Butorphanol Tartrate
(bue tor' fa nol tar' trate).
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C21H29NO2·C4H6O6 477.55

Morphinan-3,14-diol, 17-(cyclobutylmethyl)-, (–)-, [S-(R*,R*)]-2,3-dihydroxybutanedioate (1:1) (salt).
(–)-17-(Cyclobutylmethyl)morphinan-3,14-diol d-(–)-tartrate (1:1) (salt) [58786-99-5].
» Butorphanol Tartrate contains not less than 98.0 percent and not more than 102.0 percent of C21H29NO2·C4H6O6, calculated on the anhydrous basis.
Packaging and storage— Preserve in tight containers. Store at 25, excursions permitted between 15 and 30.
USP Reference standards 11
USP Butorphanol Tartrate RS Click to View Structure
B: The RF value of the principal spot in the chromatogram of the Test preparation corresponds to that in the chromatogram of the Standard preparation, as obtained for test A in the Chromatographic purity test.
Specific rotation 781S: between –60 and –66.
Test solution: 4 mg per mL, in methanol.
Water, Method I 921: not more than 2.0%.
Residue on ignition 281: not more than 0.1%.
Chromatographic purity—
method a (Thin-Layer Chromatography)—
Standard solution— Prepare a solution in methanol containing 1 mg of USP Butorphanol Tartrate RS per mL.
Test solution— Transfer 100 mg of Butorphanol Tartrate to a 10-mL volumetric flask. Dissolve in methanol, dilute with methanol to volume, and mix.
Iodoplatinate spray reagent— Prepare a 1 in 10 solution of chloroplatinic acid in water. To 0.5 mL of this solution add 33 mL of water and 1 g of potassium iodide to obtain the spray reagent. Prepare fresh daily.
Procedure— Apply 50 µL of the Test solution, containing 500 µg of butorphanol tartrate, and 5 µL and 10 µL of the Standard solution, containing 5 µg and 10 µg of USP Butorphanol Tartrate RS, respectively, about 2 cm apart to a line parallel to and about 2 cm from the bottom of a thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Place the plate in a developing chamber containing, and equilibrated with, a mixture of chloroform, methanol, benzene, and ammonium hydroxide (85:25:20:5). Develop the chromatogram until the solvent front has moved about 10 cm above the line of application. Remove the plate, mark the solvent front, and allow the solvent to evaporate. Spray the plate with Iodoplatinate spray reagent. Estimate the percentage of the impurities present in the Test solution by comparing the intensities of secondary spots, if present, with the intensities of the principal spots obtained from the chromatograms of the Standard solution. The sum of the impurities observed is not greater than 2.0%.
method b (Gas Chromatography)— Dissolve a suitable quantity of Butorphanol Tartrate in methanol to obtain a solution containing about 10 mg per mL. Inject 1 µL of this solution into a suitable gas chromatograph equipped with a flame-ionization detector and a 1.8-m × 4-mm glass column containing 3% liquid phase G3 on support S1AB. The temperatures of the injection port, column, and detector are maintained at about 280, 250, and 290, respectively. The carrier gas is nitrogen. Record a 30-minute chromatogram. Preferably using an electronic integrator, determine the areas of all peaks in the chromatogram excluding the area of the solvent. In a suitable chromatogram, the retention time for the alpha isomer of butorphanol tartrate is 1.2 relative to 1.0 for butorphanol tartrate; and the retention time of butorphanol tartrate is not less than 15 minutes. Calculate the percentage of synthesis precursors in the test specimen by the formula:
100AV / AS
in which AV is the sum of the areas of all minor peaks; and AS is the sum of the areas of the major and minor peaks. The limit is 2.0%.
Assay— Dissolve about 500 mg of Butorphanol Tartrate, accurately weighed, in 75 mL of glacial acetic acid. Add crystal violet TS, and titrate with 0.1 N perchloric acid VS. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 47.76 mg of C21H29NO2·C4H6O6.
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