Cyclobenzaprine Hydrochloride

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Cat Number

API6202239

CAS Number

6202-23-9

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Product Detail Description Scientific Support Customer Q&A

CAS Number

6202-23-9

EINECS

228-264-4

Storage

Room temperature

Synonyms

Cyclobenzaprine HCL; 5-(3-dimethylaminopropylidene)-5h-dibenzo-(a,d)cycloheptenehydrochloride

Molecular Formula

C20H22ClN

Molecular Weight

311.8

Smiles

CN(C)CCC=C1C2=CC=CC=C2C=CC3=CC=CC=C31.Cl

Appearance

White to off-white solid

Melting Point

216-218℃

General Description

Cyclobenzaprine Hydrochloride is a tricyclic compound structurally related to amitriptyline but classified as a centrally acting skeletal muscle relaxant. Its pharmacology centers on brainstem motor pathways.

Mechanism of Action

Cyclobenzaprine acts at the locus coeruleus level within the brainstem, reducing tonic descending facilitation of gamma motor neurons through serotonergic and noradrenergic modulation of spinal reflexes.

Application

Used in the management of acute musculoskeletal spasm. Cyclobenzaprine Hydrochloride is indicated for acute muscle spasms from musculoskeletal conditions, fibromyalgia, and localized muscle injury.

Cyclobenzaprine hydrochloride is a centrally acting skeletal muscle relaxant structurally related to tricyclic antidepressants and first-generation antihistamines. Radioligand binding assays using [³H]-mepyramine demonstrated that cyclobenzaprine exhibits high affinity for the cloned human histamine H1 receptor and for H1 receptors expressed in rat and mouse brain, with low nanomolar affinity. Saturation binding analysis revealed that cyclobenzaprine binds to the H1 receptor in a noncompetitive manner, distinct from the competitive binding of classical H1 antagonists such as diphenhydramine. Functional assays measuring calcium influx and G-protein subunit activation via BRET biosensors confirmed that cyclobenzaprine blocks histamine-mediated H1 receptor functional activity through a noncompetitive mechanism. This H1 receptor antagonism occurs at clinically relevant concentrations and likely contributes to the significant sedative effects observed in patients taking cyclobenzaprine, as the drug readily crosses the blood-brain barrier.

Fig. 1 Antagonism of histamine H1 receptors by Cyclobenzaprine. (Singh K.; et al. 2022)

References

Singh K, et al. The skeletal muscle relaxer cyclobenzaprine is a potent non-competitive antagonist of histamine H1 receptors. The Journal of Pharmacology and Experimental Therapeutics, 2022, 380(3): 202-209.

What distinguishes Cyclobenzaprine from peripherally acting muscle relaxants?

Cyclobenzaprine acts centrally at the brainstem level rather than directly on skeletal muscle, providing relaxation through modulation of descending motor pathways.