Chlorothiazide Sodium for Injection
C7H5ClN3NaO4S2 317.71

2H-1,2,4-Benzothiadiazine-7-sulfonamide, 6-chloro-, 1,1-dioxide, monosodium salt.
6-Chloro-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide monosodium salt [7085-44-1].
» Chlorothiazide Sodium for Injection is a sterile, freeze-dried mixture of Chlorothiazide Sodium (prepared by the neutralization of Chlorothiazide with the aid of Sodium Hydroxide) and Mannitol. It contains chlorothiazide sodium (C7H5ClN3NaO4S2) equivalent to not less than 93.0 percent and not more than 107.0 percent of the labeled amount of chlorothiazide (C7H6ClN3O4S2).
Packaging and storage— Preserve in Containers for Sterile Solids as described under Injections 1.
USP Reference standards 11
USP Chlorothiazide RS Click to View Structure
USP Endotoxin RS
Constituted solution— At the time of use, it meets the requirements for Constituted Solutions under Injections 1.
Identification, Ultraviolet Absorption 197U
Solution: 10 µg per mL.
Medium: sodium hydroxide solution (1 in 250).
Bacterial endotoxins 85 It contains not more than 0.3 USP Endotoxin Unit per mg of chlorothiazide sodium.
Uniformity of dosage units 905: meets the requirements.
pH 791: between 9.2 and 10.0, in a solution prepared as directed in the labeling.
Other requirements— It meets the requirements under Injections 1.
Assay— Transfer an accurately weighed portion of Chlorothiazide Sodium for Injection, equivalent to about 500 mg of chlorothiazide, to a 1000-mL volumetric flask, add sodium hydroxide solution (1 in 250) to volume, and mix. Transfer 5.0 mL of this solution to a 250-mL volumetric flask, dilute with sodium hydroxide solution (1 in 250) to volume, and mix. Concomitantly determine the absorbances of this solution and a Standard solution of USP Chlorothiazide RS in the same medium having a known concentration of about 10 µg per mL in 1-cm cells at the wavelength of maximum absorbance at about 292 nm, with a suitable spectrophotometer, using sodium hydroxide solution (1 in 250) as the blank. Calculate the quantity, in mg, of C7H6ClN3O4S2 in the portion of Chlorothiazide Sodium for Injection taken by the formula:
50C(AU / AS)
in which C is the concentration, in µg per mL, of USP Chlorothiazide RS in the Standard solution; and AU and AS are the absorbances of the assay solution and the Standard solution, respectively.
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