Drug reference

Naltrexone

Opioid Analgesic · Antagonist

Opioid AnalgesicAntagonist

CDSCO approvedSchedule H

EXCRETION

—

not curated

INTERACTIONS

12 major

incl. contraindicated

PREGNANCY

—

not curated

Top interactionssee all 12 →

NalmefeneContraindicatedTextbookG&G 14e · p527, p528, p529
NaloxoneContraindicatedTextbookG&G 14e · p527, p528, p529
AcetaminophenSevereTextbookHarrison 22e · p98-99
AlprazolamSevereTextbookG&G 14e

Mechanism

Naltrexone is an opioid receptor antagonist. While the specific mechanism of action for Naltrexone is not detailed in the provided text, related drugs in the same class (opioid receptor antagonists) function to counteract the effects of opioids.

Indications

opioid use disorderalcohol use disorderadjunct for weight management (in combination with bupropion)management of schizophrenia (in combination with olanzapine)opioid use disorder (after opioid detoxification)Opioid use disorder managementAlcohol use disorder managementPrevent relapse of alcoholismreduce alcohol cravingreduce number of drinking daysreduce chances of resumed heavy drinkingadjuvant in comprehensive treatment programmes for alcohol dependent subjects (after withdrawal and motivation)opioid blockade therapy of postaddictsprevention of relapse of heavy drinking

Dosing

Adult: midazolam p. 356 by subcutaneous infusion using a continuous infusion device see below. Dry mouth Dry mouth may be relieved by good mouth care and measures such as chewing sugar-free gum, sucking ice or pineapple chunks, or the use of artiﬁcial saliva,dry mouth associated with candidiasis can be treated by oral preparations of nystatin p. 1284 or miconazole p. 876, alternatively, ﬂuconazole p.…

Pharmacokinetics

Duration

Antagonistic effects: ~24 h (after moderate oral doses); up to 48 h (with 100 mg oral doses)

Half-life

3 h (parent drug); 13 h (6-naltrexol metabolite)

Bioavailability

More effective by the oral route than naloxone

Protein binding

21%

Metabolism

Metabolized to 6-naltrexol

Excretion

Contraindications

hepatitis
liver failure (black-box warning: excessive doses cause hepatocellular injury)
liver failure
acute hepatitis
concomitant use with opioid analgesics (can cause withdrawal in opioid-dependent patients)
opioid dependence (not for use in opioid-dependent patients without prior opioid detoxification)
Used before opioid detoxification
Presence of opioids

Side effects

Common

nausea (most common)headachedizzinessanxietyinsomniaNauseanausea (common)

Serious

precipitation of withdrawal syndrome (in opioid-dependent individuals)
hepatocellular injury (with excessive doses)
hepatotoxicity (with oral doses exceeding 300 mg)
Precipitates opioid withdrawal
high doses can cause hepatotoxicity
very high doses have caused unpleasant feelings in some individuals

Drug interactions

Nalmefene

Contraindicated

Textbook

Blocks the analgesic effects of opioid analgesics. Can precipitate severe withdrawal symptoms in an opioid-dependent patient.

Naltrexone is contraindicated in patients taking opioids concurrently. If opioid analgesics are needed for pain management, higher doses may be required and should be administered under strict medical supervision after considering the risks.

Source: G&G 14e · p527, p528, p529

Naloxone

Contraindicated

Textbook

Blocks the analgesic effects of opioid analgesics. Can precipitate severe withdrawal symptoms in an opioid-dependent patient.

Source: G&G 14e · p527, p528, p529

Acetaminophen

Severe

Textbook

Acetaminophen-related hepatotoxicity, a significant cause for liver failure.

Many practitioners have moved away from opioid-acetaminophen combination analgesics to avoid the risk of excessive acetaminophen exposure.

Source: Harrison 22e · p98-99

Alprazolam

Severe

Textbook

Increased rates of accidental overdose and death.

Caution is advised, especially for patients with a history of drug abuse.

Source: G&G 14e

Barbiturates

Severe

Textbook

Exaggerated CNS depression.

Source: KDT 7e · p401

Benzodiazepines

Severe

Textbook

Marked depression of respiration, cardiac contractility, and blood pressure.

Carefully monitor respiratory and cardiovascular functions when co-administering benzodiazepines with opioids due to increased risk of severe depression of vital signs.

Source: KDT 7e · p383

Chloral Hydrate

Severe

Textbook

Increased rates of accidental overdose and death.

Caution is advised, especially for patients with a history of drug abuse.

Source: G&G 14e

Chlordiazepoxide Hydrochloride

Severe

Textbook

Increased rates of accidental overdose and death.

Caution is advised, especially for patients with a history of drug abuse.