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Creation Date 2005-06-13 13:24:05
Update Date 2009-06-23 18:06:52
Primary Accession Number DB00924
Secondary Accession Number
  • APRD00213
Name Cyclobenzaprine
Drug Type
  • Approved
  • Small Molecule
Description Cyclobenzaprine is a skeletal muscle relaxant and a central nervous system (CNS) depressant. Cyclobenzaprine acts on the locus coeruleus where it results in increased norepinephrine release, potentially through the gamma fibers which innervate and inhibit the alpha motor neurons in the ventral horn of the spinal cord. It is structurally similar to Amitriptyline, differing by only one double bond.
Synonyms
  1. Cyclobenzaprine HCL
Brand Names
  1. Cyclobenz
  2. Flexeril
  3. Flexiban
  4. Proeptatriene
  5. Proheptatriene
Brand Mixtures Not Available
Chemical IUPAC Name 3-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-N,N-dimethyl-1-propanamine
Chemical Formula C20H21N
Chemical Structure Structure
CAS Registry Number 303-53-7
InChI Identifier InChI=1/C20H21N/c1-21(2)15-7-12-20-18-10-5-3-8-16(18)13-14-17-9-4-6-11-19(17)20/h3-6,8-14H,7,15H2,1-2H3
InChI Key JURKNVYFZMSNLP-UHFFFAOYAG
KEGG Drug Not Available
KEGG Compound C06931 Link Image
PubChem Compound 2895 Link Image
PubChem Substance 9148 Link Image
ChEBI ID Not Available
PharmGKB ID PA449160 Link Image
HET ID Not Available
GenBank ID Not Available
Drug ID Number [DIN] 02249359 Link Image
RxList Link http://www.rxlist.com/cgi/generic/cyclobnz.htm Link Image
PDRhealth Link http://www.pdrhealth.com/drug_info/rxdrugprofiles/drugs/fle1179.shtml Link Image
Wikipedia Link http://en.wikipedia.org/wiki/Cyclobenzaprine Link Image
FDA Label
Material Safety Data Sheet (MSDS)
Synthesis Reference Villani et al.; J. Org. Med. Pharm. Chem. 5, 373 (1962)
Average Molecular Weight 275.3874
Monoisotopic Molecular Weight 275.1674
State Solid
Melting Point 216-218 oC (HCl salt)
Experimental Water Solubility Freely Soluble Source: PhysProp
Predicted Water Solubility 6.89e-03 mg/mL Calculated using ALOGPS
Experimental LogP/Hydrophobicity 5.2 Source: PhysProp
Predicted LogP 4.73 Calculated using ALOGPS
Experimental LogS Not Available
Predicted LogS -4.60 Calculated using ALOGPS
Experimental Caco2 Permeability Not Available
pKa/Isoelectric Point 8.47
Mass Spectrum Not Available
MOL File Show Link Image | Download Link Image
SDF File Show Link Image | Download Link Image
PDB File Show Link Image | Download Link Image
2D Structure
3D Structure
Experimental PDB ID Not Available
Isomeric SMILES CN(C)CC\C=C1/C2=CC=CC=C2C=CC2=CC=CC=C12
Canonical SMILES CN(C)CCC=C1C2=CC=CC=C2C=CC2=CC=CC=C12
Drug Category
  • Antidepressive Agents, Tricyclic
  • Muscle Relaxants
  • Muscle Relaxants, Central
  • Skeletal Muscle Relaxants
  • Tranquilizing Agents
ATC Codes
AHFS Codes
  • 12:20.00
Indication For use as an adjunct to rest and physical therapy for relief of muscle spasm associated with acute, painful musculoskeletal conditions.
Pharmacology Cyclobenzaprine, closely related to the antidepressant amitriptyline, is used as a skeletal muscle relaxant to reduce pain and tenderness and improve mobility. Unlike dantrolene, cyclobenzaprine cannot be used to treat muscle spasm secondary to cerebral or spinal cord disease.
Mechanism of Action Like other tricyclic antidepressants, cyclobenzaprine exhibits anticholinergic activity, potentiation of norepinephrine, and antagonism of reserpine. Cyclobenzaprine does not directly act on the neuromuscular junction or the muscle but relieves muscle spasms through a central action, possibly at the brain stem level. Cyclobenzaprine binds to the serotonin receptor and is considered a 5-HT2 receptor antagonist that reduces muscle tone by decreasing the activity of descending serotonergic neurons.
Absorption Slowly but well absorbed after oral administration
Toxicity Oral mouse and rat LD50 are 338 mg/kg and 425 mg/kg respectively. Signs of overdose include agitation, coma, confusion, congestive heart failure, convulsions, dilated pupils, disturbed concentration, drowsiness, hallucinations, high or low temperature, increased heartbeats, irregular heart rhythms, muscle stiffness, overactive reflexes, severe low blood pressure, stupor, and vomiting.
Protein Binding Very high (93%)
Biotransformation Extensively metabolized (gastrointestinal and hepatic).
Half Life 18 hours (range 8-37 hours)
Dosage Forms
Form Route
Tablet Oral
Patient Information Show Link Image
Contraindications Show Link Image
Interactions Show Link Image
Drug Interactions
Drug Interaction
Donepezil Possible antagonism of action
Galantamine Possible antagonism of action
Rasagiline Increased risk of toxicity with this association
Rivastigmine Possible antagonism of action
Food Interactions
  • Avoid alcohol.
  • Take with food to reduce irritation.
Pathways Not Available
General References
  1. Drugs.com Link Image
  2. Wikipedia Link Image
  3. RxList Link Image
  4. PDRhealth Link Image
Organisms Affected
  • Humans and other mammals
Phase 1 Metabolizing Enzymes
  1. Cytochrome P450 1A2 (CYP1A2)
Targets
  1. 5-hydroxytryptamine 2A receptor
Phase 1 Metabolizing Enzyme 1 [top]
Enzyme 1 Name Cytochrome P450 1A2 (CYP1A2)
Enzyme 1 Gene Name CYP1A2
Enzyme 1 SwissProt ID P05177 Link Image
Enzyme 1 SNPs SNPJam Report Link Image
Enzyme 1 Protein Sequence >P05177|CP1A2_HUMAN Cytochrome P450 1A2 - Homo sapiens (Human). 
MALSQSVPFSATELLLASAIFCLVFWVLKGLRPRVPKGLKSPPEPWGWPLLGHVLTLGKN
PHLALSRMSQRYGDVLQIRIGSTPVLVLSRLDTIRQALVRQGDDFKGRPDLYTSTLITDG
QSLTFSTDSGPVWAARRRLAQNALNTFSIASDPASSSSCYLEEHVSKEAKALISRLQELM
AGPGHFDPYNQVVVSVANVIGAMCFGQHFPESSDEMLSLVKNTHEFVETASSGNPLDFFP
ILRYLPNPALQRFKAFNQRFLWFLQKTVQEHYQDFDKNSVRDITGALFKHSKKGPRASGN
LIPQEKIVNLVNDIFGAGFDTVTTAISWSLMYLVTKPEIQRKIQKELDTVIGRERRPRLS
DRPQLPYLEAFILETFRHSSFLPFTIPHSTTRDTTLNGFYIPKKCCVFVNQWQVNHDPEL
WEDPSEFRPERFLTADGTAINKPLSEKMMLFGMGKRRCIGEVLAKWEIFLFLAILLQQLE
FSVPPGVKVDLTPIYGLTMKHARCEHVQARRFSIN
Drug Target 1 [top]
Target 1 ID 502
Target 1 Name 5-hydroxytryptamine 2A receptor
Target 1 Synonyms
  1. 5- HT-2
  2. 5-HT-2A
  3. Serotonin receptor 2A
Target 1 Gene Name HTR2A
Target 1 Protein Sequence >5-hydroxytryptamine 2A receptor 
MDILCEENTSLSSTTNSLMQLNDDTRLYSNDFNSGEANTSDAFNWTVDSENRTNLSCEGC
LSPSCLSLLHLQEKNWSALLTAVVIILTIAGNILVIMAVSLEKKLQNATNYFLMSLAIAD
MLLGFLVMPVSMLTILYGYRWPLPSKLCAVWIYLDVLFSTASIMHLCAISLDRYVAIQNP
IHHSRFNSRTKAFLKIIAVWTISVGISMPIPVFGLQDDSKVFKEGSCLLADDNFVLIGSF
VSFFIPLTIMVITYFLTIKSLQKEATLCVSDLGTRAKLASFSFLPQSSLSSEKLFQRSIH
REPGSYTGRRTMQSISNEQKACKVLGIVFFLFVVMWCPFFITNIMAVICKESCNEDVIGA
LLNVFVWIGYLSSAVNPLVYTLFNKTYRSAFSRYIQCQYKENKKPLQLILVNTIPALAYK
SSQLQMGQKKNSKQDAKTTDNDCSMVALGKQHSEEASKDNSDGVNEKVSCV
Target 1 Number of Residues 478
Target 1 Molecular Weight 52604
Target 1 Theoretical pI 7.72
Target 1 GO Classification
Function
signal transducer activity
receptor activity
transmembrane receptor activity
G-protein coupled receptor activity
rhodopsin-like receptor activity
Process
cellular process
cell communication
signal transduction
cell surface receptor linked signal transduction
G-protein coupled receptor protein signaling pathway
Component
cell
membrane
intrinsic to membrane
integral to membrane
Target 1 General Function Involved in rhodopsin-like receptor activity
Target 1 Specific Function This is one of the several different receptors for 5- hydroxytryptamine (serotonin), a biogenic hormone that functions as a neurotransmitter, a hormone, and a mitogen. This receptor mediates its action by association with G proteins that activate a phosphatidylinositol-calcium second messenger system. This receptor is involved in tracheal smooth muscle contraction, bronchoconstriction, and control of aldosterone production
Target 1 Pathways Not Available
Target 1 Reactions Not Available
Target 1 Pfam Domain Function
Target 1 Signals
  • None
Target 1 Transmembrane Regions
  • 76-99
  • 111-132
  • 148-171
  • 192-215
  • 234-254
  • 325-346
  • 363-384
Target 1 Essentiality Non-Essential
Target 1 GenBank ID Protein 36431 Link Image
Target 1 UniProtKB/Swiss-Prot ID P28223 Link Image
Target 1 UniProtKB/Swiss-Prot Entry Name 5HT2A_HUMAN Link Image
Target 1 PDB ID Not Available
Target 1 Cellular Location
  • Cell membrane
  • multi-pass membrane protein. Localizes to the post-synaptic thickening of axo-dendrit
Target 1 Gene Sequence >1416 bp 
ATGGATATTCTTTGTGAAGAAAATACTTCTTTGAGCTCAACTACGAACTCCCTAATGCAA
TTAAATGATGACACCAGGCTCTACAGTAATGACTTTAACTCTGGAGAAGCTAACACTTCT
GATGCATTTAACTGGACAGTCGACTCTGAAAATCGAACCAACCTTTCCTGTGAAGGGTGC
CTCTCACCGTCGTGTCTCTCCTTACTTCATCTCCAGGAAAAAAACTGGTCTGCTTTACTG
ACAGCCGTAGTGATTATTCTAACTATTGCTGGAAACATACTCGTCATCATGGCAGTGTCC
CTAGAGAAAAAGCTGCAGAATGCCACCAACTATTTCCTGATGTCACTTGCCATAGCTGAT
ATGCTGCTGGGTTTCCTTGTCATGCCCGTGTCCATGTTAACCATCCTGTATGGGTACCGG
TGGCCTCTGCCGAGCAAGCTTTGTGCAGTCTGGATTTACCTGGACGTGCTCTTCTCCACG
GCCTCCATCATGCACCTCTGCGCCATCTCGCTGGACCGCTACGTCGCCATCCAGAATCCC
ATCCACCACAGCCGCTTCAACTCCAGAACTAAGGCATTTCTGAAAATCATTGCTGTTTGG
ACCATATCAGTAGGTATATCCATGCCAATACCAGTCTTTGGGCTACAGGACGATTCGAAG
GTCTTTAAGGAGGGGAGTTGCTTACTCGCCGATGATAACTTTGTCCTGATCGGCTCTTTT
GTGTCATTTTTCATTCCCTTAACCATCATGGTGATCACCTACTTTCTAACTATCAAGTCA
CTCCAGAAAGAAGCTACTTTGTGTGTAAGTGATCTTGGCACACGGGCCAAATTAGCTTCT
TTCAGCTTCCTCCCTCAGAGTTCTTTGTCTTCAGAAAAGCTCTTCCAGCGGTCGATCCAT
AGGGAGCCAGGGTCCTACACAGGCAGGAGGACTATGCAGTCCATCAGCAATGAGCAAAAG
GCATGCAAGGTGCTGGGCATCGTCTTCTTCCTGTTTGTGGTGATGTGGTGCCCTTTCTTC
ATCACAAACATCATGGCCGTCATCTGCAAAGAGTCCTGCAATGAGGATGTCATTGGGGCC
CTGCTCAATGTGTTTGTTTGGATCGGTTATCTCTCTTCAGCAGTCAACCCACTAGTCTAC
ACACTGTTCAACAAGACCTATAGGTCAGCCTTTTCACGGTATATTCAGTGTCAGTACAAG
GAAAACAAAAAACCATTGCAGTTAATTTTAGTGAACACAATACCGGCTTTGGCCTACAAG
TCTAGCCAACTTCAAATGGGACAAAAAAAGAATTCAAAGCAAGATGCCAAGACAACAGAT
AATGACTGCTCAATGGTTGCTCTAGGAAAGCAGCATTCTGAAGAGGCTTCTAAAGACAAT
AGCGACGGAGTGAATGAAAAGGTGAGCTGTGTGTGA
Target 1 GenBank Gene ID
Target 1 GeneCard ID HTR2A Link Image
Target 1 GenAtlas ID HTR2A Link Image
Target 1 HGNC ID HGNC:5293 Link Image
Target 1 Chromosome Location 13
Target 1 Locus 13q14-q21
Target 1 SNPs SNPJam Report Link Image
Target 1 General References
  1. Cargill M, Altshuler D, Ireland J, Sklar P, Ardlie K, Patil N, Shaw N, Lane CR, Lim EP, Kalyanaraman N, Nemesh J, Ziaugra L, Friedland L, Rolfe A, Warrington J, Lipshutz R, Daley GQ, Lander ES: Characterization of single-nucleotide polymorphisms in coding regions of human genes. Nat Genet. 1999 Jul;22(3):231-8. [PubMed Link Image]
  2. Marshall SE, Bird TG, Hart K, Welsh KI: Unified approach to the analysis of genetic variation in serotonergic pathways. Am J Med Genet. 1999 Dec 15;88(6):621-7. [PubMed Link Image]
  3. Becamel C, Figge A, Poliak S, Dumuis A, Peles E, Bockaert J, Lubbert H, Ullmer C: Interaction of serotonin 5-hydroxytryptamine type 2C receptors with PDZ10 of the multi-PDZ domain protein MUPP1. J Biol Chem. 2001 Apr 20;276(16):12974-82. Epub 2001 Jan 9. [PubMed Link Image]
  4. Chen K, Yang W, Grimsby J, Shih JC: The human 5-HT2 receptor is encoded by a multiple intron-exon gene. Brain Res Mol Brain Res. 1992 Jun;14(1-2):20-6. [PubMed Link Image]
  5. Stam NJ, Van Huizen F, Van Alebeek C, Brands J, Dijkema R, Tonnaer JA, Olijve W: Genomic organization, coding sequence and functional expression of human 5-HT2 and 5-HT1A receptor genes. Eur J Pharmacol. 1992 Oct 1;227(2):153-62. [PubMed Link Image]
  6. Saltzman AG, Morse B, Whitman MM, Ivanshchenko Y, Jaye M, Felder S: Cloning of the human serotonin 5-HT2 and 5-HT1C receptor subtypes. Biochem Biophys Res Commun. 1991 Dec 31;181(3):1469-78. [PubMed Link Image]
  7. Cook EH Jr, Fletcher KE, Wainwright M, Marks N, Yan SY, Leventhal BL: Primary structure of the human platelet serotonin 5-HT2A receptor: identify with frontal cortex serotonin 5-HT2A receptor. J Neurochem. 1994 Aug;63(2):465-9. [PubMed Link Image]
  8. Erdmann J, Shimron-Abarbanell D, Rietschel M, Albus M, Maier W, Korner J, Bondy B, Chen K, Shih JC, Knapp M, Propping P, Nothen MM: Systematic screening for mutations in the human serotonin-2A (5-HT2A) receptor gene: identification of two naturally occurring receptor variants and association analysis in schizophrenia. Hum Genet. 1996 May;97(5):614-9. [PubMed Link Image]
Target 1 Drug References
  1. Honda M, Nishida T, Ono H: Tricyclic analogs cyclobenzaprine, amitriptyline and cyproheptadine inhibit the spinal reflex transmission through 5-HT(2) receptors. Eur J Pharmacol. 2003 Jan 1;458(1-2):91-9. [PubMed Link Image]
  2. Kobayashi H, Hasegawa Y, Ono H: Cyclobenzaprine, a centrally acting muscle relaxant, acts on descending serotonergic systems. Eur J Pharmacol. 1996 Sep 5;311(1):29-35. [PubMed Link Image]

This project is supported by Genome Alberta & Genome Canada, a not-for-profit organization that is leading Canada's national genomics strategy with $600 million in funding from the federal government. This project is also supported in part by GenomeQuest, Inc., an enterprise genomic information company serving the life science community.