Naloxone Stats & Data
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DrugBankDescription
Naloxone is an opioid antagonist medication used to block or reverse the effects of opioid drugs, particularly within the setting of drug overdoses which are rapidly becoming a leading cause of death worldwide. More specifically, naloxone has a high affinity for μ-opioid receptors, where it acts as an inverse agonist, causing the rapid removal of any other drugs bound to these receptors. When taken in large quantities, opioid medications such as morphine, hydromorphone, methadone, heroin, or fentanyl are capable of causing life-threatening symptoms such as respiratory depression, reduced heart rate, slurred speech, drowsiness, and constricted pupils. If untreated, this can progress to vomiting, absent pulse and breathing, loss of consciousness, and even death. Naloxone is indicated for the rapid reversal of these symptoms of central nervous system depression in opioid overdose. It's important to note that naloxone only works on opioid receptors within the body, and is therefore not capable of reversing the effects of non-opioid medications such as stimulants like methamphetamine or cocaine, or benzodiazepines like lorazepam or diazepam. Also known as the brand name product Narcan, naloxone is currently available by intramuscular (IM) or subcutaneous (SubQ) injection, nasal spray, or intravenous (IV) infusion.
Mechanism of Action
Naloxone is a competitive inhibitor of the µ-opioid receptor. Naloxone antagonizes the action of opioids, reversing their effects. If a patient has not taken opioids, naloxone does not have a significant effect on patients.
Pharmacodynamics
Naloxone is an opioid receptor antagonist indicated in the reversal of opioid overdoses. Naloxone has a shorter duration of action than opioids and multiple doses may be required. The therapeutic window of naloxone is wide, as it has no effect if a patient has not taken opioids. Patients treated with naloxone may experience opioid withdrawal and a person administering naloxone should be aware that reversal of opioid overdoses may not resolve all the symptoms a patient is experiencing if other drugs are involved.
Metabolism
Naloxone primarily undergoes glucuronidation to form naloxone-3-glucuronide. Naloxone is also N-dealkylated to noroxymorphone or undergoes 6-keto reduction to naloxol.
Absorption
An intranasal dose of naloxone is 42-47% bioavailable. An 8 mg dose of nasal naloxone reaches a Cmax of 12.3-12.8 ng/mL, with a Tmax of 0.25 hours, and an AUC of 16.7-19.0 h\*ng/mL. A 0.4 mg intramuscular dose reaches a Cmax of 0.876-0.910 ng/mL, with a Tmax of 0.25 hours, and an AUC of 1.94-1.95 h\*ng/mL. A 2 mg intravenous dose reaches a Cmax of 26.2 ng/mL with an AUC of 12.8 h\*ng/mL.
Toxicity
If a patient has not taken opioids, naloxone does not have a significant effect on patients. The oral LD50 in mice and rats is >1 g/kg. The intraperitoneal LD50 is 80 mg/kg in mice and 239 mg/kg in rats. The subcutaneous LD50 is 286 mg/kg in mice and 500 mg/kg in rats.
Indication
Naloxone nasal sprays are indicated for the emergency treatment of an opioid overdose or suspected opioid overdose. Intramuscular, intravenous, and subcutaneous injections are indicated for complete or partial reversal of opioid depression, diagnosis of known or suspected opioid overdose, and as an adjunct therapy in the treatment of septic shock. Sublingual tablets and films are formulated with buprenorphine for the treatment of opioid dependence. Naloxone is also formulated with pentazocine as an oral tablet for severe pain. Naloxone has been used off-label for the treatment of neuraxial opioid-induced pruritus.
Half-life
The mean half life of naloxone hydrochloride is 1.8-2.7 hours intranasally, 1.4 hours intramuscularly, and 1.2 hours intravenously. In neonates, the mean half life is 3.1 ± 0.5 hours.
Protein Binding
Naloxone is approximately 45% bound to albumin, but there is significant binding to other proteins.
Elimination
After oral or intravenous administration, naloxone is 25-40% eliminated in the urine within 6 hours, 50% in 24 hours, and 60-70% in 72 hours. The metabolites naloxone-3-glucuronide, noroxymorphone, and naloxol are all detected in the urine.
Volume of Distribution
The volume of distribution of naloxone is 200 L. Naloxone distributes into tissues rapidly. It can also cross the placenta and blood-brain barrier.
Effect Profile
Curated + 46 ReportsStrong euphoria, itching/nausea, and sedation with mild pain relief
Tolerance & Pharmacokinetics
drugs.wikiTolerance Decay
Experience Report Analysis
ErowidDemographics
Gender Distribution
Age Distribution
Reports Over Time
Effect Analysis
ErowidEffects aggregated from 46 experience reports (46 Erowid)
Effect Sentiment Distribution
Confidence Distribution
Positive Effects 10
Adverse Effects 5
Dose-Response Correlation
How effect frequency changes across dose levels
View data table
| Effect | Common (n=13) |
|---|---|
| Euphoria | 61.5% |
| Nausea | 30.8% |
| Empathy | 30.8% |
| Stimulation | 30.8% |
| Sedation | 23.1% |
| Anxiety Suppression | 15.4% |
| Dissociation | 15.4% |
| Music Enhancement | 15.4% |
| Tactile Enhancement | 15.4% |
| Sweating | 15.4% |
Dose–Effect Mapping
Experience ReportsHow reported effects shift across dose tiers, based on 46 experience reports.
Limited tier coverage — most reports fall within the Common range. Effects at other dose levels may not be represented.
| Effect | Common (n=13) | |
|---|---|---|
| euphoria | ||
| nausea | ||
| empathy | ||
| stimulation | ||
| sedation | ||
| anxiety suppression | ||
| dissociation | ||
| music enhancement | ||
| tactile enhancement | ||
| sweating |
Dosage Distribution
Dose distribution from experience reports
Real-World Dose Distribution
62K DosesFrom 102 individual dose entries
Sublingual (n=64)
Oral (n=10)
Insufflated (n=7)
Intravenous (n=7)
Common Combinations
Most co-occurring substances in experience reports
Form / Preparation
Most common forms and preparations reported
Body-Weight Dosing
Dose relative to body weight from reports with weight data
Sublingual
Unknown
Redose Patterns
Redosing behavior across 34 reports