Naltrexone 3.5mg capsules
Requires a prescription from a doctor or prescriber
Derivative of noroxymorphone that is the N-cyclopropylmethyl congener of naloxone.
Genetic variations that may affect drug response
1 known genetic variation may influence how your body responds to Naltrexone 3.5mg capsules.Gene involved: OPRM1
These are known genetic variations. They don't mean the medicine won't work for you — speak to your doctor or a pharmacogenomics specialist for personalised advice. Source: DrugBank (CC BY-NC 4.0).
Official documents, adverse reaction reporting, and safety monitoring
Report a side effect
Submit a Yellow Card report to the MHRA
Official medicine documents
Safety monitoring data
Yellow Card reports
The MHRA Yellow Card scheme collects reports of suspected side effects from healthcare professionals and patients. View the Drug Analysis Profile (iDAP) for real-world adverse reaction data.
View Drug Analysis Profile
Suspected adverse reactions reported for Naltrexone
Browse all iDAP reports
Interactive Drug Analysis Profiles for all medicines
Report a side effect
Submit a Yellow Card report to the MHRA
Data from the MHRA Yellow Card scheme. A reported reaction does not necessarily mean the medicine caused it. Contains public sector information licensed under the Open Government Licence v3.0.
EudraVigilance
The European Medicines Agency (EMA) collects suspected adverse reaction reports from across the EU/EEA through the EudraVigilance system. Search for safety data on this medicine.
View EudraVigilance report
Suspected adverse reactions reported for Naltrexone
About EudraVigilance
Learn about EU pharmacovigilance and safety monitoring
EudraVigilance data is published by the European Medicines Agency (EMA). A suspected adverse reaction is not necessarily caused by the medicine.
1 branded products available
WHO defined daily dose (DDD)
50 mg
Not a recommended dose. The DDD is the assumed average maintenance dose per day for a drug used for its main indication in adults. It is a statistical measure used for research and comparison purposes only.
Source: WHO Collaborating Centre for Drug Statistics Methodology, distributed via NHS dm+d BNF mapping files. Contains public sector information licensed under the Open Government Licence v3.0.
Therapeutically similar medicines
Similarity based on WHO Anatomical Therapeutic Chemical (ATC) classification and NHS BNF section grouping. Source data: NHS dm+d via TRUD (OGL v3.0), WHO ATC/DDD Index.
NHS prescribing volume and spending trends
Clinical guidelines and formulary information
British National Formulary
Naltrexone
Source: British National Formulary, NICE. Joint Formulary Committee. Contains public sector information licensed under the Open Government Licence v3.0.
NICE clinical guidance(8)
Naltrexone for the management of opioid dependence (TA115)
Alcohol-use disorders: diagnosis, assessment and management of harmful drinking (high-risk drinking) and alcohol dependence (CG115)
Gambling-related harms: identification, assessment and management (NG248)
Drug misuse in over 16s: psychosocial interventions (CG51)
Nalmefene for reducing alcohol consumption in people with alcohol dependence (TA325)
Naltrexone–bupropion for managing overweight and obesity (TA494)
Drug misuse in over 16s: opioid detoxification (CG52)
Alcohol-use disorders: diagnosis and management (QS11)
Source: National Institute for Health and Care Excellence (NICE). Contains public sector information licensed under the Open Government Licence v3.0.
Check stock at pharmacies and supply information
Pharmacy stock checkers
Search for this medicine at major UK pharmacy chains. These links open the retailer's own website — results depend on their current online catalogue.
Supply & product information
Official product databases and supply status monitoring
Pharmacy links redirect to the retailer's own search and do not represent real-time stock levels. emc (electronic medicines compendium) is operated by Datapharm Ltd. Shortage information sourced from NHS Specialist Pharmacy Service (SPS), sps.nhs.uk.
Codes for healthcare professionals and prescribing systems
These codes are used by healthcare IT systems and prescribers to identify this medicine.
NHS UK identifiers
Browse tools
SNOMED CT and dm+d codes from NHS TRUD (Technology Reference data Update Distribution), licensed under the Open Government Licence v3.0. BNF codes from NHS Business Services Authority (NHSBSA). ATC codes from the WHO Collaborating Centre for Drug Statistics Methodology (whocc.no).
Active and completed clinical studies from ClinicalTrials.gov
Source: ClinicalTrials.gov, a database of the U.S. National Library of Medicine (NLM), National Institutes of Health (NIH). Data accessed via ClinicalTrials.gov API v2. Trial information is provided for research purposes and does not constitute medical advice.
Pharmacology and chemical data from DrugBank
Key facts
Drug status
Approved
Major interactions
44 found
Half-life
4 hours
Mechanism
Naltrexone is a pure opiate antagonist and has little or no agonist activity.
Food interactions
1 warning
Human targets
4 targets
Data: DrugBank · CC BY-NC 4.0
Pharmacokinetics at a glance
Absorption
5 to 40%
Half-life
4 hours
Protein binding
21%
Volume of distribution
1350 L
Metabolism
Elimination
53%
Clearance
3.5 L
Pharmacokinetic data: DrugBank · CC BY-NC 4.0
Known interactions with other medications. Always consult a healthcare professional.
Showing 50 of 546 interactions
How the body processes this drug — absorption, distribution, metabolism, and elimination
Proteins and enzymes this drug interacts with in the body
PMID:10529478 PMID:12589820 PMID:7891175 PMID:7905839 PMID:7957926 PMID:9689128
Receptor for natural and synthetic opioids including morphine, heroin, DAMGO, fentanyl, etorphine, buprenorphin and methadone .
PMID:10529478 PMID:10836142 PMID:12589820 PMID:19300905 PMID:7891175 PMID:7905839 PMID:7957926 PMID:9689128
Also activated by enkephalin peptides, such as Met-enkephalin or Met-enkephalin-Arg-Phe, with higher affinity for Met-enkephalin-Arg-Phe (By similarity). Agonist binding to the receptor induces coupling to an inactive GDP-bound heterotrimeric G-protein complex and subsequent exchange of GDP for GTP in the G-protein alpha subunit leading to dissociation of the G-protein complex with the free GTP-bound G-protein alpha and the G-protein beta-gamma dimer activating downstream cellular effectors .
PMID:7905839
The agonist- and cell type-specific activity is predominantly coupled to pertussis toxin-sensitive G(i) and G(o) G alpha proteins, GNAI1, GNAI2, GNAI3 and GNAO1 isoforms Alpha-1 and Alpha-2, and to a lesser extent to pertussis toxin-insensitive G alpha proteins GNAZ and GNA15 .
PMID:12068084
They mediate an array of downstream cellular responses, including inhibition of adenylate cyclase activity and both N-type and L-type calcium channels, activation of inward rectifying potassium channels, mitogen-activated protein kinase (MAPK), phospholipase C (PLC), phosphoinositide/protein kinase (PKC), phosphoinositide 3-kinase (PI3K) and regulation of NF-kappa-B (By similarity). Also couples to adenylate cyclase stimulatory G alpha proteins (By similarity).
The selective temporal coupling to G-proteins and subsequent signaling can be regulated by RGSZ proteins, such as RGS9, RGS17 and RGS4 (By similarity). Phosphorylation by members of the GPRK subfamily of Ser/Thr protein kinases and association with beta-arrestins is involved in short-term receptor desensitization (By similarity). Beta-arrestins associate with the GPRK-phosphorylated receptor and uncouple it from the G-protein thus terminating signal transduction (By similarity).
The phosphorylated receptor is internalized through endocytosis via clathrin-coated pits which involves beta-arrestins (By similarity). The activation of the ERK pathway occurs either in a G-protein-dependent or a beta-arrestin-dependent manner and is regulated by agonist-specific receptor phosphorylation (By similarity). Acts as a class A G-protein coupled receptor (GPCR) which dissociates from beta-arrestin at or near the plasma membrane and undergoes rapid recycling (By similarity).
Receptor down-regulation pathways are varying with the agonist and occur dependent or independent of G-protein coupling (By similarity). Endogenous ligands induce rapid desensitization, endocytosis and recycling (By similarity). Heterooligomerization with other GPCRs can modulate agonist binding, signaling and trafficking properties (By similarity)
Signaling leads to the inhibition of adenylate cyclase activity. Inhibits neurotransmitter release by reducing calcium ion currents and increasing potassium ion conductance. Plays a role in the perception of pain.
Plays a role in mediating reduced physical activity upon treatment with synthetic opioids. Plays a role in the regulation of salivation in response to synthetic opioids. May play a role in arousal and regulation of autonomic and neuroendocrine functions
Inhibits neurotransmitter release by reducing calcium ion currents and increasing potassium ion conductance. Plays a role in the perception of pain and in opiate-mediated analgesia. Plays a role in developing analgesic tolerance to morphine
Plays a role in calcium signaling through modulation together with ANK2 of the ITP3R-dependent calcium efflux at the endoplasmic reticulum. Plays a role in several other cell functions including proliferation, survival and death. Originally identified for its ability to bind various psychoactive drugs it is involved in learning processes, memory and mood alteration .
PMID:16472803 PMID:9341151
Necessary for proper mitochondrial axonal transport in motor neurons, in particular the retrograde movement of mitochondria.
Plays a role in protecting cells against oxidative stress-induced cell death via its interaction with RNF112 (By similarity)
Enzymes involved in drug metabolism — important for understanding drug interactions
ATC N02AA56
ATC N07BB04
ATC A08AA62
Chemical identifiers
CAS, UNII, InChI Key and database cross-references
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Chemical identifiers
CAS, UNII, InChI Key and database cross-references
Linked compound data from DrugBank Open Data (CC BY-NC 4.0)
Naltrexone
Additional database identifiers
Drugs Product Database (DPD)
20300
ChemSpider
4514524
BindingDB
60212
ZINC
ZINC000000001773
HUGO Gene Nomenclature Committee (HGNC)
HGNC:8156
GenAtlas
OPRM1
GeneCards
OPRM1
GenBank Gene Database
L25119
GenBank Protein Database
452073
Guide to Pharmacology
319
UniProt Accession
OPRM_HUMAN
HUGO Gene Nomenclature Committee (HGNC)
HGNC:8154
GenAtlas
OPRK1
GeneCards
OPRK1
GenBank Gene Database
U11053
GenBank Protein Database
532060
Guide to Pharmacology
318
UniProt Accession
OPRK_HUMAN
HUGO Gene Nomenclature Committee (HGNC)
HGNC:8153
GenAtlas
OPRD1
GeneCards
OPRD1
GenBank Gene Database
U07882
GenBank Protein Database
27545517
Guide to Pharmacology
317
UniProt Accession
OPRD_HUMAN
HUGO Gene Nomenclature Committee (HGNC)
HGNC:8157
GenAtlas
OPRS1
GeneCards
SIGMAR1
GenBank Gene Database
U75283
GenBank Protein Database
1783387
Guide to Pharmacology
2552
UniProt Accession
SGMR1_HUMAN
HUGO Gene Nomenclature Committee (HGNC)
HGNC:12530
GeneCards
UGT1A1
GenBank Gene Database
M57899
GenBank Protein Database
184473
Guide to Pharmacology
2990
UniProt Accession
UD11_HUMAN
International reference pricing
Reference pricing from DrugBank. Prices are indicative and may not reflect current UK costs.
Source: DrugBank. Used under CC BY-NC 4.0 academic licence for non-commercial purposes.
Patent information
26 active patents, 24 expired
Source: DrugBank · CC BY-NC 4.0. Patent data sourced from national patent offices. Expiry dates may not reflect extensions, regulatory exclusivity periods, or legal challenges.
DrugBank citations
If you use DrugBank data in your research, please cite the following publications: