Fluoxymesterone

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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C₂₀H₂₉ FO₃ 336.44

Androst-4-en-3-one, 9-fluoro-11,17-dihydroxy-17-methyl-, (11β,17β)-.

9-Fluoro-11β,17β-dihydroxy-17-methylandrost-4-en-3-one CAS RN®: 76-43-7; UNII: 9JU12S4YFY.

Fluoxymesterone contains not less than 97.0 percent and not more than 102.0 percent of C₂₀H₂₉ FO₃, calculated on the dried basis.

1 Packaging and storage

Preserve in well-closed containers, protected from light.

USP Reference standards 〈11〉

USP Fluoxymesterone RS

2 Identification

Change to read:

A: Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K (CN 1-May-2020) —If a difference appears, dissolve portions of both the test specimen and the USP Reference Standard in dehydrated alcohol, evaporate the solutions to dryness, and repeat the test on the residues.

Change to read:

B: Spectroscopic Identification Tests 〈197〉, Ultraviolet-Visible Spectroscopy: 197U (CN 1-May-2020)

Solution: 10 μg per mL.

Medium: alcohol.

Absorptivities at 242 nm do not differ by more than 2.5%.

Specific rotation 〈781S〉: between +104° and +112°.

Test solution: 10 mg per mL, in alcohol.

Loss on drying 〈731〉 - Dry it at 105° for 3 hours: it loses not more than 1.0% of its weight.

3 Chromatographic purity

Solution A - Prepare a filtered and degassed mixture of methanol and water (55:45).

Solution B - Use filtered and degassed methanol.

Mobile phase - Use variable mixtures of Solution A and Solution B as directed for Chromatographic system.

Blank solution - Use Solution B.

System suitability solution - Dilute a volume of the Test solution quantitatively, and stepwise if necessary, with methanol to obtain a solution having a concentration of about 5 μg of fluoxymesterone per mL.

Test solution - Prepare a solution of Fluoxymesterone in Solution B containing about 0.5 mg per mL.

Chromatographic system (see Chromatography 〈621〉) - The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 25-cm column that contains packing L1. The column temperature is maintained at 40°. The flow rate is 1.0 mL per minute. The chromatograph is programmed as follows.

Chromatograph the Test solution, and record the peak responses as directed for Procedure: the column efficiency is not less than 15,000 theoretical plates. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the signal-to-noise ratio for the fluoxymesterone peak is not less than 100.

Procedure - Separately inject equal volumes (about 5 μL) of the Blank solution and the Test solution into the chromatograph, record the chromatograms, and measure the areas for any peaks that do not appear in the Blank solution that have an area equal to or greater than 0.1% of the fluoxymesterone peak. Calculate the percentage of each impurity in the portion of Fluoxymesterone taken by the formula:

100(r_i/r_i)

in which r_i is the peak response for each impurity; and r_i is the sum of the responses of all the peaks: not more than 1.0% of any individual impurity is found; and not more than 2.0% of total impurities is found.

4 Assay

Internal standard solution - Dissolve Methylprednisolone in a mixture of chloroform and methanol (95:5) to obtain a solution containing about 200 μg per mL.

Mobile phase - Prepare a solution containing butyl chloride, water-saturated butyl chloride, tetrahydrofuran, methanol, and glacial acetic acid (475:475:70:35:30).

Standard preparation - Dissolve an accurately weighed quantity of USP Fluoxymesterone RS in Internal standard solution to obtain a solution having a known concentration of about 0.25 mg per mL.

Assay preparation - Dissolve about 25 mg of Fluoxymesterone, accurately weighed, in 100.0 mL of Internal standard solution to obtain a solution having a concentration of about 0.25 mg per mL.

Procedure - Inject equal volumes of the Assay preparation and the Standard preparation into a suitable high-pressure liquid chromatograph (see Chromatography 〈621〉) of the general type equipped with a detector for monitoring UV light at 254 nm, equipped with a suitable recorder, and capable of providing column pressure up to about 2000 psi. The instrument contains a 4-mm × 30-cm stainless steel column that contains packing L3. In a suitable chromatogram, the resolution, R, between fluoxymesterone and the internal standard is not less than 3.0; and the relative standard deviation of the peak response ratios of four replicate injections of the Standard preparation is not more than 2.0%.

Calculate the quantity, in mg, of C₂₀H₂₉ FO₃ in the portion of Fluoxymesterone taken by the formula:

100C(R_U/R_S)

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