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Opioid receptor modulator Pregnancy: There are no or limited data (fewer than 300 pregnancy outcomes) from the use of nalmefene in pregnant women, and animal studies have shown reproductive toxicity — Selincro is not recommended during pregnancy. Breast-feeding: available pharmacodynamic/toxicological data in animals have shown excretion of nalmefene/metabolites in milk; it is unknown whether nalmefene is excreted in human milk and a risk to newborns/infants cannot be excluded — a decision must be made whether to discontinue breast-feeding or to discontinue/abstain from Selincro therapy, taking into account the benefit of breast-feeding to the child and the benefit of therapy to the woman. Fertility: in fertility studies in rats, no effects were observed for nalmefene on fertility, mating, pregnancy or sperm parameters.

Nalmefene

Brand names: Selincro

Nalmefene is an opioid receptor modulator used to reduce alcohol consumption in adults with alcohol dependence.

Adult dose

Dose: Alcohol dependence — reduction of alcohol consumption, taken AS-NEEDED: one 18 mg film-coated tablet (Selincro is a single-strength product). On each day the patient perceives a risk of drinking alcohol, one tablet should be taken, preferably 1-2 hours prior to the anticipated time of drinking. If the patient has started drinking alcohol without taking Selincro, the patient should take one tablet as soon as possible. The maximum dose of Selincro is one tablet per day. INITIATION: at an initial visit the patient's clinical status, alcohol dependence and level of alcohol consumption should be evaluated; the patient is then asked to record his or her alcohol consumption for approximately two weeks, and at the next visit Selincro may be initiated in patients who continued to have a high drinking risk level (DRL) over this two-week period, in conjunction with psychosocial intervention focused on treatment adherence and reducing alcohol consumption.
Route: Oral (PO) — the film-coated tablet should be swallowed whole. It must not be divided or crushed, because nalmefene may cause skin sensitisation when in direct contact with the skin. Can be taken with or without food.
Frequency: As-needed — on each day a risk of drinking alcohol is perceived, preferably 1-2 hours before the anticipated time of drinking. Maximum one tablet per day.
Max: One 18 mg tablet per day — verbatim from the SPC posology: 'The maximum dose of Selincro is one tablet per day.'
The openFDA record still present in this bundle is a PARENTERAL opioid antagonist for reversal of postoperative opioid depression and management of known or suspected opioid overdose; it is a different product, route and indication, and NONE of its microgram/kg figures have been used here. TREATMENT REVIEW: during pivotal trials the greatest improvement was observed within the first 4 weeks; the patient's response to treatment and the need for continued pharmacotherapy should be evaluated on a regular (for example, monthly) basis. Clinical data for the use of Selincro under randomised controlled conditions are available for a period of 6 to 12 months, and caution is advised if Selincro is prescribed for more than 1 year. TREATMENT GOAL: Selincro is not for patients for whom the treatment goal is immediate abstinence — reduction of alcohol consumption is an intermediate goal on the way to abstinence. SPECIAL POPULATIONS: no dose adjustment is recommended for the elderly (65 years of age and over), or for mild or moderate renal impairment, or for mild or moderate hepatic impairment — but caution is advised in each of these groups (limited clinical data in patients 65 years and over; more frequent monitoring suggested in mild or moderate hepatic or renal impairment). Severe hepatic impairment and severe renal impairment (eGFR <30 ml/min per 1.73 m2) are contraindications, not dose reductions. OPIOIDS: Selincro should be temporarily discontinued for 1 week prior to the anticipated use of opioids, for example if opioid analgesics might be used during elective surgery; in an emergency the amount of opioid required may be greater than usual and must be titrated individually with close observation for respiratory depression. Some sections of the product information we used were incomplete — check the full SPC. The §4.1 indications section was not fetched, so the indication wording above is taken from the posology and warnings text itself.

Paediatric dose

Route: N/A
Frequency: N/A
Max: Not established
UK SPC §4.2 Paediatric population, verbatim: 'The safety and efficacy of Selincro in children and adolescents <18 years of age have not been established. No data are available.' No paediatric dose is published here and none may be derived from the adult tablet. Verify any off-label use under 18 years against a children's formulary and specialist advice.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients listed in section 6.1
  • Patients taking opioid agonists — such as opioid analgesics, opioids for substitution therapy with opioid agonists (e.g. methadone) or partial agonists (e.g. buprenorphine)
  • Patients with current or recent opioid addiction
  • Patients with acute symptoms of opioid withdrawal
  • Patients for whom recent use of opioids is suspected
  • Patients with severe hepatic impairment (Child-Pugh classification)
  • Patients with severe renal impairment (eGFR <30 ml/min per 1.73 m2)
  • Patients with a recent history of acute alcohol withdrawal syndrome, including hallucinations, seizures and delirium tremens

Side effects

  • Most common overall — nausea, dizziness, insomnia and headache; the majority mild or moderate, associated with treatment initiation, and of short duration
  • Very common — insomnia, dizziness, headache, nausea
  • Common — sleep disorder, confusional state, restlessness, decreased libido (including loss of libido), decreased appetite, somnolence, tremor, disturbance in attention, paraesthesia, hypoaesthesia, tachycardia, palpitations, vomiting, dry mouth, diarrhoea, hyperhidrosis, muscle spasms, fatigue, asthenia, malaise, feeling abnormal, weight decreased
  • Uncommon — hallucination (auditory, tactile, visual and somatic), dissociation
  • Not known — visual impairment (mostly transient), angioedema, urticaria, pruritus, rash, erythema, myalgia, priapism
  • Confusional state and, rarely, hallucinations and dissociation were reported in clinical studies; most were mild or moderate, associated with treatment initiation, and short-lasting (a few hours to a few days), resolving during continued treatment and not recurring on repeated administration — but they could represent alcoholic psychosis, alcohol withdrawal syndrome or comorbid psychiatric disease

Monitoring

  • Before starting: evaluate clinical status, alcohol dependence and level of alcohol consumption, then have the patient record alcohol consumption for approximately two weeks and only initiate if a high drinking risk level (DRL) persists
  • Regular (for example, monthly) review of response to treatment and the need for continued pharmacotherapy — assess progress in reducing alcohol consumption, overall functioning, treatment adherence and any potential side effects
  • Reassess if prescribing beyond 1 year — randomised controlled data extend only to 6 to 12 months
  • Monitor for psychiatric symptoms; if these are not associated with treatment initiation and/or are not transient, consider alternative causes and assess the need to continue. Increased suicidal risk in alcohol and substance abusers is not reduced by nalmefene
  • More frequent monitoring in mild or moderate hepatic or renal impairment; caution with elevated ALAT or ASAT (>3 times ULN), as such patients were excluded from the clinical development programme
  • If opioids must be given in an emergency, monitor closely for respiratory depression and other adverse reactions, and titrate the opioid dose individually

Clinical monograph

How it works

It modulates the brain reward system through antagonism at mu and delta opioid receptors and partial agonism at kappa opioid receptors, reducing the reinforcing effects of alcohol.

Prescribing in practice

  • Because it antagonises opioid receptors, nalmefene must not be used in patients taking opioids and can precipitate acute opioid withdrawal or block the effect of opioid analgesia.
  • It is intended to be taken as needed on days when there is a perceived risk of drinking, and should be combined with ongoing psychosocial support focused on reducing consumption.
  • It is not suitable for patients who require immediate alcohol detoxification or who have severe hepatic or renal impairment.

Monitoring

Monitor alcohol consumption, treatment adherence and continued need for therapy, alongside liver function where clinically indicated.

Counselling the patient

  • Take one tablet on days when you feel there is a risk you will drink, ideally before drinking.
  • Tell your healthcare team you take nalmefene if you ever need strong (opioid) painkillers.
  • This medicine works best alongside support aimed at cutting down your drinking.

Evidence & guidelines

NICE recommends nalmefene, together with psychosocial support, as an option for reducing alcohol consumption in certain adults with alcohol dependence.

Reference: NICE TA325; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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