Packaging and storage—
Preserve in single-unit double-ended glass ampuls or in low-density polyethylene ampuls.
Labeling—
The label indicates that the Inhalation Solution is not to be used if it contains a precipitate.
Identification—
The UV absorption spectrum of the
Assay preparation prepared as directed in the
Assay exhibits maxima and minima at the same wavelengths as that of a similar solution of
USP Cromolyn Sodium RS, concomitantly measured.
Related compounds—
Apply 10-µL portions of Inhalation Solution and Standard solutions of
USP Cromolyn Sodium RS in a mixture of water, stabilizer-free tetrahydrofuran, and acetone (6:4:1) containing 10 mg per mL (
Standard solution A) and 0.1 mg per mL (
Standard solution B) to a suitable thin-layer chromatographic plate (see
Chromatography 
621
) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of chloroform, methanol, and glacial acetic acid (9:9:2) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Locate the spots on the plate by viewing under short-wavelength UV light: the
RF value of the principal spot obtained from the Inhalation Solution corresponds to that obtained from
Standard solution A. Any spot in the chromatogram obtained from the Inhalation Solution moving ahead of the principal spot is not more intense than the spot in the chromatogram obtained from
Standard solution B (1.0%).
Assay—
pH 7.4 Sodium phosphate buffer
and
Standard preparation—Prepare as directed in the
Assay under
Cromolyn Sodium.
Assay preparation—
Dilute with water an accurately measured volume of Inhalation Solution, equivalent to about 25 mg of cromolyn sodium, to obtain a solution having a concentration of about 250 µg per mL. Pipet 10 mL of this solution into a 100-mL volumetric flask, add 1 mL of pH 7.4 Sodium phosphate buffer, dilute with water to volume, and mix.
Procedure—
Concomitantly determine the absorbances of the
Standard preparation and the
Assay preparation in 1-cm cells at the wavelength of maximum absorbance at about 326 nm, with a suitable spectrophotometer, using a 1 in 100 aqueous solution of
pH 7.4 Sodium phosphate buffer as the blank. Calculate the quantity, in mg, of C
23H
14Na
2O
11 in each mL of the Inhalation Solution taken by the formula:
(C/V)(AU / AS),
in which
C is the concentration, in µg per mL, of
USP Cromolyn Sodium RS in the
Standard preparation; V is the volume, in mL, of Inhalation Solution taken; and
AU and
AS are the absorbances of the solutions obtained from the
Assay preparation and the
Standard preparation, respectively.
