generation run 2026-05-08
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16 searches — query, source, results, what was kept and why
| # | source | query | seen | kept | rationale |
|---|---|---|---|---|---|
| 1 | PubChem | carfentanil | 1 | 1 | — |
| 2 | PubMed | carfentanil pharmacology opioid receptor binding | 15 | 7 | — |
| 3 | OpenAlex | carfentanil opioid pharmacology | 15 | 0 | — |
| 4 | WebFetch | — | 1 | 2 | — |
| 5 | PubMed | carfentanil naloxone reversal respiratory depression treatment | 12 | 5 | — |
| 6 | WebSearch | carfentanil SMILES CAS number 59708-52-0 melting point physical properties | 10 | 1 | — |
| 7 | PubMed | cytochrome P450 CYP3A4 carfentanil oxidative metabolism identification | 1 | 1 | — |
| 8 | OpenAlex | carfentanil overdose death illicit fentanyl analog | 10 | 3 | — |
| 9 | PMC/PubMed | — | 1 | 3 | — |
| 10 | WebSearch | carfentanil legal status UK Canada Australia EU controlled substance 2026 | 10 | 3 | — |
| 11 | ClinicalTrials.gov | carfentanil | 10 | 0 | — |
| 12 | PubMed | carfentanil fentanyl analog illicit drug supply forensic | 5 | 4 | — |
| 13 | WebFetch | — | 1 | 4 | — |
| 14 | WebSearch | carfentanil DEA Schedule I scheduling history 2016 Wildnil veterinary | 10 | 3 | — |
| 15 | PubMed | carfentanil chemical weapon incapacitating agent Moscow theater | 1 | 1 | — |
| 16 | PubMed | carfentanil overdose toxicology death case report | 1 | 1 | — |
84 claims by section — every cited sentence, checked against its source
safety20 · 16 ok
Concurrent CNS depressant use — synergistic respiratory depression; the leading cause of carfentanil-associated death is polydrug toxicitysupported
156 of 160 classified as mixed drug toxicity or carfentanil overdose. bkab079
Postmortem blood concentrations in single-drug deaths range from <0.2 to 0.73 ng/mL, overlapping substantially with concentrations in surviving impaired individualspartially supported
Postmortem blood carfentanil concentrations ranged from <0.2 to 0.73 ng/mL in cases listed as sole cause of death. bky054
Postmortem blood concentrations in single-drug deaths range from <0.2 to 0.73 ng/mL, overlapping substantially with concentrations in surviving impaired individualssupported
In 66 cases, blood concentrations of carfentanil ranged from <0.04 to 2.1 ng/mL. Decreased levels of consciousness commonly reported. bkac039
Bradycardia is a consistent finding alongside respiratory depression in rat challenge modelssupported
Lead vaccine protective against carfentanil-induced antinociception, respiratory depression, and bradycardia identified. acsptsci.1c00260
Dose-dependent heart rate decreases occur even at conventional [¹¹C]carfentanil PET tracer doses exceeding 100 ng/kg IV in anesthetized rats, accompanied by increased PCO₂ (a marker of respiratory depression)supported
Significant dose-dependent CO2 increases and heart rate decreases observed in anesthetized rats at conventional tracer dose range (>100 ng/kg IV). s41598-024-66144-4
Cardiac arrest is a common cause of death in overdose modeling.supported
Carfentanil induced more cardiac arrest events and was more difficult to reverse than fentanyl. cpt.2696
Standard GC-MS also fails: in Miami-Dade County, 104 of 134 carfentanil-positive postmortem cases were initially missed by conventional GC-MS. LC-MS/MS is required for reliable detection and quantitationsupported
Carfentanil detected in 134 postmortem cases in Miami-Dade 2016; 104 initially missed by GC-MS. bkx041
Claim in safety — not_supportednot supportedworking →
Claim in safety — not_supportednot supportedworking →
Claim in safety — inconclusiveinconclusiveworking →
Carfentanil's confirmed β-arrestin-biased signaling is associated with enhanced receptor desensitization and potentially faster tolerance development compared to G-protein-biased agonists such as morphine.partially supported
Carfentanil established as beta-arrestin-biased agonist at mu-opioid receptor. bph.16084
The majority of carfentanil overdose deaths in forensic series involve polydrug toxicitysupported
156 of 160 classified as mixed drug toxicity or carfentanil overdose. bkab079
Carfentanil's primary metabolism via CYP3A5/CYP3A4 creates predictable interaction liabilities:supported
CYP3A5 is primary enzyme for norcarfentanil (M1) formation, followed by CYP3A4. j.toxlet.2021.02.017
Carfentanil-stabilized μOR conformations show 10–100-fold reduced sensitivity to naloxone displacementsupported
Naloxone and nalmefene show 10-100x higher IC50-values against CAR vs other opioids. s00204-025-04048-6
Nalmefene demonstrates superior reversal characteristics in PK-PD modeling, attributable to higher MOR affinity and a longer elimination half-lifesupported
Intranasal nalmefene resulted in large clinically meaningful reductions in cardiac arrest vs intranasal naloxone. j.dadr.2024.100268
Claim in safety — inconclusiveinconclusiveworking →
Naltrexone shows approximately 65-fold greater potency than naloxone against carfentanil-occupied μOR, though it is not currently used in emergency reversal settingssupported
Naltrexone ~65x higher potency to inhibit CAR vs naloxone. s00204-025-04048-6
Diprenorphine (veterinary reversal agent) and naloxone are both less potent at reversing carfentanil than at reversing equivalent heroin doses in rats.supported
Both naloxone and diprenorphine less potent at reversing carfentanil effects vs equivalent heroin dose. j.neuropharm.2025.110601
CYP3A4/3A5 inhibitor co-administration — expected increase in carfentanil plasma concentrationssupported
CYP3A5 is primary enzyme for norcarfentanil (M1) formation, followed by CYP3A4. j.toxlet.2021.02.017
Cardiovascular disease — bradycardia is a documented carfentanil effect and may compound pre-existing cardiac conduction abnormalitiessupported
Lead vaccine protective against carfentanil-induced antinociception, respiratory depression, and bradycardia identified. acsptsci.1c00260
pharmacology18 · 17 ok
Functional potency is sub-nanomolar: the EC₅₀ for MOR activation is 0.0049 nMsupported
EC50 0.0051 vs 0.0049 nM acsmedchemlett.9b00404
In cAMP inhibition assays using HEK-293 cells stably expressing human μOR, carfentanil is approximately 85-fold more potent than fentanyl and 620-fold more potent than morphinesupported
Potency to inhibit cAMP ~85x higher than fentanyl and ~620x higher than morphine. s00204-025-04048-6
At equivalent receptor occupancy (EC₅₀-normalized), carfentanil is approximately 8-fold more efficient than morphine, fentanyl, or remifentanil in inhibiting cAMP — indicating that carfentanil stabilizes unique μOR conformations that are ultra-efficient in coupling to G-protein signaling.supported
µOR bind CAR with ~10-times higher affinity than fentanyl or remifentanil... Potency to inhibit cAMP ~85x higher than fentanyl and ~620x higher than morphine. s00204-025-04048-6
Carfentanil exhibits β-arrestin-biased agonism at the μOR, recruiting β-arrestin more efficiently relative to G-protein activation than other fentanyl analogssupported
Carfentanil established as beta-arrestin-biased agonist at mu-opioid receptor. bph.16084
Quantitative binding kinetics studies demonstrate substantially slower dissociation from the μOR compared to nine other fentanyl analogs testedsupported
Carfentanil has substantially slower dissociation kinetics from the opioid receptor compared with nine other fentanyls. cpt.2696
Among synthetic opioids studied to date, only protonitazene (a novel nitazene-class compound) shows slower dissociation than carfentanilsupported
Protonitazene dissociates slower than carfentanil; its displacement requires fourfold higher antagonist concentrations. 2026.04.14.718203
Naltrexone, by contrast, demonstrates approximately 65-fold higher potency than naloxone at displacing carfentanil-stabilized conformations.supported
Naltrexone ~65x higher potency to inhibit CAR vs naloxone. s00204-025-04048-6
The compound is described as MOR-preferring based on its established role as the gold-standard PET radiotracer for selective MOR imaging.supported
Candidates o-18F-1 and p-18F-2 showed optimal brain uptake and high MOR-specific binding. acs.jmedchem.4c02287
The compound is described as MOR-preferring based on its established role as the gold-standard PET radiotracer for selective MOR imaging.supported
[11C]carfentanil ([11C]Caf) is the mu-preferring agonist radiotracer that has largely supplanted [11C]diprenorphine in MOR research. molecules24224190
The human serum half-life is approximately 5.7 hours, determined from in vitro human serum incubation studiessupported
Carfentanil serum half-life approximately 5.7 hours. acsmedchemlett.9b00404
This is notably longer than fentanyl's half-life of approximately 3.7 hours and has direct implications for renarcotization risk — carfentanil's pharmacological duration significantly outlasts naloxone's elimination half-life of approximately 33 minutes.supported
Naloxone elimination half-life ~33 min... Synthetic opioids including fentanyl, carfentanil, and nitazene superagonists have contributed to exponential growth in opioid deaths. ajplung.00314.2024
The primary metabolic pathway involves CYP3A5 (principal enzyme), with CYP3A4 as the second most active isoform, and secondary contributions from CYP2C8 and CYP2C9supported
CYP3A5 is primary enzyme for norcarfentanil (M1) formation, followed by CYP3A4. CYP2C8, CYP2C9 also contribute. j.toxlet.2021.02.017
Claim in pharmacology — inconclusiveinconclusiveworking →
A second metabolite (M2/M0), formed by hydroxylation, retains comparable MOR activity to parent carfentanil (EC₅₀ = 0.0051 nM vs. 0.0049 nM for parent)supported
a major metabolite (M2) showed comparable MOR activity to the parent opioid (EC50 0.0051 vs 0.0049 nM). acsmedchemlett.9b00404
A second metabolite (M2/M0), formed by hydroxylation, retains comparable MOR activity to parent carfentanil (EC₅₀ = 0.0051 nM vs. 0.0049 nM for parent)supported
active metabolite M0 (12% of total)... M0 has comparable MOR activity to carfentanil. j.toxlet.2022.07.006
Phase II metabolism involves glucuronide and sulfate conjugation.supported
phase II reactions (glucuronide/sulfate conjugation) fphar.2019.00238
PK-PD modeling relies on interspecies allometric scaling.supported
Due to lack of published carfentanil data in humans, interspecies allometric scaling used to predict carfentanil PK in humans. psp4.13215
In controlled research settings, [¹¹C]carfentanil is administered intravenously at nanogram-per-kilogram tracer doses for PET imaging.supported
MOR-selective radioligand [11C]carfentanil used to measure whole-body MOR distribution in 13 healthy humans. jnumed.124.269413
pharmacokinetic-detail10 · 10 ok
PK-PD modeling suggests that 10 mg intramuscular naloxone provides more sustained reversal than standard 2 mg dosing.supported
Higher dose naloxone (10 mg) more effective than 2 mg for carfentanil reversal. Second dose of 10 mg at 60 min expedited recovery and delayed renarcotization. psp4.13215
<div class="compact-kv"> <table> <tbody> <tr><td>Human serum half-life (in vitro)</td><td>~5.7 hours</td></tr> <tr><td>Fentanyl half-life (comparator)</td><td>~3.7 hours</td></tr> <tr><td>Primary CYP enzymes</td><td>CYP3A5 > CYP3A4 >> CYP2C8, CYP2C9</td></tr> <tr><td>Major metabolite</td><td>Norcarfentanil (M1; ~40% in HLMs; minimal MOR activity)</td></tr> <tr><td>Active metabolite</td><td>M2/M0 (hydroxylated; EC₅₀ = 0.0051 nM; ~12% abundance)</td></tr> <tr><td>Phase II</td><td>Glucuronide and sulfate conjugation</td></tr> <tr><td>T_max, C_max, V_d, protein binding</td><td>Not characterized in humans</td></tr> <tr><td>Bioavailability by route</td><td>Not characterized in humans</td></tr> <tr><td>PK-PD modeling basis</td><td>Interspecies allometric scaling</td></tr> </tbody> </table> </div>supported
Carfentanil serum half-life approximately 5.7 hours... a major metabolite (M2) showed comparable MOR activity to the parent opioid (EC50 0.0051 vs 0.0049 nM). acsmedchemlett.9b00404
<div class="compact-kv"> <table> <tbody> <tr><td>Human serum half-life (in vitro)</td><td>~5.7 hours</td></tr> <tr><td>Fentanyl half-life (comparator)</td><td>~3.7 hours</td></tr> <tr><td>Primary CYP enzymes</td><td>CYP3A5 > CYP3A4 >> CYP2C8, CYP2C9</td></tr> <tr><td>Major metabolite</td><td>Norcarfentanil (M1; ~40% in HLMs; minimal MOR activity)</td></tr> <tr><td>Active metabolite</td><td>M2/M0 (hydroxylated; EC₅₀ = 0.0051 nM; ~12% abundance)</td></tr> <tr><td>Phase II</td><td>Glucuronide and sulfate conjugation</td></tr> <tr><td>T_max, C_max, V_d, protein binding</td><td>Not characterized in humans</td></tr> <tr><td>Bioavailability by route</td><td>Not characterized in humans</td></tr> <tr><td>PK-PD modeling basis</td><td>Interspecies allometric scaling</td></tr> </tbody> </table> </div>supported
Carfentanil serum half-life approximately 5.7 hours... a major metabolite (M2) showed comparable MOR activity to the parent opioid (EC50 0.0051 vs 0.0049 nM). acsmedchemlett.9b00404
<div class="compact-kv"> <table> <tbody> <tr><td>Human serum half-life (in vitro)</td><td>~5.7 hours</td></tr> <tr><td>Fentanyl half-life (comparator)</td><td>~3.7 hours</td></tr> <tr><td>Primary CYP enzymes</td><td>CYP3A5 > CYP3A4 >> CYP2C8, CYP2C9</td></tr> <tr><td>Major metabolite</td><td>Norcarfentanil (M1; ~40% in HLMs; minimal MOR activity)</td></tr> <tr><td>Active metabolite</td><td>M2/M0 (hydroxylated; EC₅₀ = 0.0051 nM; ~12% abundance)</td></tr> <tr><td>Phase II</td><td>Glucuronide and sulfate conjugation</td></tr> <tr><td>T_max, C_max, V_d, protein binding</td><td>Not characterized in humans</td></tr> <tr><td>Bioavailability by route</td><td>Not characterized in humans</td></tr> <tr><td>PK-PD modeling basis</td><td>Interspecies allometric scaling</td></tr> </tbody> </table> </div>supported
active metabolite M0 (12% of total)... CYP3A5 highest activity toward M1, followed by CYP3A4 and CYP2C8. M0 has comparable MOR activity to carfentanil. j.toxlet.2022.07.006
Three dedicated in vitro studies characterize carfentanil's biotransformation pathways.supported
The primary metabolites of carfentanil, generated from human liver microsomes, were structurally confirmed through chemical synthesis. acsmedchemlett.9b00404
Three dedicated in vitro studies characterize carfentanil's biotransformation pathways.supported
Carfentanil is metabolized to norcarfentanil (M1), active metabolite M0 (12% of total), and other metabolites in human liver microsomes. j.toxlet.2022.07.006
It accounts for approximately 40% of total metabolite formation in human liver microsomes and possesses minimal MOR activity. M2/M0 is formed by hydroxylation of the parent compound and is the most pharmacologically significant metabolite: its MOR activation EC₅₀ (0.0051 nM) is essentially equivalent to parent carfentanil (0.0049 nM)partially supported
a major metabolite (M2) showed comparable MOR activity to the parent opioid (EC50 0.0051 vs 0.0049 nM). acsmedchemlett.9b00404
Glucuronide and sulfate conjugation reactions have been predicted for carfentanil and its Phase I metabolites, consistent with the general metabolic disposition of anilidopiperidine opioids.supported
phase II reactions (glucuronide/sulfate conjugation) fphar.2019.00238
The highly potent M13 metabolite is primarily formed by CYP2C9 (with CYP2C8 as secondary contributor).supported
Highly potent M13 metabolite primarily formed by CYP2C9. CYP2C8, CYP2C9 also contribute. j.toxlet.2021.02.017
The 5.7-hour in vitro serum half-life of carfentanil significantly exceeds naloxone's elimination half-life of approximately 33 minutessupported
Carfentanil serum half-life approximately 5.7 hours. acsmedchemlett.9b00404
summary10 · 10 ok
Approximately 100-fold more potent than fentanyl and 10,000-fold more potent than morphine for analgesia, carfentanil occupies the extreme end of the opioid potency spectrumsupported
Potency of carfentanil is ~10,000 times greater than morphine and 100 times greater than fentanyl. bkx037
Approximately 100-fold more potent than fentanyl and 10,000-fold more potent than morphine for analgesia, carfentanil occupies the extreme end of the opioid potency spectrumpartially supported
Carfentanil estimated to be 10,000 times more potent than morphine. mmwr.mm6643e1
Its research significance is dual: as [¹¹C]carfentanil, it serves as the gold-standard PET radiotracer for μ-opioid receptor imaging in human neuroscience; as an illicit adulterant, it precipitated a public health crisis beginning in 2016 when it appeared in the North American heroin supplypartially supported
[11C]carfentanil ([11C]Caf) is the mu-preferring agonist radiotracer that has largely supplanted [11C]diprenorphine in MOR research. molecules24224190
Its research significance is dual: as [¹¹C]carfentanil, it serves as the gold-standard PET radiotracer for μ-opioid receptor imaging in human neuroscience; as an illicit adulterant, it precipitated a public health crisis beginning in 2016 when it appeared in the North American heroin supplypartially supported
Fentanyl analogs present in >10% of opioid overdose deaths in four states; carfentanil identified most frequently. mmwr.mm6643e1
Carfentanil is a full agonist at the μ-opioid receptor (MOR) with sub-nanomolar functional potency (EC₅₀ = 0.0049 nM for MOR activation)supported
a major metabolite (M2) showed comparable MOR activity to the parent opioid (EC50 0.0051 vs 0.0049 nM) acsmedchemlett.9b00404
It exhibits β-arrestin-biased signaling and stabilizes unique μOR conformations that are approximately 8-fold more efficient in inhibiting cAMP than equivalent receptor occupancy by morphine or fentanylpartially supported
Carfentanil established as beta-arrestin-biased agonist at mu-opioid receptor. bph.16084
It exhibits β-arrestin-biased signaling and stabilizes unique μOR conformations that are approximately 8-fold more efficient in inhibiting cAMP than equivalent receptor occupancy by morphine or fentanylpartially supported
Potency to inhibit cAMP ~85x higher than fentanyl and ~620x higher than morphine. s00204-025-04048-6
Receptor dissociation is substantially slower than other fentanyl analogs, contributing to prolonged pharmacological action and difficulty of antagonist reversal.supported
Carfentanil has substantially slower dissociation kinetics from the opioid receptor compared with nine other fentanyls. cpt.2696
An in vitro human serum half-life of approximately 5.7 hours, combined with an active metabolite of comparable potency, suggests duration significantly exceeding that of fentanyl.supported
Carfentanil serum half-life approximately 5.7 hours... a major metabolite (M2) showed comparable MOR activity to the parent opioid (EC50 0.0051 vs 0.0049 nM). acsmedchemlett.9b00404
Standard naloxone dosing (2–4 mg intranasal) is potentially inadequate for reversal; carfentanil-stabilized μOR conformations show 10–100-fold reduced sensitivity to naloxone compared to other opioidssupported
Naloxone and nalmefene show 10-100x higher IC50-values against CAR vs other opioids. s00204-025-04048-6
comparative-pharmacology9 · 8 ok
PK-PD modeling demonstrates that standard 2 mg and 4 mg intranasal naloxone formulations produce unacceptable cardiac arrest rates for carfentanil overdose.supported
Carfentanil induced more cardiac arrest events and was more difficult to reverse than fentanyl. cpt.2696
PK-PD modeling demonstrates that standard 2 mg and 4 mg intranasal naloxone formulations produce unacceptable cardiac arrest rates for carfentanil overdose.supported
Naloxone tools used by first responders can result in unacceptable loss of life following carfentanil overdose. j.dadr.2024.100268
PK-PD modeling demonstrates that standard 2 mg and 4 mg intranasal naloxone formulations produce unacceptable cardiac arrest rates for carfentanil overdose.supported
FDA translational model applied to evaluate reversal of carfentanil-induced respiratory depression by intranasal nalmefene vs naloxone. cpt.3527
The veterinary and public health literature widely reports carfentanil as approximately 100-fold more potent than fentanyl and approximately 10,000-fold more potent than morphine for analgesia.supported
Potency of carfentanil is ~10,000 times greater than morphine and 100 times greater than fentanyl. bkx037
The potency rank order for ventilatory depression is: 3-methylfentanyl > carfentanil > fentanyl > heroin.supported
Rank order of potency: 3-methylfentanyl > carfentanil > fentanyl > heroin. jpet.123.002032
Signaling efficiency: At equivalent receptor occupancy, carfentanil inhibits cAMP approximately 8-fold more efficiently than morphine, fentanyl, or remifentanil — implying that carfentanil stabilizes unique, ultra-efficient receptor conformationssupported
µOR bind CAR with ~10-times higher affinity than fentanyl or remifentanil... Potency to inhibit cAMP ~85x higher than fentanyl and ~620x higher than morphine. s00204-025-04048-6
Both naloxone and diprenorphine are less potent at reversing carfentanil effects than at reversing equivalent doses of heroin in rat modelssupported
Both naloxone and diprenorphine less potent at reversing carfentanil effects vs equivalent heroin dose. j.neuropharm.2025.110601
Claim in comparative-pharmacology — inconclusiveinconclusiveworking →
Carfentanil's in vitro human serum half-life of approximately 5.7 hours exceeds fentanyl's half-life of approximately 3.7 hourssupported
Carfentanil serum half-life approximately 5.7 hours. acsmedchemlett.9b00404
neuroscience5 · 5 ok
Active metabolite contribution: What proportion of carfentanil's clinical duration and overdose lethality is attributable to the M2/M0 metabolite versus parent compound? No in vivo human data exist to partition these contributions.supported
Carfentanil is metabolized to norcarfentanil (M1), active metabolite M0 (12% of total)... M0 has comparable MOR activity to carfentanil. j.toxlet.2022.07.006
Carfentanil's sub-nanomolar MOR potency (EC₅₀ = 0.0049 nM) implies near-maximal receptor engagement at vanishingly small concentrations, producing reward signaling of extreme intensity.supported
EC50 0.0051 vs 0.0049 nM acsmedchemlett.9b00404
Carfentanil's analgesic potency — approximately 10,000-fold greater than morphine — reflects both high receptor affinity and the ultra-efficient G-protein coupling described in functional assays.supported
Potency of carfentanil is ~10,000 times greater than morphine and 100 times greater than fentanyl. bkx037
Carfentanil's β-arrestin-biased signaling may potentiate respiratory depression through mechanisms distinct from G-protein-mediated effects, though the specific contribution of biased signaling to respiratory arrest has not been isolated experimentally for carfentanilsupported
Carfentanil established as beta-arrestin-biased agonist at mu-opioid receptor. bph.16084
Changes in BP_ND during experimental paradigms (pain, social rejection, placebo analgesia, exercise, addiction) serve as an indirect measure of endogenous opioid releasesupported
Both tracers are displaceable by endogenous opioid peptides, serving in competition-binding models. Many clinical PET studies with [11C]Caf affirm endogenous opioid release in response to painful stimuli. molecules24224190
clinical-evidence4 · 4 ok
[¹¹C]Carfentanil — carfentanil labeled with carbon-11 — is extensively used as a PET radiotracer for μ-opioid receptor imaging in human neuroimaging researchsupported
[11C]carfentanil ([11C]Caf) is the mu-preferring agonist radiotracer that has largely supplanted [11C]diprenorphine in MOR research. Many clinical PET studies with [11C]Caf... molecules24224190
The first in-human whole-body [¹¹C]carfentanil PET study was reported by Dubroff et al. (2025), imaging MOR distribution across 13 healthy human subjects and confirming feasibility for normative receptor mappingsupported
MOR-selective radioligand [11C]carfentanil used to measure whole-body MOR distribution in 13 healthy humans. jnumed.124.269413
Methocinnamox (MCAM): A novel long-duration μOR antagonist demonstrating sustained reversal of carfentanil-induced hypoventilation in rats, with longer protection windows than naloxonesupported
MCAM effectively reversed and prevented hypoventilation from carfentanil with long duration of action. jpet.123.002032
Monoclonal antibodies: Engineered human-antibody fragments with fentanyl pan-specificity capable of reversing carfentanil-induced respiratory depression in mice. In vitro biophysical profiling of anti-carfentanil monoclonal antibodies predicts in vivo efficacysupported
Two of five anti-carfentanil mAbs significantly reversed carfentanil-induced respiratory depression in mice. j.bbrc.2025.151995
receptor-pharmacology4 · 4 ok
Carfentanil binds the human μ-opioid receptor with approximately 10-fold higher affinity than fentanyl or remifentanil and approximately 70-fold higher affinity than morphine, as determined in HEK-293 cells stably expressing human μORsupported
µOR bind CAR with ~10-times higher affinity than fentanyl or remifentanil and ~70-times higher affinity than morphine. s00204-025-04048-6
An independent determination using a MOR activation assay yielded an EC₅₀ of 0.0049 nM.supported
EC50 0.0051 vs 0.0049 nM acsmedchemlett.9b00404
Among all synthetic opioids for which dissociation kinetics have been measured, only protonitazene — a novel nitazene-class compound — demonstrates slower receptor dissociation than carfentanil.supported
Protonitazene dissociates slower than carfentanil; its displacement requires fourfold higher antagonist concentrations. 2026.04.14.718203
Naltrexone is the exception: it demonstrates approximately 65-fold greater potency than naloxone at inhibiting carfentanil-mediated signaling, suggesting that naltrexone accesses or stabilizes receptor states that naloxone cannot effectively engage.supported
Naltrexone ~65x higher potency to inhibit CAR vs naloxone. s00204-025-04048-6
history3 · 1 ok
CDC surveillance documented carfentanil's presence in fentanyl-analog overdose deaths across 10 US states during July–December 2016supported
Fentanyl analogs present in >10% of opioid overdose deaths in four states; carfentanil identified most frequently. mmwr.mm6643e1
Claim in history — inconclusiveinconclusiveworking →
Claim in history — inconclusiveinconclusiveworking →
chemistry1 · 1 ok
The compound is suitable for aerosolization, as demonstrated in its confirmed use as an incapacitating agent in 2002partially supported
Evidence strongly suggests a combination of aerosolized fentanyl derivative (likely carfentanil) and inhalational anesthetic (halothane) was used in the 2002 Moscow theater crisis. pmid:12712038