Anthropometric Measurements as Predictors of Low Birth Weight Among Tanzanian Neonates: A Hospital-Based Study
November 7, 2025
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Brand Name :
Vivitrol
(United States) [Available]Synonyms :
naltrexone
Class :
Opioid Antagonists
Brand Name :
Vivitrol
(United States) [Available]Synonyms :
naltrexone
Class :
Opioid Antagonists
Dosage Forms & StrengthsÂ
TabletÂ
50 mgÂ
Microspheres Â
380 mgÂ
For oral: take 25 mg initially, then observe for one hour, then 50 mg one time a day starting on second day
For Intramuscular: administer 380 mg in gluteal muscle each four weeks for maintenance of abstinence
Off-label:
Some studies have explored the potential effects of naltrexone on cannabis use
Single doses of naltrexone in the range of 12-100 mg have been found to enhance the subjective effects or feelings associated with using cannabis
naltrexone alone may increase the perceived effects of cannabis when taken in certain doses
Daily administration of naltrexone at a dose of 50 mg for three weeks has shown promise in reducing cannabis self-administration and use in individuals not seeking treatment for Cannabis Use Disorder (CUD)
Note:
This indicates that daily use of naltrexone may potentially have a role in reducing cannabis use in some individuals
It's essential to note that the use of naltrexone for cannabis-related issues is not an FDA-approved indication
The primary approved use of naltrexone remains for opioid and alcohol use disorders
More research is needed to fully understand the effectiveness and safety of naltrexone in addressing cannabis use issues
Safety and efficacy not determined Â
Refer to adult dosingÂ
may decrease the opiod agonists therapeutic effect
may affect the absorption of drugs when combined
may affect the absorption of drugs when combined
may affect the absorption of drugs when combined
may affect the absorption of drugs when combined
may affect the absorption of drugs when combined
may affect the absorption of drugs when combined
may affect the absorption of drugs when combined
may affect the absorption of drugs when combined
amoxicillin/omeprazole/rifabutin
may affect the absorption of drugs when combined
may affect the absorption of drugs when combined
it decreases the effect of opioid agonists
it decreases the effect of opioid agonists
it increases the efficacy of opioid agonists
it increases the efficacy of opioid agonists
may decrease the therapeutic effect when combined with opioid agonists
may decrease the therapeutic effect when combined with opioid agonists
may decrease the therapeutic effect when combined with opioid agonists
may decrease the therapeutic effect when combined with opioid agonists
naltrexone: they may increase the CNS depressant effect of CNS Depressants
naltrexone: they may increase the CNS depressant effect of CNS Depressants
naltrexone: they may increase the CNS depressant effect of CNS Depressants
naltrexone: they may increase the CNS depressant effect of CNS Depressants
naltrexone: they may increase the CNS depressant effect of CNS Depressants
may decrease the therapeutic effect
may decrease the therapeutic effect of opioid agonists
may decrease the therapeutic effect of Opioid Agonists
bremelanotide: they may diminish the serum concentration of naltrexone
it may diminish the therapeutic efficacy when combined with castor oil
naltrexone: they may enhance the serum concentration of CYP2D6 Inhibitors
naltrexone: they may enhance the serum concentration of CYP2D6 Inhibitors
naltrexone: they may enhance the serum concentration of CYP2D6 Inhibitors
naltrexone: they may enhance the serum concentration of CYP2D6 Inhibitors
naltrexone: they may enhance the serum concentration of CYP2D6 Inhibitors
when both the drugs are combined, carmustine may decrease the renal secretion of naltrexone and increases the serum level    
Actions and SpectrumÂ
naltrexone binds to opioid receptors, particularly the mu-opioid receptors, as a competitive antagonist. Â
It blocks the effects of exogenous opioids, such as heroin or prescription pain medications, preventing them from producing their usual analgesic effects.Â
naltrexone is effective in the treatment of opioid dependence and alcohol dependence.
Frequency defined Â
<1%Â
EdemaÂ
PhlebitisÂ
TachycardiaÂ
Increased systolic and diastolic blood pressuresÂ
PalpitationÂ
Labored breathingÂ
Opiate withdrawal Â
Nonspecific electrocardiographic (ECG) changesÂ
Liver function abnormalitiesÂ
Hepatocellular injuryÂ
AlopeciaÂ
DyspneaÂ
1-10%Â
Rash (6%)Â
Somnolence (4%)Â
Muscle cramps (8%)Â
Dry mouth (5%)Â
Back pain (6%)Â
Depression (8%)Â
>10%Â
Injection site reaction (69%)Â
Dizziness (13%)Â
Anxiety (12%)Â
Decreased appetite (14%)Â
Upper respiratory tract infection (13%)Â
Insomnia (14%)Â
Arthralgia (12%)Â
Pharyngitis (11%)Â
Diarrhea (13%)Â
Increased creatine phosphokinase (11%)Â
Vomiting (14%)Â
Nausea (33%)Â
Headache (25%)Â
Post marketing ReportsÂ
Hypersensitivity reactionsÂ
Black Box WarningÂ
None
Contraindication/Caution:Â
Contraindication:Â
Caution:Â
Pregnancy consideration:Â
Pregnancy category: N/AÂ
Lactation: It present in human milk Â
Pregnancy Categories:        Â
Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester.Â
Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. Â
Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.Â
Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.Â
Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.Â
Category N: There is no data available for the drug under this category.Â
Pharmacology Â
naltrexone binds to opioid receptors, primarily the mu-opioid receptors, without activating them. Â
naltrexone blocks the effects of exogenous opioids and endogenous opioids that would activate these receptors.Â
PharmacodynamicsÂ
Limited information available Â
PharmacokineticsÂ
Absorption  Â
The bioavailability of naltrexone is approximately 5%. It is rapidly absorbed from the gastrointestinal tract and reaches peak plasma concentrations within 1 to 2 hours. Â
DistributionÂ
naltrexone has a large volume of distribution approximately 1350 L. Â
MetabolismÂ
naltrexone is metabolized in the liver. It undergoes hepatic metabolism through the cytochrome P450 enzyme. Â
Elimination and excretionÂ
naltrexone and its metabolites are excreted through the kidneys.
AdministrationÂ
naltrexone can be administered through different routes, including oral, intramuscular, and subcutaneous routes. Â
It is available in form of tablets, injectables formulations and subcutaneous implant. Â
Patient information leafletÂ
Generic Name: naltrexoneÂ
Why do we use naltrexone?Â
The use of naltrexone as an off-label treatment for Cannabis Use Disorder (CUD) is based on the understanding that naltrexone, as an opioid receptor antagonist, may have an impact on the endocannabinoid system. While the primary FDA-approved use of naltrexone is for the treatment of opioid and alcohol use disorders, researchers have explored its potential effects on cannabis use due to the interaction between the endocannabinoid and opioid systems in the brain.
The endocannabinoid system plays a crucial role in regulating various physiological processes, including mood, pain perception, appetite, and reward pathways. The main receptors of the endocannabinoid system are the CB1 and CB2 receptors. CB1 receptors are primarily found in the brain and are involved in the rewarding effects of substances like cannabis.
naltrexone, as an opioid receptor antagonist, binds to and blocks opioid receptors, which are also present in the brain. Some studies have suggested that the opioid system may interact with the endocannabinoid system, and by blocking opioid receptors, naltrexone may indirectly affect the endocannabinoid system, potentially influencing the subjective effects of cannabis.
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