Flurazepam Hydrochloride Capsules

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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Flurazepam Hydrochloride Capsules contain not less than 90.0 percent and not more than 110.0 percent of the labeled amount of flurazepam hydrochloride (C₂₁H₂₃ClFN₃O · 2HCl).

Packaging and storage—Preserve in tight, light-resistant containers.

USP Reference standards 〈11〉—

USP Flurazepam Hydrochloride RS

Identification—

A: Dissolve a portion of Capsules, equivalent to about 30 mg of flurazepam hydrochloride, in 10 mL of methanol, filter, and proceed as directed for Identification test C under Flurazepam Hydrochloride.

B: The retention time of the major peak for flurazepam hydrochloride in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

C: Capsules meet the requirements under Identication—Organic Nitrogenous Bases 〈181〉.

Dissolution 〈711〉—

Medium: 0.01 N hydrochloric acid; 900 mL.

Apparatus 1: 100 rpm.

Time: 20 minutes.

Standard solution—Prepare a solution of USP Flurazepam Hydrochloride RS having an accurately known concentration similar to the concentration of the solution under test. Pipet 5 mL of this solution to a 10-mL volumetric ask, and dilute with 1% ammonium acetate to volume.

Test solution—Pipet 5 mL of a filtered portion of the solution under test into a 10-mL volumetric ask, and dilute with 1% ammonium acetate to volume.

Procedure—Determine the amount of C₂₁H₂₃ClFN₃O · 2HCl dissolved, using the Chromatographic system as set forth in the Related compounds test under Flurazepam Hydrochloride.

Tolerances—Not less than 75% (Q) of the labeled amount of C₂₁H₂₃ClFN₃O · 2HCl is dissolved in 20 minutes.

Uniformity of dosage units 〈905〉: meet the requirements.

Assay—

Mobile phase, System suitability solution, and Chromatographic system—Prepare as directed for Related compounds under Flurazepam Hydrochloride.

Standard preparation—Dissolve an accurately weighed quantity of USP Flurazepam Hydrochloride RS in methanol, and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution having a known concentration of about 0.15 mg per mL. Prepare fresh daily.

Assay preparation—[Note—Prepare fresh daily.] Weigh and mix the contents of not fewer than 20 Capsules. Transfer an accurately weighed portion of the Capsule contents, equivalent to about 30 mg of flurazepam hydrochloride, to a 200-mL volumetric ask. Add 40 mL of methanol, and shake by mechanical means for 10 minutes. Add 10 mL of 1% ammonium acetate, and shake by mechanical means for 5 minutes. Dilute with Mobile phase to volume, mix and sonicate for 2 minutes, and filter.

Procedure—Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of flurazepam hydrochloride (C₂₁H₂₃ClFN₃O · 2HCl) in the portion of Capsules taken by the formula:

200C(r_U /r_S )

in which C is the concentration, in mg per mL, of USP Flurazepam Hydrochloride RS in the Standard preparation; and r_U and r_S are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.