Cyclobenzaprine Hydrochloride
(sye'' kloe ben' za preen hye'' droe klor' ide).
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C20H21N·HCl 311.85

1-Propanamine, 3-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-N,N-dimethyl-, hydrochloride.
N,N-Dimethyl-5H-dibenzo[a,d]cycloheptene-D5,-propylamine hydrochloride [6202-23-9].
» Cyclobenzaprine Hydrochloride contains not less than 99.0 percent and not more than 101.0 percent of C20H21N·HCl, calculated on the dried basis.
Packaging and storage— Preserve in well-closed containers.
USP Reference standards 11
USP Cyclobenzaprine Hydrochloride RS Click to View Structure
B: Ultraviolet Absorption 197U
Solution: 15 µg per mL.
Medium: methanol.
Absorptivities at 290 nm, calculated on the dried basis, do not differ by more than 3.0%.
C: A solution (1 in 50) responds to the tests for Chloride 191.
Melting range 741: between 215 and 219, but the range between beginning and end of melting does not exceed 2.
Loss on drying 731 Dry it at 105 to constant weight: it loses not more than 1.0% of its weight.
Residue on ignition 281: not more than 0.1%.
Chromatographic purity— Dissolve 100 mg in methanol, and dilute with methanol to 5.0 mL to obtain the Test solution. Dissolve a suitable quantity of USP Cyclobenzaprine Hydrochloride RS in methanol to obtain a Standard solution having a known concentration of about 20 mg per mL. Dilute a portion of this solution quantitatively and stepwise with methanol to obtain a Diluted standard solution having a concentration of about 100 µg per mL. Apply separate 5-µL portions of the three solutions to the starting line of a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture and previously washed with methanol. Develop the chromatogram in a suitable chamber with a freshly prepared solvent system consisting of a mixture of acetone, toluene, and ammonium hydroxide (75:25:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chamber, air-dry, and view under short-wavelength UV light: the RF value of the principal spot from the Test solution corresponds to that of the Standard solution; and any other spot obtained from the Test solution does not exceed, in size or intensity, the principal spot obtained from the Diluted standard solution (0.5%).
Assay— Dissolve about 400 mg of Cyclobenzaprine Hydrochloride, accurately weighed, in about 80 mL of glacial acetic acid, add 15 mL of mercuric acetate TS, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically, using a platinum ring electrode and a sleeve-type calomel electrode containing 0.1 N lithium perchlorate in glacial acetic acid (see Titrimetry 541). Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 31.19 mg of C20H21N·HCl.
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