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Research tools

PF-04457845

An irreversible FAAH inhibitor, a research molecule: raises anandamide without touching CB1.

Unscheduled
Level of detail

Harm-reduction warning

No characterised human dose: animal / in vitro data only. Effect profile, safety margin and acute toxicity are not documented in human clinical practice. Extremely potent compound: severe effects, seizures and deaths reported in the literature.

C₂₃H₂₀F₃N₅O₂

CAS 1020315-31-4

Family
ECS pharmacological toolEnzyme inhibitor
Molar mass
455.40 g/mol

Updated on

In plain terms

PF-04457845 is a laboratory molecule with no link to hemp. Instead of imitating cannabis, it blocks the enzyme that destroys anandamide, a substance the body makes itself, so that more of it circulates. It has been tested in knee osteoarthritis, cannabis dependence and post-traumatic stress, but it has never been authorised as a medicine and is in no product on sale.

Receptors and activity

Target network

FAAHInhibitorIC50 = 7.2 nM · humanirreversible covalent inhibition; kinact/Ki of 40,300 M-1 s-1
  • Blocks or inhibits

The lower the cited value, the closer the target sits to PF-04457845: one ring per factor of 100. A target with no measured value stays on the edge.

Where these targets live

Where each target has been found in humans, according to the cited studies. The map shows the target, not an effect of PF-04457845.

Brain, side view
Body, front view
Blood

FAAHFAAH found in 7 regions of the body

  1. CortexpresentCortical pyramidal neurons1
  2. Basal gangliapresentStriatal neurons1
  3. HypothalamuspresentPresent in hypothalamic nuclei1
  4. CerebellumpresentPurkinje cells and cerebellar layers1
  5. BrainstempresentInferior olivary nuclei1
  6. Adipose tissuepresentExpressed in mature adipocytes2
  7. BonepresentPresent on osteoclasts3

Map sources

  1. Romero J et al. Fatty acid amide hydrolase localization in the human central nervous system: an immunohistochemical study. Brain Res Mol Brain Res, 2002 (new tab)
  2. Engeli S et al. Activation of the peripheral endocannabinoid system in human obesity. Diabetes, 2005 (new tab)
  3. Rossi F et al. The endovanilloid/endocannabinoid system in human osteoclasts: possible involvement in bone formation and resorption. Bone, 2009 (new tab)

Cited values

  1. FAAHInhibitorIC50 = 7.2 nM · human69 out of 100

    Johnson et al., ACS Med Chem Lett 2011 (new tab) · irreversible covalent inhibition; kinact/Ki of 40,300 M-1 s-1

Bar length follows the measured value (Ki, Kd, EC50 or IC50), on one scale shared by every entry, from 100 µM to 0.1 nM. A target with no cited value has no bar.

Pharmacology

PF-04457845 is an irreversible and highly selective inhibitor of FAAH, the enzyme that breaks down anandamide. It carbamylates the nucleophilic serine of the enzyme, with an IC50 of 7.2 nM on the human protein (Johnson et al. 2011). It does not bind CB1 or CB2: its action is indirect, through accumulation of anandamide and related ethanolamides. In humans this biochemical effect is firmly established: leukocyte FAAH activity is inhibited by more than 97% at doses of at least 0.3 mg (Li et al. 2012) and brain activity by 91% or more, measured by positron emission tomography (Boileau et al. 2015). Clinical translation is disappointing, however: in knee osteoarthritis, the trial (74 patients) was stopped for futility at the interim analysis, the molecule not differing from placebo whereas the comparator naproxen appeared effective (Huggins et al. 2012). A phase 2a trial in men dependent on cannabis (46 on treatment, 24 on placebo) found fewer withdrawal symptoms and less cannabis use on treatment (D'Souza et al. 2019), an isolated result that needs confirmation. A 2026 review concludes a modest benefit in cannabis use disorder and no efficacy in post-traumatic stress or osteoarthritis pain (Couttas et al. 2026).

Key sources.

History

Source
An entirely synthetic molecule, arising from a pharmaceutical medicinal-chemistry programme. It occurs neither in hemp nor in any other plant, and has never been identified as a natural product. It has never obtained a marketing authorisation and remains a pharmacological research tool and an investigational medicine.

Origin

Research tool

No known biosynthetic pathway: no living organism produces this molecule, a synthetic heteroaromatic urea (a piperidine substituted by an aryl ether, linked to an aminopyridazine).

Classification

Family, origin and source verification

Family

ECS pharmacological tool › Enzyme inhibitor

Verification

Classification, sources and binding values checked on 20 October 2026; text read against its sources and Wikipedia.

Wikipedia (English)

Redafamdastat (new tab)

Article paired by the molecule's structure (InChIKey), revision read on 19 October 2026. Read as a second opinion, never cited as a source.

References

  1. Johnson DS et al., ACS Med Chem Lett 2011: discovery of PF-04457845 (new tab)PMID 21666860
  2. Li GL et al., Br J Clin Pharmacol 2012: pharmacology and tolerability in healthy volunteers (new tab)PMID 22044402
  3. Huggins JP et al., Pain 2012: trial in knee osteoarthritis (new tab)PMID 22727500
  4. D'Souza DC et al., Lancet Psychiatry 2019: cannabis withdrawal and dependence in men (new tab)PMID 30528676
  5. Boileau I et al., J Cereb Blood Flow Metab 2015: blockade of brain FAAH, positron emission tomography (new tab)PMID 26082009
  6. van Esbroeck ACM et al., Science 2017: non-FAAH targets of BIA 10-2474 (new tab)PMID 28596366
  7. Bonifácio MJ et al., Br J Pharmacol 2020: preclinical evaluation of BIA 10-2474 (comparison with PF-04457845) (new tab)PMID 31901141
  8. Couttas TA et al., Transl Psychiatry 2026: FAAH inhibition in psychiatry (new tab)PMID 42209468
  9. ClinicalTrials.gov NCT05178316: trial of JZP150 in post-traumatic stress disorder (Jazz Pharmaceuticals) (new tab)
  10. PubChem, PF-04457845, CID 24771824 (identifiers, formula) (new tab)

Identifiers

Names

IUPAC name
N-pyridazin-3-yl-4-[[3-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenyl]methylidene]piperidine-1-carboxamide
Other names
PF-4457845 · redafamdastat · JZP-150

Identifiers

Formula
C₂₃H₂₀F₃N₅O₂
CAS
1020315-31-4
PubChem CID
24771824(new tab)
InChIKey
BATCTBJIJJEPHM-UHFFFAOYSA-N
SMILES
C1CN(CCC1=CC2=CC(=CC=C2)OC3=NC=C(C=C3)C(F)(F)F)C(=O)NC4=NN=CC=C4

Machine-readable entry (JSON)

LLM ingestion format: a structured superset of the entry (identifiers, binding, versioned legal status). Full corpus.