Cycloserine

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

DOWNLOAD PDF HERE

C₃H₆N₂O₂         102.09

3-Isoxazolidinone, 4-amino-, (R)-.

(+)-4-Amino-3-isoxazolidinone CAS RN^®: 68-41-7; UNII: 95IK5KI84Z.

>> Cycloserine has a potency of not less than 900 µg of C₃H₆N₂O₂  per mg.

Packaging and storage-Preserve in tight containers.

1 USP REFERENCE STANDARDS (11)-

USP Cycloserine RS

Identification-Dissolve about 1 mg in 10 mL of 0.1 N sodium hydroxide. To 1 mL of the resulting solution add 3 mL of 1 N acetic acid and 1 mL of a mixture, prepared 1 hour before use, of equal parts of sodium nitroprusside solution (1 in 25) and 4 N sodium hydroxide: a blue color gradually develops.

Condensation products-Its absorptivity (see Ultraviolet-Visible Spectroscopy (857)) at 285 nm, determined in a 0.1 N sodium hydroxide solution containing 0.40 mg per mL is not more than 0.80.

SPECIFIC ROTATION (781S): between 108° and 114".

Test solution: 50 mg per mL, in 2 N sodium hydroxide.

CRYSTALLINITY (695): meets the requirements.

PH (791): between 5.5 and 6.5, in a solution (1 in 10).

LOSS ON DRYING (731)-Dry about 100 mg in a capillary-stoppered bottle in vacuum at 60° for 3 hours: it loses not more than 1.0% of its weight.

RESIDUE ON IGNITION (281): not more than 0.5%, the charred residue being moistened with 2 mL of nitric acid and 5 drops of sulfuric acid.

2 Assay-

pH 6.8 Phosphate buffer-Prepare as directed in Buffer Solutions under Solutions in the section Reagents, Indicators, and Solutions.

Mobile phase-Dissolve 0.5 g of sodium 1-decanesulfonate in 800 mL of water, add 50 mL of acetonitrile and 5 mL of glacial acetic acid, and mix. Adjust with 1 N sodium hydroxide to a pH of 4.4. Filter, and degas. Make adjustments if necessary (see System Suitability under Chromatography (621)).

Standard preparation-Quantitatively dissolve an accurately weighed quantity of USP Cycloserine RS in pH 6.8 Phosphate buffer to obtain a solution having a known concentration of about 0.4 mg per mL.

Assay preparation-Transfer about 20 mg of Cycloserine, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with pH 6.8 Phosphate buffer to volume, and mix.

Chromatographic system (see CHROMATOGRAPHY (621)) -The liquid chromatograph is equipped with a 219-nm detector and a 4.6-mm x 25-cm column that contains 5-µm packing L1. The flow rate is about 1 mL per minute. The column temperature is maintained at about 30°.

Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the tailing factor is not more than 1.8; and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure-Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the peak responses for cycloserine. Calculate the quantity, in µg, of C₃H₆N₂O₂  in each mg of Cycloserine taken by the formula:

                50000(C / W)(r_U/r_S)

in which C is the concentration, in mg per mL, of USP Cycloserine RS in the Standard preparation; W is the quantity, in mg, of Cycloserine taken to prepare the Assay preparation; and r_U and r_S are the peak responses for cycloserine obtained from the Assay preparation and the Standard preparation, respectively.