Cysteine Hydrochloride Injection
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
>> Cysteine Hydrochloride Injection is a sterile solution of Cysteine Hydrochloride in Water for Injection. It contains not less than 85.0 percent and not more than 115.0 percent of the labeled amount of C3H7NO2S · HCI · H2O.
Packaging and storage-Preserve in single-dose or multiple-dose containers, preferably of Type I glass.
1 USP REFERENCE STANDARDS (11)-
USP L-Cysteine Hydrochloride RS
2 Identification-
A: To 2 mL of Injection add 3 mL of water, and mix. Add 10 mL of cupric sulfate TS: a bluish-gray precipitate is formed.
B: To 2 mL of Injection add 3 mL of water, and mix. Add 2 mL of 3 N sodium hydroxide and 2 drops of sodium nitroferricyanide solution (1 in 20): a red-purple color is produced, and it rapidly changes to yellow.
BACTERIAL ENDOTOXINS TEST (85). It contains not more than 0.7 USP Endotoxin Unit per mg of cysteine hydrochloride.
PH (791): between 1.0 and 2.5.
Other requirements-It meets the requirements under Injections and Implanted Drug Products (1).
3 Assay-
Standard stock preparation-Dissolve an accurately weighed quantity of USP L-Cysteine Hydrochloride RS in nitrogen-saturated water to obtain a solution having a known concentration of about 1 mg per mL.
Standard preparation-Transfer 20.0 mL of Standard stock preparation to a 200-mL volumetric flask, dilute with nitrogen-saturated 1.0 N sodium hydroxide to volume, and mix.
Assay preparation-Dilute an accurately measured volume of Injection, equivalent to about 250 mg of cysteine hydrochloride, quantitatively and stepwise with nitrogen-saturated 1.0 N sodium hydroxide, to obtain a solution having a concentration of about 0.1 mg per mL.
Procedure-Transfer a suitable amount of Standard preparation to a polarographic cell. With mercury dropping from the electrode, lower the dropping mercury electrode of a polarograph so that the end is submerged in the liquid. Bubble oxygen-free, water-saturated nitrogen through the liquid for 15 minutes. Record the polarogram from -0.2 volt to -1.10 volts, using a saturated calomel electrode as the reference electrode. In a similar manner, record the polarograms obtained using portions of the Assay preparation and of the nitrogen-saturated 1.0 N sodium hydroxide. Determine the height of the diffusion current wave at -0.4 volt. Calculate the quantity, in mg, of C3H7NO2S · HCI · H2O in each mL of the Injection taken by the formula:]
2500(C/V)[(id)U(id)S]
in which C is the concentration, in mg per mL, of USP-Cysteine Hydrochloride RS. In the Standard preparation, V is the volume, in mL, of Injection taken; and(id)U and (id)S are the observed diffusion currents, corrected for the diffusion current of the 0.1 N sodium hydroxide, of the Assay preparation and the Standard preparation, respectively.
