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Generic Name: naltrexone

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An antidote - treats Alcohol Dependence and Opiate Dependence

FDA Alerts

Hepatic Effects

Possible dose-related hepatotoxicity. Margin between therapeutic and hepatotoxic dosages may be less than fivefold; hepatotoxicity not apparent at usual dosages. (See Hepatic Effects under Cautions.)
Contraindicated in patients with acute hepatitis or liver failure; carefully weigh potential benefits against possible hepatotoxic risks in patients with active liver disease.
Instruct patients to discontinue naltrexone and contact a clinician if manifestations of acute hepatitis occur. (See Advice to Patients.)

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(nal TREX own)

Uses

Opiate Dependence

Used as an adjunct to a medically supervised behavior modification program in the maintenance of opiate cessation (opiate-free state) in individuals who were formerly physically dependent on opiates and who have successfully undergone detoxification (designated an orphan drug by FDA for this use).

Behavior modification is an integral component in maintaining opiate cessation; behavior modification programs involve supervised programs of counseling, psychologic support and therapy, education, and changes in life-style (social rehabilitation).

May diminish or eliminate opiate-seeking behavior by blocking opiate euphoria and by preventing the conditioned abstinence syndrome (i.e., heightened sensitivity to stimuli, abnormal autonomic responses, dysphoria, intense opiate craving) that occurs following opiate withdrawal.

Efficacy in maintaining long-term cessation appears to be low; poor compliance appears to be the major limiting factor. Because noncompliance with naltrexone is not associated with unpleasant symptoms of withdrawal, compliance depends more on voluntary efforts; successful cessation may be more likely in highly motivated individuals.

Has been used for rapid or ultrarapid detoxification in the management of opiate withdrawal† in opiate-dependent individuals, both in inpatient and outpatient settings.

Rapid opiate detoxification involves the administration of opiate antagonists (e.g., naltrexone and/or naloxone) to shorten the time period of detoxification.

Ultrarapid detoxification is similar but involves the administration of opiate antagonists while the patient is sedated or under general anesthesia.Consider the risk of adverse respiratory and cardiovascular effects associated with this procedure, as well as the costs of general anesthesia and hospitalization.

Alcohol Dependence

Management of alcohol dependence in conjunction with a behavior modification program involving supervised programs of counseling, psychologic support and therapy, and education and changes in life-style (social rehabilitation).

Used IM in individuals who are able to abstain from alcohol in an outpatient setting and are abstinent when treatment is initiated.

Behavior modification is an integral component in maintaining alcohol cessation; naltrexone has not been shown to provide any therapeutic benefit except as part of an appropriate plan of addiction management.

When used in conjunction with behavior modification, naltrexone reportedly decreases alcohol craving, reduces alcohol consumption, decreases the number of drinking days, maintains abstinence from alcohol ingestion, and prevents, decreases, or ameliorates the severity of relapse.

Naltrexone is not uniformly effective; the expected effect is a modest improvement in the outcome of conventional therapy.

Dosage and Administration

General

Verification of Opiate Abstinence Prior to Initiation of Therapy

Patients who are physically dependent on opiates should complete detoxification prior to initiation of naltrexone therapy.
Manufacturers recommend that at least 7–10 days elapse between discontinuance of opiates and initiation of naltrexone therapy because of the risk of precipitating opiate withdrawal (see Accidental Precipitation of Withdrawal under Cautions.) This waiting period may vary depending on the dose and duration of action of the opiate; allow at least 7 days in patients using relatively short-acting opiates (e.g., heroin, hydromorphone, meperidine, morphine) and at least 10–14 days in those using longer-acting opiates (e.g., methadone).
Some clinicians have cautiously precipitated withdrawal using repeated naloxone injections and then rapidly initiated naltrexone therapy with incremental doses of the drug; this procedure can reduce the transition period from opiate dependence to naltrexone maintenance and generally is well accepted by patients.
In addition to patient verification of abstinence from opiates, perform urinalysis after the minimum 7- to 10-day waiting period, but prior to administration of naltrexone, to confirm the absence of opiates. If it is uncertain whether the patient is opiate free, perform a naloxone challenge test prior to administering naltrexone.

Naloxone Challenge Test

Perform test prior to induction of naltrexone therapy in patients formerly physically dependent on opiates who have completed detoxification and in those suspected of having been dependent on opiates.
Test should not be performed in patients who are exhibiting signs and/or symptoms of opiate withdrawal, those whose urine shows evidence of opiates, or those in whom there is a high degree of suspicion that opiates are still being used, since naloxone may precipitate potentially severe opiate withdrawal.
Do not attempt naltrexone therapy if signs and/or symptoms of opiate withdrawal (e.g., nasal stuffiness, rhinorrhea, lacrimation, yawning, sweating, tremor, abdominal cramps, vomiting, piloerection, myalgia, skin crawling) are evident following administration of the naloxone challenge test; instead, repeat the naloxone challenge test in 24 hours.
Naloxone may be administered IV or sub-Q in the challenge test.
IV challenge test: Draw 0.8 mg of naloxone hydrochloride into a syringe. Administer 0.2 mg initially; while the needle remains in the vein observe the patient for 30 seconds for evidence of opiate withdrawal. Alternatively, some clinicians recommend 15 minutes for the period of observation. If no evidence of withdrawal is observed, inject the remaining 0.6-mg dose and observe the patient for an additional 20 minutes for evidence of withdrawal.
Sub-Q challenge test: Draw 0.8 mg of naloxone hydrochloride into a syringe. Inject the entire 0.8-mg dose and observe the patient for 20 minutes for evidence of opiate withdrawal.
If evidence of opiate withdrawal is present, delay naltrexone therapy and repeat the naloxone challenge test in 24 hours with the 0.8-mg dose; repeat the test every 24 hours until results are negative.
If it is uncertain whether the patient is opiate free or is undergoing opiate withdrawal following an initial test, repeat the naloxone challenge test with a 1.6-mg IV dose.

Administration

Administer orally or by IM injection.

Do not administer parenteral preparation by IV injection.

Oral Administration

Administer orally; minimize adverse GI effects by taking with food or antacids or after meals.

Patients should take naltrexone as directed and not attempt self-administration of opiates during therapy with the drug. (See Risks Associated with Self-administration of Opiates During Naltrexone Therapy under Cautions.)

IM Administration

IM preparation used in individuals who are able to abstain from alcohol in an outpatient setting and are abstinent when treatment is initiated.

Administer by deep IM injection into the upper outer quadrant of the gluteal muscle every 4 weeks (or once a month); alternate buttocks for subsequent injections.

Administer only with needle and other components of dose pack supplied by manufacturer.

Use aspiration to avoid inadvertent injection into a blood vessel.

Reconstitution

Consult manufacturer's labeling for instructions for using components of dose pack for reconstitution.

Allow dose pack to reach room temperature before reconstituting.

Reconstitute vial containing naltrexone extended-release microspheres with 3.4 mL of diluent; shake vigorously for 1 minute. Use only the diluent supplied by the manufacturer. Administer immediately.

Dosage

Available for oral administration as naltrexone hydrochloride; dosage expressed in terms of the salt.

Available for IM administration as naltrexone.

Adults

Opiate Dependence

Induction of Therapy for Opiate Cessation

Oral

Initiate induction regimen following completion of opiate detoxification and verification that the patient is free of opiates. (See General under Dosage and Administration.)

Initially, 25 mg; if no evidence of withdrawal is present, begin 50 mg daily.

Alternatively, some clinicians have administered 12.5 mg initially, followed by incremental increases of 12.5 mg daily until the usual dosage of 50 mg daily has been achieved.

Maintenance Therapy for Opiate Cessation

Oral

50 mg daily following induction of therapy.

Alternatively, flexible dosing schedules have been suggested in an attempt to improve compliance. Administration of larger doses at longer intervals (e.g., 48–72 hours) may reduce opiate antagonist activity somewhat, but may improve compliance. Single doses >50 mg may increase risk of hepatic injury; weigh possible risks against probable benefits of flexible dosing.

Flexible Naltrexone Hydrochloride Dosing Schedules for Maintenance Therapy for Opiate Cessation

50 mg daily Monday through Friday and 100 mg on Saturday
100 mg every other day
150 mg every third day
100 mg on Monday and Wednesday and 150 mg on Friday
150 mg on Monday and 200 mg on Thursday

Ingestion of the naltrexone dose generally should be observed in a clinic setting or by a responsible family member to ensure compliance, in which case, regimens requiring less frequent visits may be more acceptable to the patient.

Monitor patient compliance by random testing of urine for naltrexone and 6-β-naltrexol or for the presence of opiates.

Optimum duration of maintenance therapy not established; base on individual requirements and response.

In patients who discontinue naltrexone prematurely and then desire to resume therapy following a relapse to opiate abuse, perform urinalysis for the presence of opiates and, if necessary, a naloxone challenge test prior to resuming therapy. If there is evidence of opiate dependence, conduct detoxification prior to reinitiation of naltrexone therapy.

Opiate Detoxification

Oral

Various dosage regimens have been used for rapid or ultrarapid detoxification† of opiate dependence.†

The following regimen of naltrexone, given in conjunction with clonidine to attenuate withdrawal manifestations, has been studied.†

Day of Detoxification Therapy†	Clonidine Hydrochloride†	Naltrexone Hydrochloride†
Day 1†	0.005 mg/kg initially; then titrated according to the severity of withdrawal and the adverse effects induced by clonidine†
Day 2†	Administered every 4 hours to attenuate the withdrawal induced by naltrexone†	Administered every 4 hours; 1 mg initially; then increased in 1-mg increments during the daytime on day 2 †
Day 3†	Administered every 4 hours to attenuate the withdrawal induced by naltrexone; highest mean dosage was 2.3 mg daily on day 3†	Administered every 4 hours; dosage increased in 2-mg increments during the daytime on day 3†
Day 4†	Administered only as needed to reduce signs and symptoms of withdrawal†	10 mg 3 times daily†
Day 5†	Administered only as needed to reduce signs and symptoms of withdrawal†	50 mg once daily†

Alcohol Dependence

Oral

50 mg once daily, following verification that the patient is free of opiates.(See General under Dosage and Administration.)

Optimum duration of therapy not established; safety and efficacy established only in short-term (up to 12 weeks) studies.

IM

380 mg every 4 weeks or once a month following verification that the patient is free of opiates. (See General under Dosage and Administration.)

If a dose is missed, reschedule administration with a health-care professional as soon as possible.

Therapy may be initiated with parenteral preparation; not necessary to initiate therapy with oral naltrexone and then switch to parenteral preparation.