Cyclobenzaprine
Also called Fexmid.
A muscle relaxant sold as Flexeril, used short term for muscle spasm. Its skeleton is a tricyclic antidepressant's, one double bond apart from amitriptyline.
Sources and notes
- The introductionfrom sourceMoleculeFinder curated
- Other namesfrom sourceWikidataIts English label and aliases on Wikidata.
- Formula and weightcomputedPubChem
- 2D drawingcomputedPubChem structure, drawn by RDKit
- 3D modelfrom sourcePubChem 3D conformerLoaded after the page has painted, and on a phone only when you ask for it; the 2D drawing shows until it arrives.
Where you encounter it
Dispensed on prescription, not sold on a shelf. Cyclobenzaprine on the product labels we hold.
Medicines
Every product and list we hold
Sources and notes
- The product labels and their strengthsfrom sourceDailyMed (FDA label)Each label lists the molecule as an ingredient, and an active ingredient at the strength shown.
- How it gets therefrom sourceMoleculeFinder curatedEach mark is set by hand on our lists, never inferred; a label's ingredient is added by the maker. A row with no mark data says Not marked.
- The line abovefrom sourceMoleculeFinder curatedFrom the group the molecule belongs to.
Explore its structure
Choose a part to light it up.
A nitrogen bonded to three carbons, with no hydrogen of its own. Its spare pair of electrons can still pick up a hydrogen ion, so a tertiary amine is a base.
From: standard chemistry.
Rings joined where they share atoms, or a single ring standing alone. Atoms in a ring are held in place, so this part keeps its shape while chains around it can bend.
From: standard chemistry.
Sources and notes
- The drawingcomputedPubChem structure, drawn by RDKitThe page's one shipped drawing, with the chosen part lit in amber under it.
- The partscomputedFound by ruleEach part is found by a chemical pattern, never picked by hand atom by atom; its words say where they come from.
Properties and sources
Calculated by PubChem
- Molecular formula
- C20H21N
- Molecular weight
- 275.4 g/mol
- XLogP3octanol/water, log units
- 5.2
- Polar surface areatopological
- 3.2 Ų
- H-bond donors
- 0
- H-bond acceptors
- 1
- Rotatable bonds
- 3
- Complexity
- 365
Measured LD50, HSDB via PubChem
425 mg/kg pure cyclobenzaprine, rat, oral
An LD50 is an animal study measurement, not a dose for a person.
Reported Hazard label (GHS), HSDB via PubChem
Danger Toxic pictogram (GHS06) and Irritant pictogram (GHS07); hazard statements H301, H312, H332
Reported Licence
The US Food and Drug Administration licenses Cyclobenzaprine for human use (NDA 021777, authorized February 1, 2007). Drugs@FDA
Groups it belongs to
- Category
- Prescription medicine
- Family
- Muscle relaxants
- Chemical groups
- Aromatics
- Elements
- Nitrogen
- Hazard classes
- Acutely toxic, Irritant, GHS Danger
CN(C)CCC=C1C2=CC=CC=C2C=CC3=CC=CC=C31PubChem CID 2895 · Wikidata Q5198674 · InChIKey JURKNVYFZMSNLP-UHFFFAOYSA-N · Data refreshed
Questions
- What is Cyclobenzaprine?
- A muscle relaxant sold as Flexeril, used short term for muscle spasm. Its skeleton is a tricyclic antidepressant's, one double bond apart from amitriptyline.
- How toxic is Cyclobenzaprine?
- The reported LD50 of Cyclobenzaprine is 425 mg/kg (rat, oral). An LD50 is an animal study measurement, not a dose for a person. Its GHS hazard label carries the signal word Danger and the hazard pictograms Toxic and Irritant. from sourcefrom source
- What kind of molecule is Cyclobenzaprine?
- Cyclobenzaprine has the formula C20H21N and a molecular weight of 275.4 g/mol. MoleculeFinder files it under muscle relaxants, in the prescription medicine group. from sourcefrom sourcefrom sourcefrom source
- What else is Cyclobenzaprine called?
- Cyclobenzaprine is also called Fexmid. from source
- Who licenses Cyclobenzaprine as a medicine?
- The US Food and Drug Administration licenses Cyclobenzaprine for human use (NDA 021777, authorized February 1, 2007). from source
Sources and notes
- Calculated valuescomputedPubChemComputed from the structure, so no laboratory conditions apply; complexity is PubChem's own structural score.
- LD50from sourceHSDB via PubChemOther values the sources report: mouse, oral, 250 mg/kg; mouse, oral, 338 mg/kg; mouse, intravenous, 36 mg/kg; mouse, another route, 90 mg/kg. The page shows the one LD50 the site uses everywhere.
- Hazard labelfrom sourceHSDB via PubChemThe label combines these classifications.
- Licencefrom sourceDrugs@FDARead 2026-10-21.
- Data refreshedfrom sourceMoleculeFinder2026-11-09
Keep exploring
Sources and notes
- Similar in shapecomputedRDKit Morgan/TanimotoNeighbours by structural fingerprint; the sentence names the chemical groups the two share.
- The drawingscomputedPubChem structures, drawn by RDKit