Identification—
Dilute 2 mL of Injection with water to 25 mL: the UV absorption spectrum of the solution so obtained exhibits maxima and minima at the same wavelengths as that of a similar solution of
USP Dihydroergotamine Mesylate RS, concomitantly measured.
Assay—
Reagent preparation—
Dissolve 250 mg of p-dimethylaminobenzaldehyde in a cooled mixture of 130 mL of sulfuric acid and 70 mL of water, and add 0.40 mL of ferric chloride solution (1 in 20).
Standard preparation—
Dissolve in tartaric acid solution (1 in 100) a suitable quantity of
USP Dihydroergotamine Mesylate RS, accurately weighed, and dilute quantitatively and stepwise with the same solvent to obtain a solution having a known concentration of about 50 µg per mL.
Assay preparation—
Transfer an accurately measured volume of Injection, equivalent to about 5 mg of dihydroergotamine mesylate, to a 100-mL volumetric flask, dilute with tartaric acid solution (1 in 100) to volume, and mix.
Procedure—
Transfer 5.0 mL each of the
Standard preparation, the
Assay preparation, and tartaric acid solution (1 in 100) to provide the blank, to separate 50-mL conical flasks. Add 10.0 mL of the
Reagent preparation to each, shake, and allow to stand for 30 minutes. Concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 585 nm, with a suitable spectrophotometer, using the blank to set the instrument. Calculate the quantity, in mg, of C
33H
37N
5O
5·CH
4O
3S in each mL of the Injection taken by the formula:
(0.1C / V)(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Dihydroergotamine Mesylate RS in the
Standard preparation, V is the volume, in mL, of Injection taken, and
AU and
AS are the absorbances of the solutions from the
Assay preparation and the
Standard preparation, respectively.
85
—
It contains not more than 175.0 USP Endotoxin Units per mg of dihydroergotamine mesylate.