Bretylium Tosylate

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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C₁₈H₂₄BrNO₃S                   414.36

Benzenemethanaminium, 2-bromo-N-ethyl-N,N-dimethyl-, salt with 4-methylbenzenesulfonic acid (1:1). (o-Bromobenzyl)ethyldimethylammonium p-toluenesulfonate CAS RN®: 61-75-6; UNII: 78ZP3YR353.

Bretylium Tosylate contains not less than 98.0 percent and not more than 101.0 percent of C H BrNO S, calculated on the dried basis.

Packaging and storage—Preserve in tight containers. Store at 25°, excursions permitted between 15° and 30°.

USP REFERENCE STANDARDS (11)-USP Bretylium Tosylate RS

1 Identification

Change to read:

A:Spectroscopic Identification Tests (197), Infrared Spectroscopy: 197K. (CN 1-May-2020)

B: The retention time of the major peak in the chromatogram of the Test solution corresponds to that in the chromatogram of the Standard solution, as obtained in the test for Related compounds.

LOSS ON DRYING (731)-Dry it in vacuum at 75° for 2 hours: it loses not more than 3.0% of its weight.

RESIDUE ON IGNITION (281): not more than 0.1%.

2 Related compounds

0.01 M Sodium 1-octanesulfonate solution-Dissolve 1.0814 g of 1-sodium octanesulfonate in 500 mL of water.

Mobile phase-Prepare a mixture of 0.01 M Sodium 1-octanesulfonate solution, acetonitrile, glacial acetic acid, and triethylamine (81:19:2:0.5).

Make adjustments if necessary (see System Suitability under Chromatography (621))

Standard solution-Dissolve an accurately weighed quantity of USP Bretylium Tosylate RS in Mobile phase, and dilute quantitatively, and stepwise if necessary, to obtain a solution having a known concentration of about 20 µg per mL.

Test solution-Transfer about 200 mg of Bretylium Tosylate, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.

Chromatographic system (see CHROMATOGRAPHY (621))-The liquid chromatograph is equipped with a 265-nm detector and a 4.6-mm x 25-cm column that contains packing L11. The flow rate is about 1.9 mL per minute. Chromatograph the Standard solution, record the chromatograms, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 3.0%.

Procedure-Separately inject equal volumes (about 30 µL) of the Test solution and the Standard solution into the chromatograph, record the chromatograms, and measure the peak responses. The relative retention times are about 0.25, 0.74, 1.0, 1.27, 1.40 for tosylate ion, o-bromobenzyldimethylamine, bretylium, m-bromobenzyldimethylamine, and p-bromobenzyldimethylamine, respectively. The sum of the responses for all the peaks, excluding those of the bretylium and tosylate peaks, from the Test solution is not more than two times the bretylium response from the Standard solution (2%); and no individual peak response is greater than that of the bretylium peak from the Standard solution (1%).

Assay-Dissolve about 300 mg of Bretylium Tosylate, accurately weighed, in 50 mL of dioxane in a conical flask. Add 2 drops of crystal violet TS, and titrate with 0.025 N perchloric acid in dioxane to a blue-green endpoint. Perform a blank determination (see Titrimetry (541)), and make any necessary correction. Each mL of 0.025 N perchloric acid is equivalent to 10.36 mg of C₁₈H₂₄BrNO₃S.