Doxercalciferol

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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1α-Hydroxyvitamin D₂;

1α-Hydroxyergocalciferol;

9,10-Secoergosta-5,7,10(19),22-tetraene-1,3-diol, (1α,3β,5Z,7E,22E)-;

(5Z,7E,22E)-9,10-Secoergosta-5,7,10(19),22-tetraene-1α,3β-diol CAS RN^®: 54573-75-0.

1 DEFINITION

Doxercalciferol contains NLT 98.0% and NMT 102.0% of doxercalciferol (C₂₈H₄₄O₂), calculated on the dried basis.

[CAUTION-Great care should be taken in handling Doxercalciferol, because it is a potentially cytotoxic agent.]

2 IDENTIFICATION

Change to read:

A. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197K (CN 1-MA-2020)

B. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

PROCEDURE

[NOTE-Protect doxercalciferol solutions from light.]

Solution A: Water

Solution B: Acetonitrile

Mobile phase: See Table 1. Return to original conditions and re-equilibrate the system for 5 min.

Standard solution: 1.0 mg/mL of USP Doxercalciferol RS in acetonitrile. Use sonication to dissolve if necessary.

System suitability solution: Heat a portion of the Standard solution at 40° for 1 h to obtain at least 0.1%-0.2% of pre-doxercalciferol.

Sample solution: 1.0 mg/mL of Doxercalciferol in acetonitrile. Use sonication to dissolve if necessary.

[NOTE-Doxercalciferol solutions are stable for at least 9 h when stored at room temperature, and up to 7 days when stored at 5"]

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 265 nm

Column: 4.6-mm x 15-cm; 3-µm packing LT

Column temperature: 35°

Flow rate: 1.7 mL/min

Injection volume: 5 µL

System suitability

Samples: Standard solution and System suitability solution

[NOTE-The relative retention times for pre-doxercalciferol and doxercalciferol are 0.94 and 1.0, respectively.]

Suitability requirements

Resolution: NLT 2.0 between pre-doxercalciferol and doxercalciferol, System suitability solution

Tailing factor: 0.7-1.3, Standard solution

Relative standard deviation: NMT 0.73%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of doxercalciferol (CHO) in the portion of Doxercalciferol taken:

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

r_U = peak response of doxercalciferol from the Sample solution

r_S = peak response of doxercalciferol from the Standard solution

C_S = concentration of USP Doxercalciferol RS in the Standard solution (mg/mL)

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

Acceptance criteria: 98.0%-102.0% on the dried basis

4 IMPURITIES

ORGANIC IMPURITIES

[NOTE-Protect doxercalciferol solutions from light.]

Solution A, Solution B, and Chromatographic system: Proceed as directed in the Assay.

Mobile phase: See Table 2. Return to original conditions and re-equilibrate the system for 5 min.

Standard stock solution: 4.0 mg/mL of USP Doxercalciferol RS. Dissolve first in ethyl acetate using about 20% of the final volume with sonication in an ice-water bath, if necessary, and dilute with acetonitrile to volume.

Standard solution: 0.004 mg/mL of USP Doxercalciferol RS in acetonitrile from the Standard stock solution

System suitability solution: Heat a portion of the Standard stock solution at 40 deg for 1 h or let it stand at room temperature for about 4-6 h, to obtain at least 0.1% + (- 0.2)% of pre-doxercalciferol

Sample solution: 4.0 mg/ml. of Doxercalciferol. Dissolve first in ethyl acetate using about 20% of the final volume with sonication in an ice-water bath, if necessary, and dilute with acetonitrile to volume. [NOTE-The Sample solution should be prepared fresh before injection and injected within 5 min of completing its preparation.]

System suitability

Sample: System suitability solution

Suitability requirements

Resolution: NLT 2.0 between pre-doxercalciferol and doxercalciferol

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each individual impurity in the portion of Doxercalciferol taken:

Result = (r_U/(r_{​​​​​​​S}) × (C_S /C_U) × 100

r_U = peak response of each impurity from the Sample solution 

r_S = peak response of doxercalciferol from the Standard solution 

C_S = concentration of USP Doxercalciferol RS in the Standard solution (mg / mL)

C_U = concentration of Doxercalciferol in the Sample solution 

Acceptance criteria: See Table 3. Disregard any peak observed in the blank.

^a (5E,7E,22E)-9,10-Secoergosta-5,7,10(19),22-tetraene-10,3β-diol.

^b If possible from manufacturing process.

^c (57,7E,22E)-9,10-Secoergosta-5,7,10(19),22-tetraene-1B,3B-diol.

^d (57,7E)-9,10-Secoergosta-5,7,10(19)-triene-10,3ẞ-diol.

5 SPECIFIC TESTS

LOSS ON DRYING

(See Thermal Analysis (891).)

Analysis: Determine the percentage of volatile substances by thermogravimetric analysis on an appropriately calibrated instrument, using 5-10 mg of Doxercalciferol. Heat the specimen under test at a rate of 5"/min in a stream of nitrogen at a flow rate of about 40 mL/min. Record the thermogram from ambient temperature to 150°.

Acceptance criteria: NMT 0.50%

OPTICAL ROTATION (781S), Procedures. Specific Rotation

Sample solution: 10 mg/ml, in alcohol

Acceptance criteria: +45° to +52°

MICROBIAL ENUMERATION TESTS (61) and TESTS FOR SPECIFIED MICROORGANISMS (62): [NOTE-This requirement applies only if the drug substance is

intended for use in the manufacture of parenteral dosage forms.] The total aerobic microbial count is NMT 103 cfu/g, and the total combined yeasts and molds count is NMT 102 cfu/g.

ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight, light-resistant containers. Store at a lowered temperature not exceeding 8°.