naltrexone (Rx)

Brand and Other Names:ReVia, Vivitrol, more...Depade

Dosing & Uses


Dosage Forms & Strengths


  • 50mg

microspheres for IM injection

  • 380mg

Opioid Dependence

Prevention of relapse after opioid detoxification; to be used only after patient has been opioid-free for 7-10 days and after negative naloxone challenge (no symptom withdrawal after naloxone administration)

PO: 25 mg initially, then observation for 1 hr, then 50 mg once daily starting on day 2; flexible dosing regimens can be employed to accommodate patient convenience or ensure compliance

IM: 380 mg in gluteal muscle every 4 weeks for maintenance of abstinence

Alcohol Dependence

Treatment in patients who have been able to abstain from alcohol in outpatient settings before treatment initiation

PO: 50 mg once daily for ≤12 weeks

IM: 380 mg in gluteal muscle every 4 weeks for maintenance of abstinence

Dosing Considerations

Administer only as a deep intramuscular gluteal injection only

Hepatitis (Orphan)

Orphan designation for treatment of autoimmune hepatitis


  • TaiwanJ Pharmaceuticals Co., Ltd, Room 204 A, Bldg 53; 195 Chung Hsing Rd., Sec 4; Chutung, Hsinchu, Taiwan

Postherpetic Neuralgia (Orphan)

Orphan designation for treatment of postherpetic neuralgia


  • Allodynic Therapeutics, LLC; 1785 NE 123rd Street; North Miami, FL 33181-2537

Safety and efficacy not established

Crohn Disease (Orphan)

Treatment in pediatric patients

Orphan indication sponsor

  • Jill P Smith, MD, Pennsylvania State University, 500 University Drive, Hershey, PA 17033


Interaction Checker

and naltrexone

No Results

     activity indicator 
    No Interactions Found
    Interactions Found


      Serious - Use Alternative

        Significant - Monitor Closely


            All Interactions Sort By:
             activity indicator 

            Contraindicated (0)

              Serious - Use Alternative (3)

              • bremelanotide

                bremelanotide will decrease the level or effect of naltrexone by Other (see comment). Avoid or Use Alternate Drug. Bremelanotide may slow gastric emptying and potentially reduces the rate and extent of absorption of concomitantly administered oral medications. Avoid using bremelanotide with an orally administered naltrexone-containing product that is intended to treat alcohol and opioid addiction due to the potential for naltrexone treatment failure.

              • naldemedine

                naldemedine, naltrexone. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Potential for additive opioid receptor anatagonism and increased risk of opioid withdrawal.

              • naloxegol

                naloxegol, naltrexone. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration; potential for additive effect of opioid receptor anatagonism and increased risk of opioid withdrawal.

              Monitor Closely (5)

              • acamprosate

                naltrexone increases levels of acamprosate by unspecified interaction mechanism. Use Caution/Monitor. No dosage adjustment is needed.

              • apalutamide

                apalutamide will decrease the level or effect of naltrexone by increasing elimination. Use Caution/Monitor. Apalutamide induces UGT and may decrease systemic exposure of drugs that are UGT substrates.

              • dronabinol

                naltrexone increases effects of dronabinol by Other (see comment). Use Caution/Monitor. Comment: Naltrexone may enhance therapeutic effects of cannabinoids. .

              • lofexidine

                lofexidine will decrease the level or effect of naltrexone by unknown mechanism. Modify Therapy/Monitor Closely. Coadministration of lofexidine with oral naltrexone resulted in statistically significant differences in the steady-state pharmacokinetics of naltrexone. The efficacy of oral naltrexone may be reduced if administered within 2 hours of taking lofexidine. Interaction not expected with other naltrexone routes of administration.

              • nabilone

                naltrexone increases effects of nabilone by Other (see comment). Use Caution/Monitor. Comment: Naltrexone may enhance therapeutic effects of cannabinoids. .

              Minor (0)


                Adverse Effects


                Injection site reaction (69%; includes bruising, induration, nodules, pain, pruritus, swelling, tenderness)

                Nausea (33%)

                Headache (25%)

                Decreased appetite (14%)

                Insomnia (14%)

                Vomiting (14%)

                Diarrhea (13%)

                Dizziness (13%)

                Upper respiratory tract infection (URTI) (13%)

                Anxiety (12%)

                Arthralgia (12%)

                Increased creatine phosphokinase (11%)

                Pharyngitis (11%)


                Depression (8%)

                Muscle cramps (8%)

                Back pain (6%)

                Rash (6%)

                Dry mouth (5%)

                Somnolence (4%)

                Increased aspartate aminotransferase (AST) (2%)





                Hepatocellular injury

                Increased systolic and diastolic blood pressures

                Liver function abnormalities

                Labored breathing

                Nonspecific electrocardiographic (ECG) changes

                Opiate withdrawal (mild to severe signs and symptoms, including drug craving, confusion, drowsiness, visual hallucinations, abdominal pain, vomiting, diarrhea)




                Postmarketing Reports

                Hypersensitivity reactions, including anaphylaxis




                Patients who are on opioid analgesics, are opioid-dependent (eg, opioid agonists [methadone], opioid partial agonists [buprenorphine]), are in acute opioid withdrawal, have positive urine test for opioids, or fail to pass naloxone challenge



                Administer as a deep intramuscular gluteal injection; inadvertent subcutaneous injection may increase likelihood of severe injection site reactions; the needles provided in the carton are customized needles

                Depression, suicide, and suicidality cited in postmarketing reports; causal relation not demonstrated

                Vulnerability to opioid overdose: Patients should be alerted that they may be more sensitive to opioids, even at lower doses, after discontinuance of naltrexone

                Opioid withdrawal precipitated abruptly by administration of opioid antagonist to opioid-dependent patient may result in withdrawal syndrome severe enough to necessitate hospitalization (see Contraindications)

                Risk of hepatotoxicity with increasing doses; dose related hepatocellular injury; discontinue therapy if signs/symptoms of acute hepatitis develop

                Injection may cause severe injection-site reactions (eg, cellulitis, necrosis, hematoma); may be followed by pain, tenderness, induration, swelling, erythema, bruising, or pruritus; however, in some cases injection site reactions may be very severe andmay last for several weeks following administration

                Injectable microspheres are for IM use only; inadvertent SC/IV administration may increase risk of severe injection-site reactions

                Cases of eosinophilic pneumonia reported; consider in patients with symptoms of progressive hypoxia and dyspnea

                Use caution in patients with hepatic failure or with bleeding disorder including thrombocytopenia and hemophilia, or patients taking anticoagulant therapy; beeding hematoma may occur from IM administration

                Use caution in renal impairment or hepatic impairment

                Patients should be opioid free for a minimum of 7-10 days before initiating therapy; a naltrexone challenge test recommended to confirm opioid-free status

                Emergency treatment of opioid overdose

                • At initial and subsequent naltrexone injections discuss with patient and caregiver the availability of naloxone for the emergency treatment of opioid overdose
                • Inform patients and caregivers of options for obtaining naloxone as permitted by individual state naloxone dispensing and prescribing requirements or guidelines (eg, by prescription, directly from a pharmacist, or as part of a community-based program); strongly consider prescribing naloxone for emergency treatment of opioid overdose
                • Educate patients and caregivers on how to recognize signs and symptoms of an opioid overdose and, if naloxone is prescribed, how to treat with naloxone; emphasize importance of calling 911 or getting emergency medical help in all cases of known or suspected opioid overdose, even if naloxone is administered

                Pregnancy & Lactation


                The available data from published case series with use in pregnant women are insufficient to identify a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes

                Untreated opioid addiction in pregnancy is associated with adverse obstetrical outcomes such as low birth weight, preterm birth, and fetal death; in addition, untreated opioid addiction often results in continued or relapsing illicit opioid use

                Published studies have demonstrated that alcohol is associated with fetal harm including growth restriction, facial abnormalities, central nervous system abnormalities, behavioral disorders, and impaired intellectual development


                The drug and metabolites, are present in human milk; there are no data on effects on breastfed infant or on milk production

                Developmental health benefits of breastfeeding should be considered along with mother’s clinical need for naltrexone and any potential adverse effects on breastfed infant from drug or mother’s underlying maternal condition

                Pregnancy Categories

                A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

                B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

                C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

                D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

                X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

                NA: Information not available.



                Mechanism of Action

                Opioid competitive receptor antagonist; shows highest affinity for mu receptors; congener of oxymorphone


                96% absorbed from gastrointestinal tract, but because of first-pass metabolism, only 5-40% reaches systemic circulation

                Bioavailability: 5-40%

                Onset: 15-30 min

                Duration: 24 hr

                Peak plasma time: PO tablet, 1 hr; PO solution, 0.6 hr

                Peak plasma concentration (50-mg dose): Naltrexone, 10.6-13.7 ng/mL; 6-β-naltrexol, 109-139 ng/mL


                Protein bound: 21-28%

                Vd: 1350 L


                Metabolized in liver

                Metabolites: 6-β-naltrexol (major), 2-hydroxy-3-methoxy-6-β-naltrexol (HMN), 2-hydroxy-3-metho-xynaltrexone, noroxymorphone, 3-methoxy-6-β-naltrexol


                Half-life: PO, 4 hr; 6-β-naltrexol, 13 hr; IM and 6-β-naltrexol and IM: 5-10 days

                Excretion: Urine (mainly)



                IM Administration

                Administer IM as gluteal injection, alternating buttocks for each subsequent injection

                Drug must be prepared and administered by a healthcare provider



                naltrexone oral
                50 mg tablet
                naltrexone oral
                50 mg tablet
                naltrexone oral
                50 mg tablet
                naltrexone oral
                50 mg tablet
                naltrexone oral
                50 mg tablet

                Copyright © 2010 First DataBank, Inc.


                Patient Handout

                Patient Education
                naltrexone oral

                NALTREXONE - ORAL


                COMMON BRAND NAME(S): Revia

                USES: This medication is used to prevent people who have been addicted to certain drugs (opiates) from taking them again. It is used as part of a complete treatment program for drug abuse (such as compliance monitoring, counseling, behavioral contract, lifestyle changes). This medication must not be used in people currently taking opiates, including methadone. Doing so can cause sudden withdrawal symptoms.Naltrexone belongs to a class of drugs known as opiate antagonists. It works in the brain to prevent opiate effects (such as feelings of well-being, pain relief). It also decreases the desire to take opiates.Ask your doctor or pharmacist if you should have naloxone available to treat opioid overdose. Teach your family or household members about the signs of an opioid overdose and how to treat it.This medication is also used to treat alcohol abuse. It can help people drink less alcohol or stop drinking altogether. It also decreases the desire to drink alcohol when used with a treatment program that includes counseling, support, and lifestyle changes.

                HOW TO USE: Take this medication by mouth with or without food as directed by your doctor, usually once daily. This medication may be given as part of a program where a health care professional will watch you take the medication. In this case, this medication may be taken every 2 to 3 days to make it easier to schedule clinic visits. Naltrexone may be taken with food or antacids if stomach upset occurs.A urine test should be done to check for recent opiate drug use. Your doctor may give you another medication (naloxone challenge test) to check for opiate use. Do not use any opiates for at least 7 days before starting naltrexone. You may need to stop certain opiate drugs (such as methadone) 10 to 14 days before starting naltrexone.The dosage is based on your medical condition and response to treatment. Your doctor may start you at a lower dose and monitor you for any side effects or withdrawal symptoms before increasing your dose. Take this medication as directed. Do not increase your dose, take it more often, or stop taking it without your doctor's approval.Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day.Tell your doctor if you start using drugs (opiates) or alcohol again.

                SIDE EFFECTS: Nausea, headache, dizziness, anxiety, tiredness, and trouble sleeping may occur. In a small number of people, mild opiate withdrawal symptoms may occur, including abdominal cramps, restlessness, bone/joint pain, muscle aches, and runny nose. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Sudden opiate withdrawal symptoms can occur within minutes after taking naltrexone. Tell your doctor right away if any withdrawal symptoms occur, including: abdominal cramps, nausea/vomiting, diarrhea, joint/bone/muscle aches, mental/mood changes (such as anxiety, confusion, extreme sleepiness, visual hallucinations), runny nose.Naltrexone has rarely caused serious liver disease. The risk is increased when larger doses are used. Discuss the risks and benefits with your doctor. Tell your doctor right away if you develop symptoms of liver disease, including: nausea/vomiting that doesn't stop, severe stomach/abdominal pain, dark urine, yellowing eyes/skin.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

                PRECAUTIONS: Before taking naltrexone, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: current or recent use (in the last 7 to 14 days) of any type of opioid drug (such as morphine, methadone, buprenorphine), kidney disease, liver disease.You should carry or wear medical identification stating that you are taking this drug so that appropriate treatment can be given in a medical emergency.This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).After stopping naltrexone treatment, you may be more sensitive to lower doses of opioids, increasing your risk of possibly life-threatening side effects from the opioid (such as decreased breathing, loss of consciousness).This medication blocks the effects of opiate drugs (including heroin) and similar drugs (opioids). However, large doses of heroin or opioids can overcome this block. Trying to overcome this block is very dangerous and may cause serious injury, loss of consciousness, and death. Make sure you completely understand and accept the risks and benefits of using this medication. Follow your doctor's instructions closely.Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.This drug passes into breast milk. Consult your doctor before breast-feeding.

                DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug include: dextromethorphan, diarrhea medication (such as diphenoxylate), disulfiram, opioid pain or cough relievers (such as codeine, hydrocodone), thioridazine.This medication may interfere with certain lab tests (such as drug tests), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

                OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.

                NOTES: Do not share this medication with others.Lab and/or medical tests (such as liver function) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

                MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

                STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

                Information last revised August 2023. Copyright(c) 2023 First Databank, Inc.

                IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.



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                1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
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