Estradiol Cypionate Injection

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

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

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1 DEFINITION

Estradiol Cypionate Injection is a sterile solution of Estradiol Cypionate in a suitable oil. It contains NLT 90.0% and NMT 110.0% of the labeled amount of estradiol cypionate (C₂₆H₃₆O₃).

2 IDENTIFICATION

A.

Sulfanilic acid solution: Mix 50 mg of sulfanilic acid with 2 mL of 3 N hydrochloric acid, warm the mixture, then cool it in ice water, and slowly add, with agitation, 0.3 ml of sodium nitrite solution (1 in 10).

Sample solution: Transfer a volume of Injection, equivalent to 5 mg of estradiol cypionate, to a glass-stoppered, 50-ml test tube, and add 30 ml of alcohol.

Analysis: Shake the Sample solution vigorously for 5 min, centrifuge until the two layers have separated, and transfer the alcohol layer, with the aid of a hypodermic syringe, to a 50-ml, beaker. Evaporate on a steam bath to dryness, add 5 ml. of potassium hydroxide solution (1 in 10), and heat on the steam bath for 15 min. Add the Sulfanilic acid solution to the saponified estradiol cypionate.

Acceptance criteria: A red color is produced.

3 ASSAY

PROCEDURE

Mobile phase: 0.8 g/L of ammonium nitrate. Dissolve in 300 mL of water, and combine with 700 mL of acetonitrile

Internal standard solution: 2.0 mg/mL of Testosterone benzoate in tetrahydrofuran

Standard solution: 0.1 mg/mL of USP Estradiol Cypionate RS in tetrahydrofuran, prepared as follows. Transfer 10 mg of USP Estradiol Cypionate RS to a 100-ml volumetric flask, add 10.0 mL of the Internal standard solution, and dilute with tetrahydrofuran to volume. Shake vigorously to dissolve.

Sample solution: Using a "to contain" pipet, transfer an accurately measured volume, in ml, of Injection, equivalent to 10 mg of estradiol cypionate, to a 100-ml, volumetric flask. Rinse the pipet with small portions of tetrahydrofuran, collecting the washings in the volumetric flask. Add 10.0 mL of the Internal standard solution, and dilute with tetrahydrofuran to volume

Chromatographic system

(See Chromatography (621), Sitem Suitability)

Mode: LC

Detector: UV 280 nm

OFF Column: 3.9 mm x 30-cm; packing LT

Flow rate: 1 mL/min

Injection size: 10 μL

System suitability

Sample: Standard solution

Suitability requirements

Resolution: NLT 3.0 between the peaks for estradiol cypionate and the internal standard

Relative standard deviation: NMT 1.5%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of estradiol cypionate (C₂₆H₃₆O₃) in the portion of Injection taken:

Result = (r_U/(r_S) × (C_S /C_U) x 100

r_U = peak response ratio of estradiol cypionate to the internal standard from the Sample solution

r_S = peak response ratio of estradiol cypionate to the internal standard from the Standard solution

C_S = concentration of the Standard solution (mg/mL)

C_U = nominal concentration of the Sample solution (mg/mL)

Acceptance criteria: 90.0%-110.0%

4 SPECIFIC TESTS

INJECTIONS AND IMPLANTED DRUG Products (1) Meets the requirements

5 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in single dose or in multiple-dose, light-resistant containers, preferably of Type I glass.