Progesterone

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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C₂₁H₃₀O₂ 314.46 

Pregn-4-ene-3,20-dione. 

Progesterone CAS RN®: 57-83-0; UNII: 4G7DS2Q64Y. 

Progesterone contains not less than 97.0 percent and not more than 103.0 percent of C₂₁H₃₀O₂, calculated on the dried basis. 

Packaging and storage—Preserve in tight, light-resistant containers. Store at 25°, excursions permitted between 15° and 30°. USP Reference standards 〈11〉— 

USP Progesterone RS 

Identification— 

Change to read: 

A: Spectroscopic Identication Tests 〈197〉, Infrared Spectroscopy: 197K  . 

Change to read: 

B: Spectroscopic Identication Tests 〈197〉, Ultraviolet-Visible Spectroscopy: 197U  

Solution: 10 µg per mL. 

Medium: methanol. 

Melting range 〈741〉: between 126° and 131°. It may exist also in a polymorphic modication, melting at about 121°. Specific rotation 〈781S〉: between +175° and +183°. 

Test solution: 20 mg per mL, in dioxane. 

Loss on drying 〈731〉—Dry it in vacuum over silica gel for 4 hours: it loses not more than 0.5% of its weight. 

Assay— 

Mobile phase—Prepare a filtered and degassed mixture of water and isopropyl alcohol (72:28). Make adjustments if necessary (see System Suitability under Chromatography 〈621〉). 

Internal standard solution—Transfer about 66 mg of Methyltestosterone to a 10-mL volumetric flask, add dilute alcohol (85 in 100) to volume, and mix. 

Standard preparation—Dissolve an accurately weighed quantity of USP Progesterone RS in dilute alcohol (85 in 100) to obtain a solution having a known concentration of about 2.5 mg per mL. Transfer 4.0 mL of this solution to a 10-mL volumetric flask, add 1.0 mL of Internal standard solution, then add dilute alcohol (85 in 100) to volume, and mix to obtain a solution having a known concentration of about 1 mg of USP Progesterone RS per mL. 

Assay preparation—Transfer about 10 mg of Progesterone, accurately weighed, to a 10-mL volumetric flask, add 1.0 mL of Internal standard solution, then add dilute alcohol (85 in 100) to volume, and mix. 

Chromatographic system (see Chromatography 〈621〉)—The liquid chromatograph is equipped with a 254-nm detector and a 4-mm × 30-cm column that contains 10-µm packing L1. The flow rate is about 1.5 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the resolution, R, between the analyte and internal standard peaks is not less than 3.5; and the relative standard deviation for replicate injections is not more than 1.5%. 

Procedure—Separately inject equal volumes (5 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. The relative retention times are about 2.0 for progesterone and 1.0 for methyltestosterone. Calculate the quantity, in mg, of C₂₁H₃₀O₂ in the portion of Progesterone taken by the formula: 

10C(R_U/R_S) 

in which C is the concentration, in mg per mL, of USP Progesterone RS in the Standard preparation; and R_U and R_S are the peak response ratios obtained from the Assay preparation and the Standard preparation, respectively.