This page shows what was measured, who it was measured in, and what that does not settle.
What Naltrexone does in the body
Used for alcohol use disorder and to prevent return to opioid use.
Alcohol and opioids both end up releasing the body's own opioid-like chemicals, which is a large part of why they feel rewarding. Naltrexone sits in the same receptors those chemicals use and does nothing there — it just occupies the seat. Drinking still happens, but it delivers less of a payoff, and taking an opioid on top of naltrexone produces no effect at all.
What happened in people
For alcohol problems, adding naltrexone reduced the chance of a heavy-drinking day by about one quarter.
✓ Reviewed first-read answer
Where this came from
A person wrote this and a reviewer approved it against this exact record. It carries no effect size.
A reviewer approved this against this record. The reviewed-claim record carrying the exact population and effect size does not exist yet.
No source is stored against this line.
The limit that matters most
For opioid problems, a person must first stop opioids long enough to avoid sudden severe withdrawal.
Where it acts
Mu-opioid receptors in ventral tegmental area, nucleus accumbens and brainstem
Kind of result
The kind of result is not recorded
Supervision
RNAWiki has not recorded a supervision or regulatory status for this substance.
What the registries record it as
Its recorded molecular formula is C20H23NO4, weighing 341.41.
US prescribing information · cd11c435-b0f0-4bb9-ae78-60f101f3703f · read 2026-08-30
Where each sentence above came from
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
The limit a reviewer approved as the one that matters most here.
The four opening statements run to 93 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Stand-in result
A stand-in result is a number measured because the real result takes too long.
A picture of it, and where the picture fails
It is like judging a journey by the speedometer rather than by arriving.
Where that stops being true. Speed does predict arrival. Many stand-in results do not predict the real one.
What people get wrong. A stand-in result is often reported as the result itself.
A surrogate endpoint substituted for a clinical endpoint, valid only where the substitution has been shown to hold.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
Pathway
A pathway is a chain of steps inside a cell, each one setting off the next.
A picture of it, and where the picture fails
A pathway is like a row of dominoes.
Where that stops being true. Dominoes fall one way. Pathways loop back and can switch themselves off.
What people get wrong. Changing one step is read as changing the outcome. Other steps often absorb it.
An ordered series of molecular interactions producing a defined cellular change.
What happened in people◇Read from sources, not yet reviewed
What was measured, goal by goal
One row for each goal a registered study measured something for. One column for each kind of thing that could be measured.
Registered studies list 40 outcome measures that RNAWiki could read. A registered study says what someone planned to measure. It does not say what they found. 0 of the matched studies tested this substance, and 0 posted a result.
There is no single score. A strong test result and a weak life result are different facts.
Goals down the side, kinds of measurement across the top. Each cell says what kind of thing was registered, not what was found.
Goal
Life outcome
What a body can do
How a person feels
A test result
A step in the body
Harms
How long
Who was studied
Mood
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
…Waiting for a reviewer2 registered symptom measure.
∅Nothing in the sources checkedNo registered study lists a test result for this goal.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Body weight
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
∅Nothing in the sources checkedNo registered study lists a symptom measure for this goal.
△Only a number moved2 registered test measure.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Energy
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
∅Nothing in the sources checkedNo registered study lists a symptom measure for this goal.
∅Nothing in the sources checkedNo registered study lists a test result for this goal.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Which registered measures put each goal on this table
Mood
depression; anxiety; hamilton depression rating scale
Body weight
weight gain; body weight from baseline
Energy
resting energy expenditure at low temperature
Sorted by fixed word lists, version v1. A name the rules do not recognise stays unsorted rather than moving to the nearest column.
What each mark on this table means
∅ Nothing in the sources checked
No registered study lists a life outcome for this goal.
… Waiting for a reviewer
2 registered symptom measure.
— Not recorded
Harms were not a registered measure for this goal.
△ Only a number moved
2 registered test measure.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
Percent days abstinent and time to first heavy drinking day over 16 weeks
✓ The study showed what it set out to show
Who was studied
COMBINE (NCT00006206)
How many people
1383
Study design
Phase 3
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Hazard ratio 0.72 for a heavy drinking day (97.5% CI 0.53 to 0.98, P = .02); naltrexone-by-behavioural-intervention interaction P = .009
Repeated elsewhere
Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. Acamprosate showed no significant effect in any combination, which was not the pre-trial expectation.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet daily, or extended-release intramuscular injection monthly
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 4 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What happened in people◇Read from sources, not yet reviewed
How close this is to real life
The top step is something a person would feel or care about. The bottom is a guess from software. Filled steps are where evidence exists for this substance.
■Living longer, or avoiding a major eventEvidence recorded. Death, a heart attack, a stroke, a hospital stay.1 registered measure of this kind. No reviewed result.
□What a body can do day to dayNo evidence recorded. Walking, dressing, breathing, recovering.No registered study measures this.
□Measured performanceNo evidence recorded. How much was lifted, how far was run, how fast.No registered study measures this.
■Symptoms and quality of lifeEvidence recorded. Pain, tiredness, mood, sleep, as the person rated it.3 registered measures of this kind.
■A number that stands in for healthEvidence recorded. Cholesterol, blood sugar, bone density. A stand-in, not the thing itself.7 registered measures of this kind.
■A step measured inside a personEvidence recorded. Something measured in human tissue or human cells.1 registered measure inside human tissue.
■AnimalsEvidence recorded. Mice, rats, dogs. Useful for ideas, not proof about people.Stored records in C. elegans (roundworm), Mouse, Rat, Dog. A result in animals says what to test next. It does not say what happens in people.
■Cells in a dishEvidence recorded. Cells or chemistry on a bench, far from a whole body.Stored mechanism abstracts describe steps measured in cells or tissue.
□A guess from softwareNo evidence recorded. Nobody measured it. RNAWiki never publishes one as a finding.RNAWiki stores no prediction for this record. Software can suggest a link. RNAWiki does not publish one as a finding.
Higher on these steps means closer to something a person would feel. It does not mean better done.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Start
Naltrexone
What a person takes: Oral tablet daily, or extended-release intramuscular injection monthly.
The measurement behind this step
The 50 mg oral tablet is taken daily; the extended-release injectable suspension delivers 380 mg into the gluteal muscle every four weeks from a polylactide-co-glycolide microsphere depot. The injectable removes the daily adherence question and replaces it with a monthly clinic visit.
Getting in
Swallowed daily, or injected monthly
Two very different products: a daily tablet, and a monthly injection into muscle that releases slowly from a polymer.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Oral naltrexone undergoes extensive first-pass metabolism to 6-beta-naltrexol, which is itself an antagonist and circulates at higher concentrations than the parent. The extended-release injectable suspends naltrexone in a polylactide-co-glycolide microsphere matrix for once-monthly intramuscular administration, bypassing first pass entirely.
Distributes to opioid receptors throughout the brain
It reaches the reward circuits and the brainstem, where the body's own opioid signals normally act.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Crosses the blood-brain barrier and occupies mu-opioid receptors in the ventral tegmental area, nucleus accumbens and brainstem. Receptor occupancy after a monthly injection remains high for weeks, which is what gives the depot formulation its dosing interval.
It fits the lock but does not turn it, and while it is there nothing else can get in.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Competitive antagonism at mu-opioid receptors with lower-affinity kappa and delta antagonism. No intrinsic activity: naltrexone produces no euphoria, no analgesia and no respiratory depression, and stopping it produces no withdrawal.
Alcohol releases the body's own opioid-like chemicals, which is part of why a first drink leads to a second. With the receptors occupied, that chain is weakened.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Alcohol consumption triggers endogenous beta-endorphin release that disinhibits ventral tegmental dopamine neurons. Mu-receptor blockade attenuates that alcohol-induced dopamine response, which is the pharmacological basis for the reduction in heavy drinking days rather than in drinking at all.
Fewer heavy drinking days, or complete opioid blockade
In alcohol use disorder the measurable result is fewer heavy drinking days, not abstinence. In opioid use disorder it is that an opioid dose has no effect.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Measured endpoints are percent days abstinent, hazard of a heavy drinking day, and confirmed opioid-negative urine. The clinical constraint that dominates practice is that a patient must be fully withdrawn before the first dose, because antagonism in a physically dependent patient precipitates severe withdrawal.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 5 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What it would be like to take◇Read from sources, not yet reviewed
Felt, measured, or meaningful
Three different things that get called the same word. Registered studies measured all three, and mixing them is how a blood test becomes a health claim.
Felt
Things a person could notice without a test.
anxiety
hamilton depression rating scale
adult investigator symptom rating scale
Measured
Things only a test, a scale or a device shows.
weight gain
urine toxicology for cocaine
urine toxicology
opiate use measured by urine toxicology results
body weight from baseline
ma urine samples
cerebral blood flow
time to reach the maximum drug concentration in plasma
Meaningful
Things that change how a life goes, not only a number.
time to relapse
A registered study says what someone planned to measure. It does not say what they found. A number moving is not the same as a life going better. The two are shown apart here.
Felt, but not shown to help. A person notices a change. No study showed it leads anywhere good.
Measured, but not felt. A number moves. The person notices nothing. Both can be true.
Measured, but not shown to matter. A number moves in the good direction. Nobody showed that lives went better.
Matters, but takes years. The result that counts may take longer than anyone would keep watching.
Names that fit none of the three (28)
days abstinent
retention
cocaine use
depression
addiction severity
global improvement
alcohol use
heavy drinking days
time to lapse
drinks per drinking day
retention in treatment
smoking cessation
prevalence abstinence
obsessive compulsive drinking scale
clinician administered ptsd scale
side effects
disease response
treatment retention
subjective marijuana effects
latency to initiate ad lib smoking session
These are harms, study-process measures, or names the rules did not recognise. They are shown rather than dropped.
What it would be like to take◇Read from sources, not yet reviewed
How long anything takes
Nine different lengths of time that get confused with each other. None of them is worked out from another.
Before anything is noticed.RNAWiki does not store this separately, and never works it out from another figure on this page.
Before a test result moves.RNAWiki does not store this separately, and never works it out from another figure on this page.
Before performance moves.RNAWiki does not store this separately, and never works it out from another figure on this page.
How long the result was watched.No finished study window is recorded for a study that tested this substance.
How long people took it.How long people actually took it is not stored. The study window is not the same thing.
How long people were followed.Follow-up length is not stored separately. It is never read off the study window, which would be a different thing.
How fast the body clears it. 4 hours hours
Read from the label, which states: “The mean elimination half-life (T 1/2 ) values for naltrexone and 6-β-naltrexol are 4 hours and 13 hours, respectively.”
How long effects linger.RNAWiki does not store this separately, and never works it out from another figure on this page.
Beyond the studies. Nothing is recorded about the long term.
The longest finished study sets the edge of what anyone measured.
A study window is not how long people took it, and neither is how long they were followed. Where RNAWiki holds only one of the three, it shows one.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
Adults with alcohol use disorder, and adults with opioid use disorder who have already completed withdrawal. Naltrexone must not be started in anyone with opioids on board — it will precipitate severe withdrawal.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What the label states about particular groups
On pediatric, the label states: “The safety and efficacy of VIVITROL have not been established in the pediatric population.”
US prescribing information · cd11c435-b0f0-4bb9-ae78-60f101f3703f · read 2026-08-30
On older people, the label states: “Clinical studies of VIVITROL did not include sufficient numbers of subjects age 65 and over to determine whether they respond differently from younger subjects.”
US prescribing information · cd11c435-b0f0-4bb9-ae78-60f101f3703f · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary The available data from published case series with VIVITROL use in pregnant women are insufficient to identify a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes.”
US prescribing information · cd11c435-b0f0-4bb9-ae78-60f101f3703f · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary Naltrexone and its major metabolite, 6β-naltrexol, are present in human milk.”
US prescribing information · cd11c435-b0f0-4bb9-ae78-60f101f3703f · read 2026-08-30
On people with reduced liver function, the label states: “The pharmacokinetics of VIVITROL are not altered in subjects with mild to moderate hepatic impairment (Groups A and B of the Child-Pugh classification).”
US prescribing information · cd11c435-b0f0-4bb9-ae78-60f101f3703f · read 2026-08-30
On people with reduced kidney function, the label states: “Pharmacokinetics of VIVITROL are not altered in subjects with mild renal insufficiency (creatinine clearance of 50-80 mL/min).”
US prescribing information · cd11c435-b0f0-4bb9-ae78-60f101f3703f · read 2026-08-30
Where the result stopped carrying
X:BOT intention-to-treat result, driven almost entirely by patients who never completed induction
Low-dose naltrexone in fibromyalgia: no separation from placebo on the primary pain endpoint
Acamprosate, tested alongside naltrexone in COMBINE, showed no effect at all in that trial despite positive European evidence
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to take◇Read from sources, not yet reviewed
Why it might seem to do nothing
A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.
It was studied for a different goal
The studies measured something else entirely.
On this record: Some registered studies measured things that match no goal on this page.
It was studied in different people
The people in the studies were not much like the reader.
On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
There was nothing to correct
Where a level is already normal, topping it up may change nothing.
On this record: The requirement for complete detoxification before the first dose is the practical barrier that X:BOT quantified: nearly three in ten patients assigned to it never started
The evidence may simply be wrong
Small early studies often do not hold up.
On this record: RNAWiki has not yet published a reviewed conclusion for this use.
Other reasons RNAWiki checked and found nothing for (9)
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
The product may not be what it says
Contents of a sold product are not always what the label states. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.
None of these is a reason to take more. Taking more is not a step this page ever suggests.
What it would be like to take◇Read from sources, not yet reviewed
What taking it involves
The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.
How it is supplied
Given by a clinician
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Oral tablet daily, or extended-release intramuscular injection monthly
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
RNAWiki has not recorded a supervision or regulatory status for this substance.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
No register row and no identity class settled the question.
No source is stored against this line.
What is in the pack
The 50 mg oral tablet is taken daily; the extended-release injectable suspension delivers 380 mg into the gluteal muscle every four weeks from a polylactide-co-glycolide microsphere depot. The injectable removes the daily adherence question and replaces it with a monthly clinic visit.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold and what that means for what is in the pack.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
A boxed warning for hepatotoxicity was removed from the US labelling in 2013 after the accumulated evidence did not support it; hepatic monitoring precautions remain. Naltrexone will precipitate severe opioid withdrawal in a physically dependent patient, so complete detoxification is required first. Opioid tolerance falls during treatment, so overdose risk is elevated if opioid use resumes after stopping. The injectable carries a risk of injection-site reactions including necrosis.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
These are reports people sent to a regulator. They do not show the medicine caused the reaction.
Nobody counted how many people took the medicine and reported nothing.
The same event can be reported more than once, and many reports are incomplete.
News coverage, lawsuits and new warnings change how often people report.
A count is not a rate and not a risk.
Naltrexone appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 1054 reaction mentions were counted. One report can name several reactions.
The recorded terms (10)
nausea — 298 reaction mentions
dizziness — 146 reaction mentions
headache — 135 reaction mentions
vomiting — 114 reaction mentions
feeling abnormal — 110 reaction mentions
insomnia — 60 reaction mentions
constipation — 57 reaction mentions
anxiety — 52 reaction mentions
hyperhidrosis — 43 reaction mentions
somnolence — 39 reaction mentions
open-targets-adr · recorded 2026-06-24 · a recorded source, not a stored snapshot
Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.
Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What is missing or unclear◇Read from sources, not yet reviewed
Does the exact form matter?
Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.
The form that was studied
Oral tablet daily, or extended-release intramuscular injection monthly
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
The injectable removes the daily adherence question and replaces it with a monthly clinic visit.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on which forms are sold and how they compare.
No source is stored against this line.
What is recorded as being sold
115 products list this as an active ingredient in the United States drug directory. 114 of them contain it and nothing else.
FDA National Drug Code directory · 72162-1566 · read 2026-08-29
They are sold as injection, suspension, powder, tablet, extended release and tablet, film coated, taken oral.
FDA National Drug Code directory · 72162-1566 · read 2026-08-29
The regulator's established pharmacologic class for it is opioid antagonist [epc] and opioid antagonists [moa].
FDA National Drug Code directory · 72162-1566 · read 2026-08-29
48 published labels name it as an active ingredient. 47 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 7976b328-ad8e-4208-9f61-19cd5ab5f36b · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · 7976b328-ad8e-4208-9f61-19cd5ab5f36b · read 2026-08-29
Naltrexone Hydrochloride is film-coated tablets at 50 mg, recorded as prescription product; fda label in effect 2023-12-15 in the United States.
US prescribing information · 00c04ff4-b6f2-466c-9ab9-813a60577db0 · read 2026-08-27
Recorded price in US: 1.13919 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 21 priced products whose strengths and pack forms differ, as of 2026-08-26, paid by retail pharmacies buying the product, as surveyed by the Centers for Medicare & Medicaid Services. It is not a list price, an insurance price, or what anyone pays at a counter..
Recorded source · 2026-08-26 · read 2026-08-28
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.
RNAWiki could not confidently classify this substance, so no self-experiment plan is offered.
Questions worth asking
Which of the trials of Naltrexone studied people like me?
What was measured, and for how long?
Was the result a laboratory value or a health outcome?
What would we watch for, and when would we stop?
Tracking can show whether something changed for you. It cannot show what caused it.
RNAWiki records evidence. It does not say whether this substance is right for you.
What is missing or unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That naltrexone is inferior to buprenorphine once treatment has started — the per-protocol comparison in X:BOT showed no difference (P=0.44)
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the absence of a mortality association in the Larochelle cohort demonstrates no mortality benefit, when only 6% received naltrexone and for a median of one month
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That low-dose naltrexone relieves fibromyalgia pain, which the best randomised test did not find
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read from sources, not yet reviewed
What nobody knows yet
Open questions, each with why it is open and what would close it.
Missing populations
Which groups were under-represented in the studies has not been recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing long-term data
No completed tested study window is recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
No reviewed conclusion
RNAWiki has not yet published a reviewed conclusion for this use.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing interaction studies
No interaction was found in the registers checked. Not finding one is not the same as showing there is none.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Formulation uncertainty
Several salts, forms or products of Naltrexone are recorded. Results from one form may not transfer to another.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Mechanism not reviewed
No reviewed mechanism story exists for this substance.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
What happened in people◇Read from sources, not yet reviewed
Check any of this yourself
Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.
Every line above can be traced to the study named beside it. Follow the link and read it.
COMBINE: naltrexone reduced the risk of a heavy drinking day, acamprosate did not
In plain words
In the largest US trial of alcohol treatment, adding naltrexone to medical management cut the chance of a heavy drinking day by about a quarter. Acamprosate showed nothing in the same trial.
What was measured
Percent days abstinent, and hazard of a first heavy drinking day
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Anton et al. (NCT00006206) randomised 1,383 patients across eight groups. Percent days abstinent was 80.6 with naltrexone plus medical management, 79.2 with combined behavioural intervention plus medical management, 77.1 with both, and 75.1 with placebo plus medical management; the naltrexone-by-behavioural-intervention interaction was significant (P=.009). Naltrexone reduced the risk of a heavy drinking day over time (hazard ratio 0.72, 97.5% CI 0.53 to 0.98, P=.02), most evident in patients receiving medical management without the behavioural intervention. Acamprosate showed no significant effect alone or in any combination. One year after treatment the between-group effects were similar but no longer significant.
Written into the record, not signed off as a reviewed claim
Number needed to treat 12 to prevent return to heavy drinking
In plain words
Pooling 53 naltrexone trials, twelve people have to take it for one extra person to avoid returning to heavy drinking. That is a real effect and a modest one.
What was measured
Number needed to treat to prevent return to heavy drinking
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Jonas et al. included 122 randomised trials and one cohort study, 22,803 participants. For oral naltrexone 50 mg daily, the number needed to treat to prevent return to heavy drinking was 12 (95% CI 8 to 26; risk difference -0.09, 95% CI -0.13 to -0.04); to prevent return to any drinking it was 20 (95% CI 11 to 500). Acamprosate's NNT to prevent return to any drinking was 12 (8 to 26). Direct comparison of the two found no statistically significant difference. Number needed to harm for withdrawal from trials due to adverse events was 48 (30 to 112) for naltrexone.
Written into the record, not signed off as a reviewed claim
X:BOT: the injectable lost on intention to treat, entirely because of induction failure
In plain words
Extended-release naltrexone looked worse than buprenorphine overall, but almost all of the difference came from patients who never managed to start it. Among those who did start, the two were equal.
What was measured
Successful induction rate, and 24-week relapse by intention to treat
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Lee et al. (NCT02032433) randomised 570 patients with opioid use disorder. Induction succeeded in 204 of 283 (72%) assigned to extended-release naltrexone versus 270 of 287 (94%) assigned to buprenorphine-naloxone (P<0.0001). In the intention-to-treat population, 24-week relapse occurred in 185 of 283 (65%) versus 163 of 287 (57%), hazard ratio 1.36 (95% CI 1.10 to 1.68) — but 70 of the 79 naltrexone induction failures (89%) accounted for most or all of that difference. In the per-protocol population of 474 successfully inducted patients, relapse events were similar (P=0.44), as were opioid-negative urines and abstinent days. Five fatal overdoses occurred, two on naltrexone and three on buprenorphine.
Written into the record, not signed off as a reviewed claim
No mortality benefit demonstrated, and the comparison is not a fair one
In plain words
A large cohort study found reduced death rates with buprenorphine and methadone after an overdose, and no such association for naltrexone — but only 6% of the cohort received naltrexone and mostly for a month.
What was measured
That naltrexone does not reduce mortality in opioid use disorder — a conclusion the study itself declines to draw because of how few people received it and for how briefly
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Larochelle et al. followed opioid overdose survivors in Massachusetts. Methadone was associated with reduced all-cause mortality (adjusted hazard ratio 0.47, 95% CI 0.32 to 0.71) and opioid-related mortality (0.41, 0.24 to 0.70); buprenorphine with 0.63 (0.46 to 0.87) and 0.62 (0.41 to 0.92). No association was identified for naltrexone (all-cause AHR 1.44, 95% CI 0.84 to 2.46; opioid-related 1.42, 0.73 to 2.79). The authors explicitly flag the limitation: only 1,099 people (6%) received naltrexone, for a median of one month, against a median of four to five months for the agonists. This is an absence of evidence with a stated reason, not a demonstrated absence of effect.
Written into the record, not signed off as a reviewed claim
Krupitsky: extended-release naltrexone tripled confirmed abstinent weeks against placebo
In plain words
In a placebo-controlled trial in patients who had already completed detoxification, monthly naltrexone injections produced 90% confirmed abstinent weeks against 35% on placebo.
What was measured
Median proportion of weeks with confirmed opioid abstinence
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Krupitsky et al. randomised 250 patients (126 to extended-release naltrexone, 124 to placebo) in a multicentre Russian trial. Median proportion of weeks of confirmed abstinence was 90.0% (95% CI 69.9 to 92.4) versus 35.0% (11.4 to 63.8), P=0.0002. Self-reported opioid-free days were 99.2% versus 60.4% (P=0.0004). Median retention exceeded 168 days versus 96 days (P=0.0042). Naloxone challenge confirmed relapse to physiological dependence in 17 placebo patients versus one on naltrexone. Two patients in each group discontinued for adverse events; no naltrexone-treated patient died or overdosed. The trial enrolled only patients already detoxified, which is exactly the population X:BOT showed is hard to assemble in practice.
Written into the record, not signed off as a reviewed claim
Low-dose naltrexone did not beat placebo for fibromyalgia pain
In plain words
The best randomised test of low-dose naltrexone in fibromyalgia — a use widely promoted online — found no difference from placebo on pain.
What was measured
Between-group difference in pain intensity change
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Due Bruun et al. randomised 99 women with fibromyalgia to naltrexone 6 mg daily (n=49) or placebo (n=50) with no loss to follow-up. Mean change in pain intensity was -1.3 points (95% CI -1.7 to -0.8) on low-dose naltrexone and -0.9 (-1.4 to -0.5) on placebo, a between-group difference of -0.34 (95% CI -0.95 to 0.27; p=0.27, Cohen's d 0.23). Adverse events occurred in 84% versus 86%. The authors reported a possible signal on memory symptoms and recommended it be investigated. An accompanying commentary in the same journal was titled "Is low-dose naltrexone for fibromyalgia another treatment disappointment?"
This order is fixed in code and does not count clicks or time on the page.
What is not here
3 questions this page could not answer
These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.
What it may clash with — found nothing in the sources checked.
Other ways to the same goal — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
The full record, for auditing
Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.
The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
An opioid receptor blocker with a modest but replicated effect in alcohol use disorder (number needed to treat 12 to prevent return to heavy drinking), and an opioid indication whose real-world limitation is not the drug but the detoxification required before it can be started.
Recorded evidence blocks (16)
Q1
What did Naltrexone's largest trial (7500 people) and its longest (21 years) measure?
7500 people in Naltrexone's largest registered study, 21 years in its longest registered window, measuring Measure area under the fentanyl concentration-time curve (AUC). ClinicalTrials.gov · 2026-09-01
113 phase2, 65 phase4, 52 phase3, 41 phase1, 22 na, 9 early phase1, 3 na or unstated; NCT00439049; 2026-06. Last human test completed 2026, NCT07132177.
Interpretation These counts include studies where Naltrexone was a comparison treatment, a background treatment or an exposure in an observational study, and the longest window may be a planned end date. Trial roles have not yet been classified for this record.
Show the evidence
phase2
113
phase4
65
phase3
52
phase1
41
na
22
early phase1
9
2 more recorded rows
na or unstated
3
Last recorded human testNCT07132177
2026-04-01
recorded 2026-09-01 · last checked 2026-09-04
Q2
From C. elegans to human: where has Naltrexone shown lifespan?
Interpretation Measure area under the fentanyl concentration-time curve (AUC) — the recorded outcome words.
Show the evidence
C. elegans
lifespan
mouse
lifespan
rat
mechanism-only
dog
mechanism-only
humanNCT01750060
biomarker; Measure area under the fentanyl concentration-time curve (AUC); 283
recorded 2026-09-01 · last checked 2026-09-04
Q3
33 of Naltrexone's trials stopped: accrual/recruitment, funding/business, other?
accrual/recruitment (13), funding/business (9) and other (11): Naltrexone's stop wording, clustered. ClinicalTrials.gov · 2026-09-01
"Difficulties in recruiting enough subjects"; 33 of 283 registered studies
Show the evidence
Trial
NCT00124839
terminated; "Difficulties in recruiting enough subjects"
NCT00156936
terminated; "Business decision"
NCT00379197
terminated; "slow accrual"
NCT00398008
withdrawn; "Study was never able to start in IRAN"
NCT00467454
withdrawn; "Funding allocation to different clinical trials."
NCT00854230
withdrawn; "We expanded to a bigger, multi-site study \& decided to close this study."
14 further recorded trials
NCT01015066
withdrawn; "Study personnel left institution, anticipated funding did not occur"
NCT01155869
terminated; "Poor enrollment"
NCT01638377
terminated; "Recruitment proved to be extremely difficult."
NCT01650350
terminated; "Study stopped 10/24/13 secondary to lack of patients/slow enrollment"
NCT01721330
terminated; "Competing studies"
NCT01810185
withdrawn; "Low patient enrollment"
NCT02137252
terminated; "no enough patients"
NCT02726035
withdrawn; "PI deceased"
NCT02965768
withdrawn; "Study was temporarily suspended to focus on other projects, but was never resumed. No participants were determined eligible and none started the protocol."
NCT03113409
terminated; "no funding available to continue"
NCT03132571
terminated; "Study discontinued due to funding."
NCT03854942
terminated; "Recruitment rate could not be met in the study period, review group was dissolved before regular end of study. Recruitment was therefore terminated."
NCT03970330
terminated; "Original PI left institution, lack of funding to continue"
NCT04094584
terminated; "12 month follow up data not collected due to pandemic disruptions"
recorded 2026-09-01 · last checked 2026-09-04
Q4
Human studies of Naltrexone used Naltrexone 50 Mg — over how long?
More Naltrexone was worse in human: at what point?
Hormetic in human: "However, naltrexone at low doses has been shown to have hormetic effects and provides relief for chronic pain conditions such as fibromyalgia, multiple sclerosis (MS), and inflammatory bowel disorders." Europe PMC · dose-response search · 2024-03-15
6 recorded sentences naming Naltrexone; hormetic, dose-response, biphasic
Show the evidence
hormeticPMID 37371715
"However, naltrexone at low doses has been shown to have hormetic effects and provides relief for chronic pain conditions such as fibromyalgia, multiple sclerosis (MS), and inflammatory bowel disorders."
dose-responsePMID 37699710
"Results show that naltrexone produced: 1) a 10-fold rightward shift in the dose-response function for the reinforcing effects of oxycodone, and 2) in reinstatement and antinociception experiments, comparable rightward shifts in the dose-response functions for higher-efficacy MOR agonists (methadone, heroin, and oxycodone) but rightward and downward shifts in the dose-response functions for…"
biphasicPMID 37371715
"Naltrexone is an oral-activated opioid antagonist with biphasic dose-dependent pharmacodynamic effects."
dose-response
PMID 37245850
"The administration of the opioid receptor antagonists naloxone, naltrexone and nalmefene led to progressive, parallel rightward shifts of the dose-response curves."
PMID 32068870
"This study explores dose-response relationships when treating fibromyalgia with low-dose naltrexone."
PMID 32068870
"This study is the first to explore dose-response relationships in the treatment of fibromyalgia with low-dose naltrexone."
recorded 2024-03-15 · last checked 2026-09-04
Q6
Naltrexone's half-life is 4 hours — which schedules were studied?
4 hours, the half-life Naltrexone's label states. openfda-label · 57e8b767-54c2-dfa3-e063-6394a90ae6c2 · 2026-08-27
bioavailability 5 to 40% %.
Show the evidence
half life
4 hours hours; The mean elimination half-life (T 1/2 ) values for naltrexone and 6-β-naltrexol are 4 hours and 13 hours, respectively.
bioavailability
5 to 40% %; Although well absorbed orally, naltrexone is subject to significant first pass metabolism with oral bioavailability estimates ranging from 5 to 40%.
metabolism
Although well absorbed orally, naltrexone is subject to significant first pass metabolism with oral bioavailability estimates ranging from 5 to 40%.
recorded 2026-08-27 · last checked 2026-09-04
Q7
Could one person measure Naltrexone's effect on days abstinent?
Days abstinent: measured in Naltrexone's trials.
Interpretation days abstinent is the recorded endpoint.
Show the evidence
biomarkers
days abstinent; 2026-09-01
retention; 2026-09-01
cocaine use; 2026-09-01
depression; 2026-09-01
anxiety; 2026-09-01
addiction severity; 2026-09-01
14 more recorded rows
biomarkers
global improvement; 2026-09-01
biomarkers
alcohol use; 2026-09-01
biomarkers
heavy drinking days; 2026-09-01
biomarkers
time to relapse; 2026-09-01
biomarkers
time to lapse; 2026-09-01
biomarkers
drinks per drinking day; 2026-09-01
biomarkers
retention in treatment; 2026-09-01
biomarkers
smoking cessation; 2026-09-01
biomarkers
prevalence abstinence; 2026-09-01
biomarkers
weight gain; 2026-09-01
biomarkers
urine toxicology for cocaine; 2026-09-01
biomarkers
obsessive compulsive drinking scale; 2026-09-01
biomarkers
clinician administered ptsd scale; 2026-09-01
biomarkers
hamilton depression rating scale; 2026-09-01
half life
2026-09-04; halfLife; hours; 4 hours; 2026-08-27
human trials at or under30
91
smallest human trial
0; NCT00000195; PHASE2; the smallest recorded human enrolment at or below 30; the registry states no direction of its result; WITHDRAWN
Q8
Which of addiction severity, adult investigator symptom rating scale and adverse events as a measure of safety and tolerability did Naltrexone's trials measure?
addiction severity, adult investigator symptom rating scale and adverse events as a measure of safety and tolerability lead 40 outcome terms across Naltrexone's trials. ClinicalTrials.gov · 2026-09-01
Interpretation depression, anxiety, addiction severity, global improvement, alcohol use and heavy drinking days follow.
Show the evidence
days abstinent
1
retention
1
cocaine use
1
depression
1
anxiety
1
addiction severity
1
14 more recorded rows
global improvement
1
alcohol use
1
heavy drinking days
1
time to relapse
1
time to lapse
1
drinks per drinking day
1
retention in treatment
1
smoking cessation
1
prevalence abstinence
1
weight gain
1
urine toxicology for cocaine
1
obsessive compulsive drinking scale
1
clinician administered ptsd scale
1
hamilton depression rating scale
1
recorded 2026-09-01 · last checked 2026-09-04
Q9
Which of Naltrexone's 25 ongoing trials reports first?
Fear Response directly post-extinction; Retention: Continuous retention in MOUD treatment through 26 weeks; latest 2034-10-23
Show the evidence
Trial
NCT04166071
"Opioids and Social Support Enhanced Extinction Effects"; n 60; "Fear Response directly post-extinction"; 2026-09
NCT04464980
"Optimizing Retention, Duration and Discontinuation Strategies for Opioid Use Disorder Pharmacotherapy (RDD)"; n 1516; "Retention: Continuous retention in MOUD treatment through 26 weeks"; 2027-01-31
NCT04649892
"Predicting Response to Naltrexone With Eye Tracking in Gaming Disorder"; n 40; "Adpated Internet Gaming Disorder Scale-Short Form (IGDS9-SF)"; 2027-07
NCT04678895
"Low-Dose Naltrexone for the Treatment of Painful Diabetic Neuropathy"; n 35; "Change in Pain Disability Index"; 2026-12
NCT05007561
"Understanding How Opioids Affect the Experiential and Neural Signatures of Social Experiences"; n 210; "Daily feelings of social connection via ecological momentary assessment"; 2027-07
NCT05509257
"Naltrexone Neuroimaging in Teens With Eating Disorders"; n 60; "Response"; 2027-06
14 further recorded trials
NCT05827159
"Emergency Department-Initiated Medications for Alcohol Use Disorder"; n 240; "Participation in AUD Treatment on Day 30 post-randomization"; 2029-02-01
NCT05940324
"Examining Mu Opioid Mechanisms of Ketamine's Rapid Effects in OCD (MKET2)"; n 150; "Change in the severity of OCD symptoms as measured by the Yale-Brown Obsessive Compulsive Scale (YBOCS)"; 2028-11
NCT05955313
"Effectiveness of Low-dose Naltrexone in Patients With Different Types of Vulvodynia"; n 300; "Treatment effectiveness - change in pain intensity"; 2026-12-31
NCT05968690
"Naltrexone and Propranolol Combined With Immunotherapy"; n 12; "Safety as assessed by Common Terminology Criteria for Adverse Events (CTCAE) v5.0"; 2027-09-30
NCT06233799
"Trial of Naltrexone/Bupropion for the Treatment of Methamphetamine Use Disorder"; n 360; "Number of Participants with at least 75% methamphetamine-negative urine drug screen tests during the evaluation period (i. e., Weeks 11-12)"; 2027-04-30
NCT06426303
"Sex Differences in Trauma, Inflammation and Brain Function and the Implications for Treatment Efficacy in Alcohol Use Disorder"; n 100; "Change from baseline in alcohol use (number of drinking days, amount used per day)"; 2028-12-31
NCT06622239
"Trial to Evaluate the Effects of Naltrexone in Nonsuicidal Self-injury"; n 150; "Frequency of nonsuicidal self-injurous behavior"; 2027-05-31
NCT06845124
"A Trial to Investigate the Effects of Cannabidiol Plus Naltrexone on Alcohol Craving in Patients With Alcohol Dependence"; n 150; "Obsessive Compulsive Drinking Scale (OCDS-G)"; 2028-09-30
NCT07092618
"Effectiveness of Alternative Therapies in Maintaining Weight Loss Achieved by GLP-1 Medications Post-Cessation"; n 150; "Evaluate the effectiveness of metformin in maintaining GLP1-induced weight loss in participants weaning off of Ozempic or Wegovy (or compounded semaglutide equivalent)"; 2025-08
NCT07221565
"Electromagnetic Immunotherapy Mapping and Cytokine Forecasting Study (QSIT)"; n 120; "Change in Autoimmune Flare Frequency"; 2034-10-23
NCT07224009
"Low Dose Naltrexone (LDN) for Management of Fatigue in Prostate Cancer Patients on Androgen Deprivation Therapy (ADT)"; n 60; "Characterize mitochondrial bioenergetics after ADT and the remediating effects of LDN"; 2030-01
NCT07224087
"Development of a MHBC Intervention for Weight Loss and Smoking Cessation for Pre-Bariatric Surgery Patients"; n 20; "Study enrollment to assess Feasibility"; 2027-12-31
NCT07249554
"Combination Therapy for Alcohol Use Disorder"; n 45; "Participant-reported Adverse Events"; 2028-09
NCT07269873
"Safety and PK Study of BICX104 With or Without Bupropion Compared to Vivitrol"; n 30; "Cmax"; 2026-12-05
recorded 2026-09-01 · last checked 2026-09-04
Q10
Which running trial of Naltrexone could settle vo2max?
NCT07475546 measures Change in cardiorespiratory fitness measured by maximal oxygen uptake (VO₂ max), reading out 2026-04.
1 open trial; n 30; "Combination Gerotherapeutic Interventions for Healthspan Improvement"
Show the evidence
TrialNCT07475546
"Combination Gerotherapeutic Interventions for Healthspan Improvement"; n 30; "Change in cardiorespiratory fitness measured by maximal oxygen uptake (VO₂ max)"; 2026-04
Q11
Which 94 trials of Naltrexone posted no result?
Posted no result
94 of 94 completed trials
Registrations
NCT00015080, NCT00000449, NCT00000448, NCT00018213, NCT01133301 and NCT00000450, and 88 more
Completion dates
oldest 1996-07; newest 2023-04-26
Show the evidence
Trial
NCT00015080
1996-07
NCT00000449
2000-03
NCT00000448
2000-12
NCT00018213
2001-03
NCT01133301
2001-10
NCT00000450
2002-02-13
14 further recorded trials
NCT00238914
2002-07
NCT00000456
2002-08
NCT00000440
2002-09
NCT00000445
2002-09
NCT00000455
2002-09
NCT00000442
2002-12
NCT00000452
2003-01
NCT00000438
2003-03
NCT00000447
2003-05
NCT00714584
2003-06
NCT00167232
2003-07
NCT00218153
2004-04
NCT00326807
2004-06
NCT00027079
2004-08
Q12
At the median, Naltrexone's trials enrolled 60 people — anything larger?
Median enrolment
60
Largest enrolment
7500
Registered trials counted
280
Q13
What do 1054 spontaneous reports say about Naltrexone — and not say?
These are reports people sent to a regulator. They do not show the medicine caused the reaction. Nobody counted how many people took the medicine and reported nothing. The same event can be reported more than once, and many reports are incomplete. News coverage, lawsuits and new warnings change how often people report. A count is not a rate and not a risk.
Naltrexone appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 1054 reaction mentions were counted: nausea 298; dizziness 146; headache 135; vomiting 114. open-targets-adr · CHEMBL1201149 · 2026-06-24
Show the evidence
nausea
298
dizziness
146
headache
135
vomiting
114
feeling abnormal
110
insomnia
60
4 more recorded rows
constipation
57
anxiety
52
hyperhidrosis
43
somnolence
39
recorded 2026-06-24 · last checked 2026-09-04
Q14
Naltrexone and CYP1A2 and CYP3A4: shared by which compounds?
CYP1A2 and CYP3A4 appear in Naltrexone's recorded interaction sentences, 3 in all. openfda-label+europepmc · 2026-08-30
Interpretation pharmacokinetics
Show the evidence
CYP1A2
pharmacokinetics
An in vitro CYP inhibition study demonstrated that naltrexone is not an inhibitor of major CYP enzymes (CYP 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 3A4).
pharmacokinetics
An in vitro CYP induction study demonstrated that naltrexone is not an inducer of CYP3A4 and CYP1A2.
CYP3A4pharmacokinetics
An in vitro CYP induction study demonstrated that naltrexone is not an inducer of CYP3A4 and CYP1A2.
recorded 2026-08-30 · last checked 2026-09-04
Q15
Was Naltrexone studied with fasting and exercise?
fasting and exercise are named in Naltrexone's label sentences: "In this open-label, randomized, cross-over study, the enrolled patients were randomised to receive a single dose of 40 mg OTR or 40 mg OXYCONTIN<sup>®</sup> (OXY) tablet administered with naltrexone blockade under fasting conditions." openfda-label+europepmc · 2026-08-30
2 recorded statements; fasting, exercise
Show the evidence
fasting
In this open-label, randomized, cross-over study, the enrolled patients were randomised to receive a single dose of 40 mg OTR or 40 mg OXYCONTIN<sup>®</sup> (OXY) tablet administered with naltrexone blockade under fasting conditions.
exercise
Participants were administered (randomized, double-blind, counterbalanced procedure) an opioid antagonist (i.e., naltrexone) and a placebo prior to performing pain testing and isometric exercise.
recorded 2026-08-30 · last checked 2026-09-04
Q16
What is recorded about Naltrexone and NAD+?
"In this pilot study, we assessed whether treatment with low-dose naltrexone (LDN, 4.5 mg/day) and supplementation with NAD + through iontophoresis patches could improve fatigue symptoms and quality of life in 36 patients with persistent moderate/severe fatigue after COVID-19." — where Naltrexone and NAD+ appear together. Europe PMC · pathway abstract search · 2024-02-01
"In this pilot study, we assessed whether treatment with low-dose naltrexone (LDN, 4.5 mg/day) and supplementation with NAD + through iontophoresis patches could improve fatigue symptoms and quality of life in 36 patients with persistent moderate/severe fatigue after COVID-19."
mTOR
PMID 34445130
"In a dose-dependent manner, naltrexone also modulated mTOR/S6K expression, which underlies the cell metabolic phenotype regulating microglia immune properties and adaptation."
PMID 31667579
"Likewise, the PI3K/AKT/mTOR pathway was significantly inhibited by 1% Naltrexone HCl in XemaTop™, suggesting protein synthesis was affected."
NAD+PMID 4039802
"It is suggested that pharmacokinetic antagonism of acute alcohol intoxication by naloxone and naltrexone is unrelated to the property of opiate antagonism, but may involve the ability of certain such antagonists to interact with hepatic NAD+-dependent oxidative metabolism."
recorded 2024-02-01 · last checked 2026-09-04
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