generation run 2026-04-27
62 min completedmodel pipeline-v5plan not recordedrun/0e4c5330…Selection
Verification
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The model's own caveats
- taper_protocol_class_level
- samhsa_tip63_edition
Reproduce
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- 40 source keys (listed under Sources)
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17 searches — query, source, results, what was kept and why
| # | source | query | seen | kept | rationale |
|---|---|---|---|---|---|
| 1 | PubChem | morphine | 1 | 1 | Primary chemical identity data; confirms brief's partial data and fills missing fields |
| 2 | PubMed | morphine overdose lethal dose opioid toxicity naloxone reversal | 4 | 1 | Hill 2020 directly compares fentanyl, heroin and morphine respiratory depression in controlled conditions |
| 3 | PubMed | morphine history discovery Sertürner 1804 opium alkaloid | 1 | 3 | All three highly relevant to morphine history and chemistry |
| 4 | PubMed | morphine morphine-6-glucuronide M6G M3G UGT2B7 metabolism active metabolite | 5 | 2 | — |
| 5 | PubMed | morphine pharmacokinetics bioavailability half-life metabolism human | 10 | 2 | — |
| 6 | PubMed | morphine receptor binding affinity mu opioid kappa Ki EC50 | 10 | 1 | — |
| 7 | PubMed | morphine human pharmacokinetics oral bioavailability half-life glucuronidation | 10 | 1 | — |
| 8 | OpenAlex | crystal structure mu-opioid receptor morphine inactive active state (citations) | 6 | 3 | Landmark receptor structure and opioid pharmacology reviews directly relevant to morphine mechanism |
| 9 | Crossref/DOI | 10.1038/nature10954 | 1 | 1 | Foundational inactive-state crystal structure paper for µ-opioid receptor, directly relevant to morphine binding site understanding |
| 10 | WebSearch/DEA/Government | morphine DEA Schedule II UK Class A Australia Schedule 8 Canada CDSA Schedule I | 10 | 1 | Essential legal status data for all major jurisdictions |
| 11 | OpenAlex | morphine opioid receptor pharmacology analgesia (citations) | 8 | 1 | — |
| 12 | PubMed | morphine tolerance dependence physical withdrawal opioid use disorder | 5 | 1 | — |
| 13 | IUPHAR/BPS Guide to Pharmacology | mu opioid receptor morphine binding affinity Ki | 1 | 1 | Authoritative primary pharmacology database; most reliable Ki data available |
| 14 | PubMed PMID fetch | Multiple PMID fetches for key papers | 8 | 1 | Core pharmacology, history, and mechanism papers for the article |
| 15 | WebSearch | morphine CAS number 57-27-2 melting point water solubility physical properties base sulfate | 10 | 3 | Physical properties essential for chemical identity section |
| 16 | WebSearch | morphine DEA Schedule II UK Class A Australia Schedule 8 Canada CDSA | 10 | 1 | Legal status confirmed for article legal section |
| 17 | WebSearch | morphine Ki mu opioid receptor nM radioligand binding PDSP NIMH database | 10 | 2 | Key binding affinity papers for morphine MOR pharmacology |
86 claims by section — every cited sentence, checked against its source
pharmacology21 · 18 ok
Claim in pharmacology — inconclusiveinconclusiveworking →
MOR activation produces three key downstream signaling events:supported
Describes functional organization, pharmacology, signaling mechanisms, and loci of opioid analgesic action along peripheral and central pain pathways. annurev-neuro-080317-061522
MOR activation produces three key downstream signaling events:supported
Reviews mu receptor structure/function, biased agonists, bivalent ligands, allosteric modulators, receptor phosphorylation, and alternative pre-mRNA splicing producing multiple mu receptor isoforms. 164_2019_270
Quinidine-mediated P-gp inhibition significantly increases morphine oral bioavailability and brain penetration in humans.supported
Tests hypothesis that plasma concentrations and clinical effects of oral and intravenous morphine are greater after inhibition of intestinal and brain P-glycoprotein with quinidine; morphine is a P-glycoprotein substrate. pmid:14663457
Oral bioavailability of immediate-release morphine is 20–40%, limited by extensive first-pass glucuronidation in the liver and gut wallsupported
Oral bioavailability approximately 40% with marked patient-to-patient variations. pmid:3514045
Oral bioavailability of immediate-release morphine is 20–40%, limited by extensive first-pass glucuronidation in the liver and gut wallsupported
Oral-parenteral potency ratio 1:3 due to first-pass metabolism. Glucuronidation primary metabolism. pmid:2057987
The oral-to-parenteral potency ratio is approximately 1:3supported
Oral-parenteral potency ratio 1:3 due to first-pass metabolism. pmid:2057987
Time to peak plasma concentration (Tmax) is 30–90 minutes for oral immediate-release formulations and 15–20 minutes for intramuscular or subcutaneous injection.supported
Peak plasma 15-20 min IM/SC; 30-90 min oral. pmid:2057987
Volume of distribution is 1–6 L/kg with large interindividual variabilitypartially supported
Volume of distribution 1.0–4.7 L/kg. pmid:3514045
Morphine is primarily metabolized by hepatic UDP-glucuronosyltransferase 2B7 (UGT2B7), yielding two major glucuronide conjugates:supported
UGT2B7 expressed in human liver, lung, kidney; catalyzes M3G and M6G formation from morphine. aps.2016.157
Morphine is primarily metabolized by hepatic UDP-glucuronosyltransferase 2B7 (UGT2B7), yielding two major glucuronide conjugates:supported
Morphine is primarily metabolized by UGT2B7 to M3G (inactive) and M6G (active). pharmaceutics16030418
Morphine-3-glucuronide (M3G): Comprises ~75–80% of glucuronide output. Inactive at MOR; paradoxically may antagonize morphine analgesia and contribute to neuroexcitatory effects (hyperalgesia, myoclonus) at high concentrations. M3G:morphine plasma ratio is approximately 10:1 after intravenous dosing and 20:1 after oral dosing.supported
M3G levels exceed parent drug ~10-fold IV, ~20-fold oral. pmid:3514045
Morphine-3-glucuronide (M3G): Comprises ~75–80% of glucuronide output. Inactive at MOR; paradoxically may antagonize morphine analgesia and contribute to neuroexcitatory effects (hyperalgesia, myoclonus) at high concentrations. M3G:morphine plasma ratio is approximately 10:1 after intravenous dosing and 20:1 after oral dosing.partially supported
M3G (inactive) principal metabolite; M6G active and more potent. M6G:morphine ~10:1 in plasma. pmid:2057987
Morphine-6-glucuronide (M6G): Comprises ~15–20% of glucuronide output. Active MOR full agonist, significantly more potent than morphine per unit mass. Accumulates in renal insufficiency, producing prolonged and enhanced opioid effects.supported
M6G active and more potent. M6G:morphine ~10:1 in plasma. Renal insufficiency causes metabolite accumulation. pmid:2057987
Morphine-6-glucuronide (M6G): Comprises ~15–20% of glucuronide output. Active MOR full agonist, significantly more potent than morphine per unit mass. Accumulates in renal insufficiency, producing prolonged and enhanced opioid effects.supported
Some patients with renal dysfunction suffer side effects from morphine due to M6G accumulation. A118G SNP of OPRM1 may result in decreased potency of M6G. pmid:12357145
Claim in pharmacology — inconclusiveinconclusiveworking →
UGT2B7 genetic polymorphisms (e.g., UGT2B7*2) alter the M3G:M6G ratio, contributing to interindividual variability in analgesic responsesupported
Allelic variants of UGT2B7, UGT1A1 and UGT1A9 regioselectively affect M3G:M6G ratio. aps.2016.157
The OPRM1 A118G single-nucleotide polymorphism may reduce M6G potency at MOR.supported
A118G SNP of OPRM1 may result in decreased potency of M6G. pmid:12357145
Elimination half-life is approximately 2–4 hours, though published values range from 0.7 to 7.8 hours reflecting large interindividual variabilitysupported
Elimination half-life 0.7–7.8 hours. pmid:3514045
Renal insufficiency causes M6G accumulation, producing enhanced and prolonged opioid effects and elevated toxicity risksupported
M6G active and more potent. Renal insufficiency causes metabolite accumulation. pmid:2057987
Claim in pharmacology — inconclusiveinconclusiveworking →
safety21 · 17 ok
Tolerance loss after periods of abstinence (incarceration, hospitalization, treatment completion) is a primary risk factor for fatal overdose — return to pre-abstinence doses can be lethal.supported
Losses of tolerance and concomitant CNS depressant use clearly play major role. pmid:11487418
Tolerance loss after periods of abstinence (incarceration, hospitalization, treatment completion) is a primary risk factor for fatal overdose — return to pre-abstinence doses can be lethal.supported
Loss of tolerance after abstinence is key overdose risk factor. journal.pone.0269379
Morphine ED₅₀ for antinociception in rats (hot plate test, subcutaneous) is approximately 3.94 mg/kg.supported
Morphine ED50 in rat hot plate test = 3.940 mg/kg s.c. s00204-022-03276-4
The primary mechanism of acute morphine toxicity is dose-dependent respiratory depression through MOR agonism in the brainstem pre-Bötzinger complex, leading to progressive hypercapnia, hypoxia, coma, and deathsupported
Characterized how fentanyl depresses respiration and compared with heroin and morphine (active breakdown product of heroin). Examined factors beyond potency contributing to lethality. bph.14860
The primary mechanism of acute morphine toxicity is dose-dependent respiratory depression through MOR agonism in the brainstem pre-Bötzinger complex, leading to progressive hypercapnia, hypoxia, coma, and deathsupported
Most opioid-related deaths caused by respiratory depression. Conventional opioids (morphine, oxycodone, fentanyl) purely driven by µ-opioid receptor agonism. jom.2021.0648
Claim in safety — inconclusiveinconclusiveworking →
This produces prolonged and enhanced opioid effects — including life-threatening respiratory depression — even after morphine itself has been cleared from plasmasupported
M6G active and more potent. M6G:morphine ~10:1 in plasma. Renal insufficiency causes metabolite accumulation. pmid:2057987
This produces prolonged and enhanced opioid effects — including life-threatening respiratory depression — even after morphine itself has been cleared from plasmasupported
Some patients with renal dysfunction suffer side effects from morphine due to M6G accumulation. pmid:12357145
The OPRM1 A118G polymorphism may modify M6G potency, conferring differential risk across individuals.supported
A118G SNP of OPRM1 may result in decreased potency of M6G. pmid:12357145
Mechanisms involve spinal astrocyte JNK/NMDA/PKC pathway activation, descending facilitation from the RVM, and spinal dynorphin upregulationpartially supported
PKC-NMDA-JNK pathway involved. Neuronal MOR triggers astrocyte JNK pathway, contributing to ultra-low-dose morphine hyperalgesia. j.pain.0000000000000164
OIH manifests as diffuse pain unrelated to the original pain site and characteristically worsens with dose escalation — distinguishing it from tolerance-related loss of efficacy.supported
OIH appears to be a distinct, definable phenomenon that could explain loss of opioid efficacy in some patients. 00000542-200603000-00025
Morphine produces dose-dependent cognitive euphoria, anxiolysis, and a compulsive redosing urge — effects mediated by MOR activation in the nucleus accumbens and amygdalapartially supported
Morphine alone increased euphoria (MBG scale) and liking scores. pmid:3720527
Claim in safety — inconclusiveinconclusiveworking →
Tolerance develops via adenylyl cyclase superactivation (Gβγ-mediated upregulation of AC-V and AC-VIII) and sustained MOR desensitization without adequate receptor recycling due to poor β-arrestin-mediated internalizationpartially supported
Chronic morphine exposure leads to adenylyl cyclase superactivation (increase in cAMP accumulation). Prevented by pertussis toxin (Gi/o involvement) and Gbetagamma scavengers. pmid:8702909
Tolerance develops via adenylyl cyclase superactivation (Gβγ-mediated upregulation of AC-V and AC-VIII) and sustained MOR desensitization without adequate receptor recycling due to poor β-arrestin-mediated internalizationsupported
Remifentanil induced rapid receptor internalization compared to morphine. j.neuropharm.2013.06.010
Alcohol is consistently identified as a co-intoxicant in postmortem opioid toxicology series.supported
Losses of tolerance and concomitant CNS depressant use clearly play major role. pmid:11487418
Claim in safety — inconclusiveinconclusiveworking →
Static modeling predicts clinically significant elevation of morphine and M6G plasma levels with concurrent cannabis use.supported
Modeling predicts clinically relevant DDI between morphine and inhaled cannabis (THC) and oral cannabis (THC, CBD). pharmaceutics16030418
Tramadol's additional serotonergic activity (SNRI mechanism) does not substantially interact with morphine, which has minimal serotonergic propertiessupported
Morphine itself has lower serotonergic activity than tramadol/meperidine. s00482-015-1512-0
Renal insufficiency: M6G accumulation produces enhanced and prolonged opioid effects; dose reduction and monitoring required.supported
M6G active and more potent. Renal insufficiency causes metabolite accumulation. pmid:2057987
Claim in safety — inconclusiveinconclusiveworking →
summary10 · 9 ok
Claim in summary — inconclusiveinconclusiveworking →
Morphine was the first alkaloid isolated from any plant — extracted by Friedrich Sertürner in 1804 — and its characterization launched the fields of alkaloid chemistry and receptor pharmacologypartially supported
Alkaloid chemistry began with the isolation of morphine from crude opium by Friedrich Wilhelm Adam Sertürner in 1804. ijms26062736
Morphine was the first alkaloid isolated from any plant — extracted by Friedrich Sertürner in 1804 — and its characterization launched the fields of alkaloid chemistry and receptor pharmacologysupported
history from first extraction and isolation by Sertürner in 1804 to illicit use and opioid use and abuse disorders. acschemneuro.8b00150
It remains on the WHO Essential Medicines List as the Step III strong opioid reference analgesic and is increasingly studied for chronic breathlessnesssupported
Assessed effectiveness of oral morphine for breathlessness in long-term conditions; multi-site UK RCT. s2213-2600(25)00205-x
Morphine milligram equivalents (MME) remain the standard unit for comparing opioid doses in clinical and regulatory contexts.supported
morphine milligram equivalents (MME) as reference standard for dose comparisons; thresholds at 50 and 90 MME/day. mmwr.rr6501e1
Morphine activates Gi/o-coupled MOR, inhibiting adenylyl cyclase, opening GIRK potassium channels, and closing voltage-gated calcium channels — collectively hyperpolarizing nociceptive neurons and reducing neurotransmitter release in pain-processing pathwayssupported
Describes functional organization, pharmacology, signaling mechanisms, and loci of opioid analgesic action along peripheral and central pain pathways. annurev-neuro-080317-061522
Morphine carries a critical acute toxicity profile: dose-dependent respiratory depression via brainstem pre-Bötzinger complex MOR agonism is the primary cause of overdose death, and the therapeutic index narrows sharply with tolerance loss after abstinencepartially supported
Characterized how fentanyl depresses respiration and compared with heroin and morphine (active breakdown product of heroin). Examined factors beyond potency contributing to lethality. bph.14860
Morphine carries a critical acute toxicity profile: dose-dependent respiratory depression via brainstem pre-Bötzinger complex MOR agonism is the primary cause of overdose death, and the therapeutic index narrows sharply with tolerance loss after abstinencepartially supported
Losses of tolerance and concomitant CNS depressant use clearly play major role. Mechanism remains unclear. pmid:11487418
Physical and psychological dependence liability are high; tolerance develops via adenylyl cyclase superactivation and poor MOR internalization, driving dose escalationsupported
Chronic morphine exposure leads to adenylyl cyclase superactivation (increase in cAMP accumulation), implicated in opiate addiction. Prevented by pertussis toxin (Gi/o involvement) and Gbetagamma scavengers. pmid:8702909
The active metabolite morphine-6-glucuronide accumulates in renal insufficiency, creating an under-recognized toxicity pathwaysupported
M6G active and more potent. M6G:morphine ~10:1 in plasma. Urinary free morphine <10%. Renal insufficiency causes metabolite accumulation. pmid:2057987
history7 · 3 ok
Claim in history — inconclusiveinconclusiveworking →
Opium — the dried latex of Papaver somniferum seed capsules — has been used by humans for at least 8,000 years, with archaeological evidence of cultivation dating to the sixth millennium BCE in Mesopotamiasupported
Evidence of human use of opium dates back as far as the sixth millennium BCE. j.janh.2017.02.001
Claim in history — inconclusiveinconclusiveworking →
His work represented the founding moment of modern alkaloid chemistry and established the principle that plant extracts contain discrete pharmacologically active molecules.supported
Alkaloid chemistry began with the isolation of morphine from crude opium by Friedrich Wilhelm Adam Sertürner in 1804. ijms26062736
The empirical formula was established through successive analytical studies in the 19th century. Sir Robert Robinson derived morphine's correct structural formula in the early 20th century — work for which he received the Nobel Prize in Chemistry in 1947supported
Sir Robert Robinson's derivation of morphine's structural formula won him the 1947 Nobel Prize in Chemistry. j.janh.2017.02.001
Claim in history — inconclusiveinconclusiveworking →
Claim in history — inconclusiveinconclusiveworking →
neuroscience7 · 5 ok
This is the primary mechanism of opioid overdose death.supported
Characterized how fentanyl depresses respiration and compared with heroin and morphine (active breakdown product of heroin). Examined factors beyond potency contributing to lethality. bph.14860
This is the primary mechanism of opioid overdose death.supported
Most opioid-related deaths caused by respiratory depression. jom.2021.0648
Claim in neuroscience — inconclusiveinconclusiveworking →
Claim in neuroscience — inconclusiveinconclusiveworking →
Chronic morphine exposure induces adenylyl cyclase superactivation — specifically upregulation of adenylyl cyclase isoforms V and VIII mediated by Gβγ dimers — producing a compensatory increase in cAMP signaling that opposes ongoing opioid effectssupported
Chronic morphine exposure leads to adenylyl cyclase superactivation (increase in cAMP accumulation). Prevented by pertussis toxin (Gi/o involvement) and Gbetagamma scavengers. pmid:8702909
Spinal astrocyte activation via JNK/NMDA/PKC pathways contributes to morphine-induced hyperalgesia, a paradoxical pain sensitization phenomenon observed even at ultra-low doses.supported
Ultra-low-dose morphine activated spinal astrocytes with no effect on microglia. JNK inhibitor prevented morphine hyperalgesia. PKC-NMDA-JNK pathway involved. j.pain.0000000000000164
Individual variation in M6G response: The OPRM1 A118G polymorphism appears to modulate M6G potency, but clinical studies have produced inconsistent results regarding its impact on analgesic outcomes.supported
A118G SNP of OPRM1 may result in decreased potency of M6G. pmid:12357145
pharmacokinetic-detail6 · 5 ok
UGT2B7 is the principal enzyme responsible for morphine phase II metabolism, catalyzing glucuronidation at two positions: the C-3 phenol (producing M3G) and the C-6 hydroxyl (producing M6G)supported
UGT2B7 expressed in human liver, lung, kidney; catalyzes M3G and M6G formation from morphine. aps.2016.157
UGT2B7 is the principal enzyme responsible for morphine phase II metabolism, catalyzing glucuronidation at two positions: the C-3 phenol (producing M3G) and the C-6 hydroxyl (producing M6G)supported
Morphine is primarily metabolized by UGT2B7 to M3G (inactive) and M6G (active). pharmaceutics16030418
Claim in pharmacokinetic-detail — inconclusiveinconclusiveworking →
Its clinical significance is magnified in renal insufficiency, where impaired clearance produces accumulation and prolonged opioid effects including life-threatening respiratory depressionsupported
Some patients with renal dysfunction suffer side effects from morphine due to M6G accumulation. pmid:12357145
The OPRM1 A118G polymorphism (present in ~15–30% of individuals of European ancestry) may reduce M6G potency at MOR, partially explaining interindividual variability in morphine response.partially supported
A118G SNP of OPRM1 may result in decreased potency of M6G. pmid:12357145
Mechanistic static modeling predicts clinically significant in vivo drug-drug interactions between morphine and both inhaled cannabis (THC) and oral cannabis products (THC, CBD), with elevated morphine and M6G plasma levels as the expected consequence.supported
Modeling predicts clinically relevant DDI between morphine and inhaled cannabis (THC) and oral cannabis (THC, CBD). pharmaceutics16030418
clinical-evidence4 · 3 ok
A Cochrane overview of systematic reviews confirmed morphine's efficacy in cancer pain management, though the evidence base is limited by heterogeneous study designs and small sample sizes typical of palliative care researchsupported
Opioid drugs including morphine recommended in WHO pain treatment ladder. Most commonly used opioids include morphine, oxycodone, fentanyl, hydromorphone, buprenorphine, codeine. 14651858.cd012592.pub2
Claim in clinical-evidence — inconclusiveinconclusiveworking →
A systematic review and meta-analysis of opioids for cancer-related dyspnea confirmed that systemic morphine was more effective than placebo for dyspnea managementsupported
Opioids more effective than placebo for dyspnea (SMD -0.43, 95% CI -0.75 to -0.12). Significant difference between systemic morphine and placebo in drug-specific analysis. s10147-023-02362-6
A double-blind, placebo-controlled RCT compared fentanyl buccal tablet and morphine for exertional dyspnea in patients with cancer, providing direct comparative data on two opioids in the dyspnea indication.supported
Randomised trial comparing daily prophylactic fentanyl buccal tablet, oral morphine, and placebo on exertional dyspnoea over 14 days in cancer patients. thorax-2025-222970
comparative-pharmacology4 · 4 ok
The morphine milligram equivalent (MME) system, formalized by the CDC in 2016, uses oral morphine as the denominator for dose equivalence calculations across the opioid class.supported
morphine milligram equivalents (MME) as reference standard for dose comparisons; thresholds at 50 and 90 MME/day. mmwr.rr6501e1
β-arrestin2 recruitment data from Vandeputte et al. (2022); relative potency values from clinical equianalgesic tables.supported
Morphine EC50 in MOR-β-arrestin2 assay = 290 nM. s00204-022-03276-4
The clinical relevance of biased agonism — specifically whether reduced β-arrestin recruitment translates to a wider therapeutic index — remains an active area of investigation.supported
Reviews mu receptor structure/function, biased agonists, bivalent ligands, allosteric modulators, receptor phosphorylation, and alternative pre-mRNA splicing producing multiple mu receptor isoforms. 164_2019_270
Morphine's pharmacokinetic variability is instead driven by UGT2B7 polymorphisms and P-glycoprotein expression.supported
Allelic variants of UGT2B7, UGT1A1 and UGT1A9 regioselectively affect M3G:M6G ratio. aps.2016.157
receptor-pharmacology4 · 3 ok
Specific morphine Ki values at human KOR and DOR from a single radioligand binding study were not located in this review; the estimates derive from class-level comparative literature.supported
Morphine MOR potency reference in GTPγS assay. j.neuropharm.2017.08.016
In a human MOR β-arrestin2 recruitment functional assay, morphine EC₅₀ = 290 nM — substantially less potent than fentanyl (EC₅₀ = 14.9 nM) at β-arrestin2 recruitmentsupported
Morphine EC50 in MOR-β-arrestin2 assay = 290 nM. s00204-022-03276-4
Claim in receptor-pharmacology — inconclusiveinconclusiveworking →
The morphine binding pose involves a salt bridge between its protonated tertiary amine nitrogen and the conserved Asp147(3.32) residue in the MOR orthosteric binding pocketsupported
Fentanyl and morphine have partially overlapping binding pockets at MOR; fentanyl maintains additional TM2 interaction. Piperidine nitrogen establishes salt-bridge with D-147(3.32). j.bcp.2020.114293