Calcitriol 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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Calcitriol Injection is a sterile solution of Calcitriol. It contains an amount of Calcitriol equivalent to not less than 90.0 percent and not more than 115.0 percent of the labeled amount of calcitriol (C₂₇H₄₄O₃). It contains no antimicrobial agents.

Packaging and storage—Preserve in single-dose containers, preferably of Type I glass, protected from light. Store at controlled room temperature.

USP Reference standards 〈11〉

USP Calcitriol Solution RS

Identification—The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

Bacterial Endotoxins Test 〈85〉 —It contains not more than 100 USP Endotoxin Units per μg of calcitriol.

pH 〈791〉: between 5.9 and 8.0, determined on a portion to which, if necessary, 0.30 mL of saturated potassium chloride solution has been added for each 100 mL of Injection.

Particulate Matter in Injections 〈788〉 : meets the requirements for small-volume injections.

Other requirements—It meets the requirements under Injections and Implanted Drug Products 〈1〉.

Assay

[Note—Avoid unnecessary exposure of solutions to light or air.]

Mobile phase—Prepare a filtered and degassed mixture of methanol and water (74:26). Make adjustments if necessary (see System Suitability under Chromatography 〈621〉) so that the retention time for calcitriol is not less than 20 minutes.

Standard preparation—Transfer 3.0 mL of USP Calcitriol Solution RS, equilibrated to room temperature, to a container; add 3.0 mL of water; and mix.

Assay preparation—Transfer an accurately measured volume of Injection, equivalent to about 3 μg of calcitriol, to a container; add a sufficient amount of water to dilute to a total volume of 3.0 mL; add 3.0 mL of methanol; and mix.

Chromatographic system (see Chromatography 〈621〉)—The liquid chromatograph is equipped with a 264-nm detector, a 4.6-mm × 4.5-cm guard column that contains 5-μm packing L1, and a 4.6-mm × 7.5-cm analytical column that contains 3-μm packing L1. The flow rate is about

1 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 2.0%.

Procedure—Separately inject equal volumes (about 100 μL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in μg, of calcitriol (C₂₇H₄₄O₃) in each mL of the Injection taken by the formula:

C(r_U/r_S)

in which C is the concentration, in μg per mL, of calcitriol in the USP Calcitriol Solution RS; and r_U and r_S are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.