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Opioid Receptor Modulator (Alcohol Dependence — 'As-Needed' Therapy) Pregnancy: Contraindicated — opioid receptor modulation may affect foetal opioid signalling (important in neonatal breathing and stress response). Effective contraception required.

Nalmefene

Brand names: Selincro

Adult dose

Dose: 18 mg taken as-needed — 1–2 hours before anticipated drinking. Maximum 1 tablet per day
Route: Oral
Frequency: As-needed (not daily — only on days patient anticipates drinking alcohol)
Max: 18 mg/day
Reduction of alcohol consumption in adults with alcohol dependence who have a high drinking risk level (>60 g/day men, >40 g/day women) and do not require immediate alcohol detoxification. Start with psychosocial support. Take 1–2 hours before drinking; if already started drinking, take as soon as possible. Do not take on days not planning to drink. Source: BNF 90; NICE TA325.

Paediatric dose

Dose: Not licensed under 18 years N/A/kg
Route: N/A
Frequency: N/A
Max: N/A
Not licensed for paediatric alcohol dependence.

Dose adjustments

Renal

Severe renal impairment: not recommended — nalmefene and metabolites accumulate. Mild-moderate: no dose adjustment.

Hepatic

Severe hepatic impairment (Child-Pugh C): not recommended — significantly increased exposure. Mild-moderate: no dose adjustment.

Paediatric weight-based calculator

Not licensed for paediatric alcohol dependence.

Clinical pearls

  • As-needed dosing — paradigm shift from daily abstinence: nalmefene is the first pharmacological treatment designed for harm reduction in alcohol dependence — reducing consumption rather than mandating complete abstinence. NICE TA325 approved for patients with high-risk drinking who do not require immediate detox and do not want to pursue complete abstinence. This is a significant cultural shift in addiction medicine.
  • ESENSE1 and ESENSE2 trials: nalmefene significantly reduced heavy drinking days and total alcohol consumption vs placebo over 6 months in patients who continued drinking. Efficacy was seen regardless of whether patients used the tablet before every drinking occasion or not.
  • Mechanism: nalmefene is a partial agonist at kappa opioid receptors and antagonist at mu and delta opioid receptors. Alcohol's reinforcing and euphoric effects are partly mediated via endogenous opioid system (endorphin release). Blocking mu/delta opioid receptors reduces alcohol-associated reward → reduces urge to drink. Different from naltrexone — nalmefene also acts on kappa receptors.
  • Must exclude opioid use before prescribing: carry out opioid use history and urine drug screen. If patient uses opioids (prescribed or illicit), nalmefene will precipitate acute withdrawal and block therapeutic opioids. Also warn patients: if they need surgery or develop acute pain while taking nalmefene, inform the anaesthetist and surgical team that opioid analgesics will be less effective.
  • Combine with psychosocial intervention: NICE TA325 specifies nalmefene should only be prescribed alongside motivational enhancement therapy or other psychosocial support — pharmacological treatment alone is insufficient for sustained alcohol reduction. Source: BNF 90; NICE TA325; Gual et al. Eur Neuropsychopharmacol 2013 (ESENSE1); Mann et al. Biol Psychiatry 2013 (ESENSE2).

Contraindications

  • Current opioid agonist therapy (methadone, buprenorphine — nalmefene precipitates acute withdrawal)
  • Recent use of opioid analgesics (within 7–10 days — acute opioid withdrawal risk)
  • Acute alcohol withdrawal requiring detoxification
  • Severe hepatic or renal impairment
  • Hypersensitivity to nalmefene or naltrexone (cross-reactivity possible)

Side effects

  • Nausea, dizziness, insomnia (most common — at onset; typically mild and transient; take with food to reduce GI side effects)
  • Vomiting, headache, decreased appetite
  • Sleep disturbances, vivid dreams (opioid receptor modulation affects sleep REM cycle)
  • Confusional state, dissociation (rare — usually mild)
  • Fatigue, malaise
  • Precipitated opioid withdrawal if opioids recently used (see contraindications)

Interactions

  • Opioid analgesics: nalmefene blocks opioid receptors — analgesics (morphine, codeine, tramadol, fentanyl) will be ineffective. If emergency analgesia needed, higher-than-usual opioid doses may be required and patient must be monitored for respiratory depression (opioid effect eventually overcomes blockade at supratherapeutic doses)
  • Opioid antidiarrhoeals (loperamide): reduced efficacy (opioid receptor blockade)
  • Alcohol: nalmefene is intended for concurrent use with alcohol (PRN dosing before drinking) — reduces the rewarding effects of alcohol by mu/delta opioid receptor antagonism

Monitoring

  • Alcohol consumption (alcohol diary or timeline follow-back; standardised units per week at each visit)
  • Liver function tests (baseline and 3-monthly — alcohol-associated hepatic damage monitoring; heavy alcohol use causes transaminase elevation)
  • Mental health assessment (depression, anxiety — comorbid with alcohol dependence)
  • Opioid use check (before each prescription renewal — exclude opioid use)
  • Physical health (BP, weight, nutritional status)

Reference: BNFc; BNF 90; NICE TA325 (nalmefene for alcohol dependence); Gual et al. Eur Neuropsychopharmacol 2013 (ESENSE1); Mann et al. Biol Psychiatry 2013 (ESENSE2); MHRA SPC Selincro. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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