Methscopolamine Bromide

(meth'' skoe pol' a meen broe' mide).

C18H24BrNO4

398.29

3-Oxa-9-azoniatricyclo[3.3.1.02,4]nonane, 7-(3-hydroxy-1-oxo-2-phenylpropoxy)-9,9-dimethyl-, bromide, [7(S)-(1

]-.

-Epoxy-3

-hydroxy-8-methyl-1

h,5

h-tropanium bromide (–)-tropate

[155-41-9].

» Methscopolamine Bromide contains not less than 97.0 percent and not more than 103.0 percent of C18H24BrNO4, calculated on the dried basis.

Packaging and storage— Preserve in tight, light-resistant containers, and store at room temperature.

USP Reference standards

—

USP Methscopolamine Bromide RS

USP Scopolamine Hydrobromide RS

Identification—

A: Infrared Absorption

197K

B: A solution (1 in 20) meets the requirements of the tests for Bromide

191

Specific rotation

781

: between –21

and –25

, determined in a solution containing 500 mg in each 10 mL.

Loss on drying

731

— Dry it at 105

for 2 hours: it loses not more than 2.0% of its weight.

Residue on ignition

281

: not more than 0.1%.

Chromatographic purity—

Buffer solution, Solution A, Solution B, and Mobile phase— Proceed as directed in the Assay.

Standard solution— Prepare as directed for the Standard preparation in the Assay.

Diluted standard solution— Dilute 5 µL of the Standard solution with Solution A to 10.0 mL.

Test solution— Prepare as directed for the Assay preparation.

Scopolamine hydrobromide solution— Dissolve an accurately weighed quantity of USP Scopolamine Hydrobromide RS in Solution A to obtain a solution having a known concentration of about 0.05 mg per mL.

System suitability solution— Dissolve about 50 mg of USP Methscopolamine Bromide RS in Solution A, add 1.0 mL of Scopolamine hydrobromide solution, and dilute with Solution A to 50.0 mL. This solution contains about 0.1% of scopolamine hydrobromide.

Chromatographic system (see Chromatography

621

)— Proceed as directed in the Assay. In addition, chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the resolution, R, between methscopolamine and scopolamine is not less than 1.5; and the tailing factor for the methscopolamine peak is not more than 2.0.

Procedure— Separately inject equal volumes (about 5 µL) of the Diluted standard solution and the Test solution into the chromatograph, record the chromatogram for four times the retention time of methscopolamine, and measure the responses for the major peaks. Disregard any peak with an area less than that of the methscopolamine peak in the chromatogram obtained from the Diluted standard solution, and disregard any peak that is due to Solution A. Calculate the percentage of each impurity in the portion of Methscopolamine Bromide taken by the formula:

100F(ri / rS)

in which F is the relative response factor for the methscopolamine bromide impurities (see Table 1); ri is the peak area of any impurity obtained from the Test solution; and rS is the peak area of methscopolamine obtained from the chromatogram of the Test solution: not more than 0.1% of any individual impurity is found; and not more than 0.5% of total impurities is found.

Table 1

Name	Relative Retention Time	Relative Response Factor (F)
Tropic acid	0.4	0.4
Scopolamine hydrobromide	0.9	1.0
Methylatropine bromide	1.2	1.0
Apomethscopolamine bromide	3.5	0.6
Any other impurity	—	1.0

Assay—

Buffer solution— Prepare a solution containing 5.16 g of sodium 1-hexanesulfonate monohydrate and 3.40 g of monobasic potassium phosphate in 1000 mL of water, adjust with 1 M phosphoric acid to a pH of 2.8, and mix.

Solution A— Mix 850 mL of Buffer solution and 150 mL of acetonitrile, filter, and degas.

Solution B— Mix 500 mL of Buffer solution and 500 mL of acetonitrile, filter, and degas.

Mobile phase— Use variable mixtures of Solution A and Solution B as directed for Chromatographic system. Make adjustments if necessary (see System Suitability under Chromatography

621

Standard preparation— Dissolve an accurately weighed quantity of USP Methscopolamine Bromide RS in Solution A to obtain a solution having a known concentration of about 1.0 mg per mL.

Assay preparation— Transfer about 50 mg of Methscopolamine Bromide, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with Solution A to volume, and mix.

Chromatographic system (see Chromatography

621

)— The liquid chromatograph is equipped with a 210-nm detector and a 4.6-mm × 10-cm column that contains packing L1. The flow rate is about 3 mL per minute. The column temperature is maintained at 50

. The chromatograph is programmed as follows.

Time (minutes)	Solution A (%)	Solution B (%)	Elution
0–3	100	0	isocratic
3–10	100®85	0®15	linear gradient
10–10.1	85®100	15®0	linear gradient
10.1–13	100	0	re-equilibration

Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation for six replicate injections is not greater than 1%.

Procedure— Separately inject equal volumes (about 5 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the peak area responses. Calculate the quantity, in mg, of C18H24BrNO4 in the portion of Methscopolamine Bromide taken by the formula:

50C(rU / rS)

in which C is the concentration, in mg per mL, of USP Methscopolamine Bromide RS in the Standard preparation; and rU and rS are the peak area responses of methscopolamine obtained from the Assay preparation and the Standard preparation, respectively.

Auxiliary Information— Please check for your question in the FAQs before contacting USP.

Topic/Question	Contact	Expert Committee
Monograph	Elena Gonikberg, Ph.D. Principal Scientific Liaison 1-301-816-8251	(SM32010) Monographs - Small Molecules 3
Reference Standards	RS Technical Services 1-301-816-8129 rstech@usp.org

USP35–NF30 Page 3861

Pharmacopeial Forum: Volume No. 31(2) Page 425