene produced fewer seizures than expected in a study in rodents, based on the expected effects of each drug alone.
  • Based on these data, an adverse interaction from the coadministration of the two drugs is not expected, but physicians should remain aware of the potential risk of seizures from agents in these classes.
  • Carcinogenesis, Mutagenesis, Impairment of Fertility Nalmefene did not have mutagenic activity in the Ames test with five bacterial strains or the mouse lymphoma assay.
  • Clastogenic activity was not observed in the mouse micronucleus test or in the cytogenic bone marrow assay in rats.
  • However, nalmefene did exhibit a weak but significant clastogenic activity in the human lymphocyte metaphase assay in the absence but not in the presence of exogenous metabolic activation.
  • Oral administration of nalmefene up to 1200 mg/m 2 /day did not affect fertility, reproductive performance, and offspring survival in rats.
  • Use in Pregnancy Reproduction studies have been performed in rats (up to 1200 mg/m 2 /day) and rabbits (up to 2400 mg/m 2 /day) by oral administration of nalmefene and in rabbits by intravenous administration up to 96 mg/m 2 /day (114 times the human dose).
  • There was no evidence of impaired fertility or harm to the fetus.
  • There are, however, no adequate and well-controlled studies in pregnant women.
  • Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.
  • Nursing Mothers Nalmefene and its metabolites were secreted into rat milk, reaching concentrations approximately three times those in plasma at one hour and decreasing to about half the corresponding plasma concentrations by 24 hours following bolus administration.
  • As no clinical information is available, caution should be exercised when Nalmefene Hydrochloride Injection is administered to a nursing woman.
  • Use in Pediatric Patients Safety and effectiveness of nalmefene hydrochloride injection in pediatric patients have not been established.
  • Use in Neonates The safety and effectiveness of nalmefene hydrochloride injection in neonates have not been established in clinical studies.
  • In a preclinical study, nalmefene was administered by subcutaneous injection to rat pups at doses up to 205 mg/m 2 /day throughout maternal lactation without producing adverse effects.
  • A preclinical study evaluating the irritancy of the dosage form following arterial and venous administration in animals showed no vascular irritancy.
  • Nalmefene Hydrochloride Injection should only be used in the resuscitation of the newborn when, in the opinion of the treating physician, the expected benefits outweigh the risks.
  • Geriatric Use Clinical studies of nalmefene hydrochloride injection did not include sufficient number of subjects aged 65 and over to determine whether they respond differently from younger subjects.
  • Other reported clinical experience has not identified differences in responses between the elderly and younger patients.
  • In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

Quoted from the official label, section “Warnings”.

Pregnancy and breastfeeding

  • Special Populations ELDERLY Dose proportionality was observed in nalmefene AUC 0-inf following 0.5 to 2 mg intravenous administration to elderly male subjects.
  • Following a 1 mg intravenous nalmefene dose, there were no significant differences between young (19-32 years) and elderly (62-80 years) adult male subjects with respect to plasma clearance, steady-state volume of distribution, or half-life.
  • There was an apparent age-related decrease in the central volume of distribution (young:
  • 3.9 ±
  • 1.1 L/kg, elderly: 2.8 ±
  • 1.1 L/kg) that resulted in a greater initial nalmefene concentration in the elderly group.
  • While initial nalmefene plasma concentrations were transiently higher in the elderly, it would not be anticipated that this population would require dosing adjustment.
  • No clinical adverse events were noted in the elderly following the 1 mg intravenous nalmefene dose.
  • PATIENTS WITH HEPATIC IMPAIRMENT Subjects with hepatic disease, when compared to matched normal controls, had a 28.3% decrease in plasma clearance of nalmefene (0.56 ±
  • 0.21 L/hr/kg versus 0.78 ±
  • 0.24 L/hr/kg, respectively).
  • Elimination halflife increased from 10.2 ± 2.2 hours to 11.9 ± 2.0 hours in the hepatically impaired.
  • No dosage adjustment is recommended since nalmefene will be administered as an acute course of therapy.
  • PATIENTS WITH RENAL IMPAIRMENT There was a statistically significant 27% decrease in plasma clearance of nalmefene in the end-stage renal disease (ESRD) population during interdialysis (0.57 ±
  • 0.20 L/hr/kg) and a 25% decreased plasma clearance in the ESRD population during intradialysis (0.59 ±0.18 L/hr/kg) compared to normals (0.79 ±
  • 0.24 L/hr/kg).
  • The elimination half-life was prolonged in ESRD patients from 10.2 ± 2.2 hours in normals to 26.1 ± 9.9 hours.
  • (See DOSAGE AND ADMINISTRATION .) GENDER DIFFERENCES There has not been sufficient pharmacokinetic study to make a definitive statement as to whether the pharmacokinetics of nalmefene differs between the genders.

Quoted from the official label, section “OTC — Pregnancy or Breast Feeding”.

If you take too much

In an emergency, call your local emergency number or a poison control centre.

  • Intravenous doses of up to 24 mg of nalmefene, administered to healthy volunteers in the absence of opioid agonists, produced no serious adverse reactions, severe signs or symptoms, or clinically significant laboratory abnormalities.
  • As with all opioid antagonists, use in patients physically dependent on opioids can result in precipitated withdrawal reactions that may result in symptoms that require medical attention.
  • Treatment of such cases should be symptomatic and supportive.
  • Administration of large amounts of opioids to patients receiving opioid antagonists in an attempt to overcome a full blockade has resulted in adverse respiratory and circulatory reactions.

Quoted from the official label, section “Overdosage”.

Misuse and dependence

Nalmefene hydrochloride injection is an opioid antagonist with no agonist activity. It has no demonstrated abuse potential, is not addictive, and is not a controlled substance.

Quoted from the official label, section “Drug Abuse and Dependence”.

Side effects

  • Adverse event information was obtained following administration of nalmefene hydrochloride injection to 152 normal volunteers and in controlled clinical trials to 1127 patients for the treatment of opioid overdose or for postoperative opioid reversal.
  • Nalmefene was well tolerated and showed no serious toxicity during experimental administration to healthy individuals, even when given at 15 times the highest recommended dose.
  • In a small number of subjects, at doses exceeding the recommended nalmefene hydrochloride injection dose, nalmefene produced symptoms suggestive of reversal of endogenous opioids, such as have been reported for other narcotic antagonist drugs.
  • These symptoms (nausea, chills, myalgia, dysphoria, abdominal cramps, and joint pain) were usually transient and occurred at very low frequency.
  • Such symptoms of precipitated opioid withdrawal at the recommended clinical doses were seen in both postoperative and overdose patients who were later found to have had histories of covert opioid use.
  • Symptoms of precipitated withdrawal were similar to those seen with other opioid antagonists, were transient following the lower doses used in the postoperative setting, and more prolonged following the administration of the larger doses used in the treatment of overdose.
  • Tachycardia and nausea following the use of nalmefene in the postoperative setting were reported at the same frequencies as for naloxone at equivalent doses.
  • The risk of both these adverse events was low at doses giving partial opioid reversal and increased with increases in dose.
  • Thus, total doses larger than 1.0 µg/kg in the postoperative setting and 1.5 mg/70 kg in the treatment of overdose are not recommended.
  • Relative Frequencies of Common Adverse Reactions With an Incidence Greater than 1% (all patients, all clinical settings) Adverse Event Nalmefene Naloxone Placebo N=1127 N=369 N=77 Nausea 18% 18% 6% Vomiting 9% 7% 4% Tachycardia 5% 8% - Hypertension 5% 7% - Postoperative pain 4% 4% N/A Fever 3% 4% - Dizziness 3% 4% 1% Headache 1% 1% 4% Chills 1% 1% - Hypotension 1% 1% - Vasodilatation 1% 1% - Incidence less than 1% CARDIOVASCULAR:
  • Bradycardia, arrhythmia DIGESTIVE:
  • Diarrhea, dry mouth NERVOUS SYSTEM:
  • Somnolence, depression, agitation, nervousness, tremor, confusion, withdrawal syndrome, myoclonus RESPIRATORY:
  • Pharyngitis SKIN:
  • Pruritus UROGENITAL:
  • Urinary retention The incidence of adverse events was highest in patients who received more than the recommended dose of nalmefene hydrochloride injection.
  • Laboratory findings:
  • Transient increases in CPK were reported as adverse events in 0.5% of the postoperative patients studied.
  • These increases were believed to be related to surgery and not believed to be related to the administration of nalmefene hydrochloride injection.
  • Increases in AST were reported as adverse events in 0.3% of the patients receiving either nalmefene or naloxone.
  • The clinical significance of this finding is unknown.
  • No cases of hepatitis or hepatic injury due to either nalmefene or naloxone were observed in the clinical trials.

Quoted from the official label, section “Adverse Reactions”.

What it looks like and how it is packed

  • Nalmefene Hydrochloride Injection is available in the following presentations:
  • A single-dose vial containing 1 mL of 100 µg/mL nalmefene base (Blue Label) Box of 1 (NDC 82432-101-01) A single-dose vial containing 2 mL of 1 mg/mL nalmefene base (Green Label) Box of 1 (NDC 82432-102-02) Protect from light,
  • store at 20°C-25°C (68°F to 77°F). [see USP Controlled Room Temperature] Discard unused portion.
  • Manufacturer Chengdu Shuode Pharmaceutical Co., Ltd No. 9 Lekang Road, Shuangliu District Chengdu, Sichuan 610200 China (CHN) Revision date:
  • 06/27/2023

Quoted from the official label, section “How Supplied”.

What is in it

  • Nalmefene Hydrochloride Injection Rx only DESCRIPTION Nalmefene Hydrochloride Injection, an opioid antagonist, is a 6-methylene analogue of naltrexone. The chemical structure is shown below:
  • Molecular Formula:
  • C 21 H 25 NO 3
  • HCl
  • H 2 O Molecular Weight:
  • 393.91, CAS # 1228646-72-7 Chemical Name:
  • 17-(Cyclopropylmethyl)-4,5α-epoxy-6-methylenemorphinan-3,14-diol, hydrochloride salt, monohydrate Nalmefene hydrochloride is a white to almost 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 pK a of 7.6. Nalmefene Hydrochloride Injection is available as a sterile solution for intravenous, intramuscular, and subcutaneous administration in two concentrations, containing 100 µg or 1.0 mg of nalmefene free base per mL. The 100 µg/mL concentration contains 110.8 µg of nalmefene hydrochloride and the 1.0 mg/mL concentration contains 1.108 mg of nalmefene hydrochloride per mL. Both concentrations contain 9.0 mg of sodium chloride per mL and the pH is adjusted in the range of 3.3-3.5 with hydrochloric acid. Concentrations and dosages of Nalmefene Hydrochloride Injection are expressed as the free base equivalent of nalmefene. image description

Quoted from the official label, section “Description”.

Ingredients people check for

Lactose, gluten, dyes, sugars and other ingredients that matter with an allergy, intolerance or diet — as this product’s FDA label lists them.

The stored label for this product has no list of inactive ingredients. The list on the pack is the one to check.

Quoted from the FDA label. A label that does not name an ingredient is not a guarantee that the product is free of it, and formulations change. With an allergy, check the pack and ask a pharmacist.

Same active substance, strength and form in other countries

Matched on active substance, strength and kind of form only. This is not a statement that the products are equivalent or interchangeable: other ingredients, release and approved uses can differ — ask a pharmacist before swapping.

Medicine passport: one printable page to show a pharmacist abroad

European UnionNo exact match for this strength and form

Every strength and form (1)

Details

Made byChengdu Shuode Pharmaceutical Co., Ltd
Active substanceNalmefene Hydrochloride Injection
Used inPain, sleep, mood, epilepsy and the brain
Strength2 mg/2mL
FormSolution
RouteIntramuscular; Intravenous; Subcutaneous
Packs1 VIAL, GLASS in 1 CARTON / 2 mL in 1 VIAL, GLASS
NDC82432-102

Source: NDC Directory · 2026-09-13 · not reviewed by a clinician

Source: US Food and Drug Administration, NDC Directory. Reuse terms: US government work (FDA).

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Other strengths and forms

3 products are sold under this name. Grouped by form; a number on a strength means several companies make it.

Same active substance

These contain the same substance. That does not mean one can replace another — ask a pharmacist.

Nalmefene Hydrochloride.1 mg/mLPrescription onlySolution Chengdu Shuode Pharmaceutical Co., Ltd · Nalmefene Hydrochloride Injection

See every product with Nalmefene Hydrochloride Injection