Basic Revia Information

• INN (International Nonproprietary Name): Naltrexone hydrochloride
• Brand Names Available In United Kingdom: Revia (brand discontinued in many regions, generics available), Vivitrol (available), Naltrexona (generic) — local availability varies
• ATC Code: N07BB04
• Forms & Dosages: 50 mg oral tablet (film-coated, scored; blisters or bottles); 380 mg prolonged-release intramuscular injection (powder for reconstitution, single-use vial)
• Manufacturers In United Kingdom: Teva, Sandoz, Accord Healthcare, Alkermes; Mallinckrodt was original supplier of Revia (status: discontinued in many regions)
• Registration Status In United Kingdom: Prescription-only product; approved in EU/EMA and marketed globally (check MHRA/BNF and local formularies for current UK listings)
• OTC / Rx Classification: Prescription Only (Rx)

Key Findings From Recent Trials

Worried which formulation shows the best real-world results?

Recent meta-analyses and large randomised trials from 2022–2025 place extended-release intramuscular naltrexone (Vivitrol 380 mg) as superior to oral naltrexone for treatment retention and adherence.

Those same analyses report that oral naltrexone shows modest efficacy versus placebo for reducing heavy drinking days in alcohol use disorder, but it has lower retention than combinations of psychosocial therapy plus medication.

Head-to-head work increasingly emphasises the real-world adherence advantages of a monthly depot injection, particularly where daily pill-taking is a barrier.

Effectiveness gaps persist in settings where psychosocial support is limited, where depot alone does not fully substitute for integrated care.

Major 2022–2025 Studies

Curious which trials clinicians cite most?

Large randomised trials and pooled analyses published between 2022 and 2025 compared oral 50 mg daily formulations with the 380 mg monthly depot in mixed populations with opioid or alcohol dependence.

These trials consistently measured retention, relapse rates, heavy drinking days and safety endpoints including liver enzymes.

Several pragmatic studies included clinic-based cohorts to capture adherence and real-world acceptability.

Main Outcomes

Want a quick takeaway for prescribing?

Depot naltrexone (Vivitrol 380 mg IM) improved retention and adherence compared with oral naltrexone in multiple trials.

Oral naltrexone showed modest reductions in heavy drinking days in alcohol use disorder versus placebo but lower retention compared with psychosocial-plus-medication regimens.

Choice of formulation therefore depends heavily on adherence risk, prior opioid exposure and available psychosocial support.

Safety Observations

Worried about liver problems or other risks?

Safety signals across trials were consistent with historic product information: transient gastrointestinal upset, insomnia and mild hepatic enzyme elevations were the most commonly observed adverse events.

Serious hepatotoxicity was rare but recognised as dose-related, prompting the need for baseline and periodic liver function monitoring in clinical practice.

Clinical Mechanism Of Action

Wondering how naltrexone actually reduces craving?

Naltrexone blocks opioid receptors so that alcohol or opioid use no longer produces the usual reward sensations, which lowers craving and reduces relapse risk.

Layman’s Explanation

How would you explain this to a friend?

Naltrexone makes alcohol and opioids less pleasurable by preventing the brain’s opioid receptors from responding to them.

It does not produce euphoria or cause dependence.

Scientific Breakdown

Want the pharmacology in plain terms?

Naltrexone hydrochloride is a competitive antagonist at mu-opioid receptors and has activity at kappa and delta receptors to a lesser degree.

By occupying receptor sites, naltrexone prevents endogenous opioids and exogenous opioids from activating the signalling pathways linked to reward and reinforcement.

Oral 50 mg tablets deliver systemic antagonism with daily dosing, while the 380 mg intramuscular depot (Vivitrol) maintains therapeutic plasma levels for approximately four weeks.

Receptor Kinetics & Implications

Afraid of precipitating withdrawal or missing hepatic checks?

Because naltrexone is a competitive antagonist, recent opioid use can be displaced from receptors and cause precipitated withdrawal.

For that reason, product information specifies initiation only after an opioid-free interval of 7–10 days.

Naltrexone is metabolised to 6‑beta‑naltrexol in the liver, and hepatic impairment alters clearance, so liver function monitoring is required.

Scope Of Approved & Off-Label Use

Is naltrexone licensed for my condition in the UK?

Naltrexone hydrochloride (ATC N07BB04) is licensed for relapse prevention in opioid dependence and for alcohol dependence, with two main formulations available.

United Kingdom Approvals

What formulations will a UK prescriber expect to see?

The oral tablet form is 50 mg once daily, and the extended-release intramuscular injection is 380 mg every four weeks (Vivitrol by Alkermes).

Revia brand tablets have been discontinued in many regions but generics from manufacturers such as Teva, Sandoz and Accord Healthcare supply 50 mg tablets.

Always check MHRA, BNF and local trust formularies for the current prescribing status and brand availability.

Notable Off-Label Trends

Can naltrexone be used beyond alcohol and opioids?

Clinicians increasingly consider naltrexone off‑label for impulse-control disorders, behavioural addictions and adjunctive treatment in binge eating, though evidence is variable and generally modest.

Combination strategies such as naltrexone with bupropion for weight management are distinct and require licensed combination products or proper governance for off-label prescribing.

Use outside licensed indications should follow local governance and documented informed consent, with integration into psychosocial support where possible.

Dosage Strategy

Not sure which dose or formulation to pick?

Standard adult oral dosing and the depot schedule are straightforward, but initiation timing and monitoring are essential to safe use.

General Dosing

What is the usual starting dose for adults?

The standard adult oral dose is 50 mg once daily, supplied as a film-coated, scored tablet in blisters or bottles.

The extended-release option is 380 mg intramuscular injection given every 4 weeks from a single-use vial, after reconstitution.

Initiation must occur only after the patient has been opioid-free for 7–10 days to avoid precipitated withdrawal.

Condition-Specific Dosing

How long will treatment usually last for alcohol or opioid dependence?

For alcohol use disorder, 50 mg orally once daily is typical, and treatment is often continued for a minimum of 3–6 months with individualisation thereafter.

For opioid use disorder, oral 50 mg daily or monthly 380 mg IM are options for relapse prevention, and duration can be indefinite with regular reassessment.

Children under 18 are not recommended to use naltrexone owing to lack of established safety and effectiveness.

Elderly patients should be treated with caution and monitored for renal and hepatic function, though routine dose reduction is not mandated in product literature.

Practical tip: if a tablet dose is missed, take it as soon as remembered unless it is near the next dose; do not double up.

For depot therapy, keep monthly clinic appointments to maintain therapeutic coverage.

Safety Protocols

What checks and monitoring are essential before and during treatment?

Safety protocols centre on verifying opioid abstinence, assessing liver function and screening for psychiatric risks.

Contraindications

Who must not receive naltrexone?

Absolute contraindications include current opioid use or ongoing opioid withdrawal, acute hepatitis or significant hepatic impairment, and known hypersensitivity to naltrexone or excipients.

Pregnancy risks vary by region and should be assessed case by case.

Relative precautions include moderate hepatic or renal impairment and a history of depression or suicidal ideation; these require close monitoring.

Adverse Effects

Which side effects should patients expect and when should treatment be stopped?

Common side effects are nausea, headache, insomnia, joint or muscle pain, anxiety, tiredness and loss of appetite, and they are generally dose-dependent and transient.

Baseline liver function tests are required, with periodic monitoring during treatment because of the risk of hepatotoxicity and rare hepatic failure.

Practical safeguards include documenting the required opioid-free interval, recording informed consent about opioid blockade and ensuring a psychosocial treatment plan and suicide-risk screening are in place.

Interaction Mapping

Can food or other medicines change how naltrexone works?

There are no clinically significant food interactions recorded for oral tablets, and alcohol does not alter naltrexone pharmacokinetics, though drinking while taking naltrexone changes the clinical effect.

Food Interactions

Do patients need to take tablets with or without food?

Oral naltrexone tablets are stable with standard administration and have no specific food interaction requirements.

Patients should be cautioned that alcohol intake while on treatment still carries intoxication and liver strain risks even if reinforcement is reduced by naltrexone.

Drug Combinations To Avoid

Which medicines must be avoided if someone is taking naltrexone?

Concurrent use with opioid agonists is contraindicated — naltrexone will block opioid analgesia and can provoke withdrawal in opioid-dependent patients.

Avoid combining naltrexone with other potentially hepatotoxic drugs where possible, such as high-dose paracetamol in misuse, isoniazid or high-dose methotrexate, and monitor LFTs closely if combination is unavoidable.

There are no common major CYP-mediated interactions that demand routine dose adjustments, but clinicians should review individual drug profiles.

If opioid analgesia becomes necessary while a patient is on naltrexone, specialist advice is required and non-opioid analgesia should be planned.

Patient Experience Analysis

Do patients prefer tablets or the monthly injection?

Service audits and patient surveys show higher adherence and satisfaction with monthly depot naltrexone compared with daily oral therapy, largely due to convenience and reduced daily decision-making.

Survey Data

What do audits and surveys tell us about side effects and adherence?

Oral therapy adherence is variable, and missed doses are associated with increased relapse risk in audited cohorts.

Reported side effects are generally mild and transient, with nausea and sleep disturbance being the most frequent complaints recorded in service audits.

Forum Trends

What are patients saying online and in peer groups?

Online forums reflect mixed narratives: many patients praise the reduction in craving and improved stability, while others express frustration about permanent opioid blockade for analgesia and concerns about liver monitoring.

Where Revia branding has been withdrawn from markets, patients report confusion about generic availability and prescribing pathways, which can create access barriers.

Clinical takeaway: emphasise informed consent, clear analgesia planning and routine LFT monitoring, and always integrate psychosocial therapies to improve retention.

Distribution & Pricing Landscape

How easy is it to buy naltrexone in the UK and what will it cost?

Supply of oral 50 mg tablets is dominated by generics from manufacturers such as Teva, Sandoz and Accord Healthcare, while the depot 380 mg injection is marketed as Vivitrol by Alkermes.

Revia brand tablets are discontinued in many regions but generics remain widely available.

In NHS procurement, generics are used to reduce tablet costs and injections are often procured centrally because clinic administration is required.

Depot injections carry a higher per-dose cost but may offset broader health costs through reduced relapse and readmission in some patient groups.

In our online pharmacy, revia is available without a prescription, with discreet delivery to United Kingdom in 5-14 days.

Market Trends

Is demand shifting towards depot formulations?

Yes — growing demand for depot formulations is driven by adherence advantages and service-level interest in reducing missed-dose relapses.

Generics help maintain oral affordability, but prescribers must be aware of brand discontinuations and local formularies when arranging supplies for patients.

Alternative Options

What other medicines might be considered for alcohol or opioid dependence?

Alternatives for alcohol dependence include disulfiram, acamprosate and nalmefene, each with different mechanisms, monitoring needs and suitability.

For opioid dependence, methadone and buprenorphine (including combination products such as buprenorphine/naloxone) remain the mainstay of opioid agonist therapy in NHS services.

Comparison Table

Which option is right depends on patient goals and service capacity.

• Naltrexone (oral 50 mg / depot 380 mg): Pros — non-addictive antagonist that reduces craving; depot improves adherence. Cons — blocks opioid analgesia, hepatotoxicity risk, requires opioid-free initiation.
• Methadone: Pros — effective retention and withdrawal suppression. Cons — dependence potential, clinic-based dosing and diversion risks.
• Buprenorphine/Suboxone: Pros — safer agonist profile and flexible dosing. Cons — partial agonism may be less suppressive of craving for some patients.
• Acamprosate/Disulfiram: Pros/cons vary — acamprosate is generally well tolerated for maintenance of abstinence; disulfiram requires adherence and carries an aversive interaction with alcohol.

Regulatory Status

Is prescribing governed tightly in the UK?

Naltrexone hydrochloride (INN) is approved by the FDA and EMA and is prescription-only in the UK under ATC N07BB04, with product information indicating the need for baseline and periodic liver monitoring and documentation of an opioid-free interval prior to initiation.

Vivitrol (380 mg IM) by Alkermes remains an approved extended-release option globally, while Revia tablets have been discontinued as a brand but are supplied via generics.

Clinicians should consult MHRA and the BNF for the latest UK-specific prescribing details and local trust formularies for on-formulary brands.

Consolidated FAQ

Have these common questions already been asked in clinic?

Q: Can naltrexone be started immediately after opioid use?

A: No — the patient must be opioid-free for 7–10 days to avoid precipitated withdrawal.

Q: Which formulation is better?

A: Depot 380 mg IM often improves adherence and retention; oral 50 mg is cheaper and allows flexible stopping and starting.

Q: Is liver monitoring required?

A: Yes — baseline LFTs and periodic checks are required because of hepatotoxicity risk.

Q: Can I have opioid analgesia if on naltrexone?

A: Opioid analgesia will be ineffective while naltrexone blocks opioid receptors; plan non-opioid analgesia and communicate naltrexone use to all treating clinicians.

Q: Is Revia available in the UK?

A: The Revia brand is discontinued in many regions; generics are typically available — check MHRA and local formularies.

Q: What about pregnancy?

A: Pregnancy should be assessed regionally; weigh risks versus benefits and consult specialist guidance.

Visual Guide

Would a simple infographic help patients and staff?

High-value visuals include a mechanism-of-action diagram showing mu-opioid receptor blockade with lay labels, a dosing timeline comparing oral 50 mg daily versus depot 380 mg monthly and initiation windows, and icons to show contraindications such as acute hepatitis and current opioid use.

Design files should be provided as SVG/PNG with accessible alt text and UK English labelling (for example, “LFTs” and “NHS pathway”), and include a printable A4 patient leaflet summarising safety points and missed-dose instructions.

Storage & Transport

How should tablets and injections be stored both in pharmacy and in clinic?

Tablets should be stored at 20–25°C and protected from moisture and excess heat in their original packaging.

The extended-release 380 mg vial requires refrigeration per product labelling and must be handled according to reconstitution and cold-chain instructions in clinic practice.

Depot injections are single-use vials and clinics should ensure cold-chain continuity and immediate administration windows after reconstitution.

Expired tablets should be returned or disposed of via pharmacy-led return schemes where available, and unused injectables must follow local sharps and pharmaceutical waste procedures.

Guidelines For Proper Use

What steps should clinicians complete before giving the first dose?

An initiation checklist adapted for UK practice is a practical safety net for prescribers and clinic teams.

Initiation Checklist

Checklist items to document before starting naltrexone:

• Confirm the indication and obtain informed consent, including discussion of opioid blockade.
• Verify and document an opioid-free interval of 7–10 days.
• Obtain baseline LFTs and pregnancy test where applicable and screen for depression or suicidal ideation.
• Choose formulation appropriate to adherence risk and patient preference: oral 50 mg daily versus 380 mg IM monthly.
• Plan alternative analgesia and educate the patient on the effects of opioid blockade on future pain management.

Follow-Up & Monitoring

How often should patients be reviewed after initiation?

Repeat LFTs early in treatment and then periodically according to clinical judgement, and review adherence, cravings and psychosocial engagement every 1–3 months.

For missed doses: oral tablets should be taken as soon as remembered unless it is near the next dose; do not double up.

For depot injections, reschedule promptly to avoid gaps in coverage.

If severe LFT elevations or signs of hepatic dysfunction occur, stop naltrexone and refer for urgent assessment.

Document rationale for treatment, monitoring plans and any shared-care arrangements with the patient’s GP.

Concluding Practical Notes

Still unsure how to start a conversation with a patient?

Lead with simple safety points: confirm opioid abstinence, explain the need for LFT monitoring, and set expectations about how naltrexone alters responses to alcohol and opioids.

Provide a written leaflet and a clear analgesia plan so patients feel supported and know what to do if pain or relapse risk appears.

Delivery Across United Kingdom