Potassium Phosphates Compounded Injection

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

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

DOWNLOAD PDF HERE

1 DEFINITION

Potassium Phosphates Compounded Injection contains NLT 95.0% and NMT 105.0% of the labeled amount of monobasic potassium phosphate (KH₂PO₄) and dibasic potassium phosphate (K₂HPO₄). It contains no bacteriostat or other preservative.

Prepare Potassium Phosphates Compounded Injection containing 3 mM/mL of phosphorus and 4.4 mEq/mL of potassium as follows (see Pharmaceutical Compounding-Sterile Preparations (797)).

Dissolve the Dibasic Potassium Phosphate (anhydrous) in 50 mL of Sterile Water for Injection. Dissolve the Monobasic Potassium Phosphate (anhydrous) in the solution and then bring to final volume with Sterile Water for Injection. [NOTE-May need to heat to 77° to fully dissolve. If heating is required, allow to reach room temperature prior to passing through a filter.] Pass through a filter of 1.2-µm pore size to remove particulate matter and sterilize by autoclave.

2 ASSAY

Change to read:

2.1 PROCEDURE FOR POTASSIUM

Mobile phase: 8 mM methanesulfonic acid

Standard solution: 0.050 mg/mL of potassium prepared with USP Dibasic Potassium Phosphate RS and water

Sample solution: Transfer 74 µL of Injection to a 250-mL volumetric flask and dilute with water to volume.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: Conductivity

Column: 4-mm (ERR 1-Sep-2024) x 25-cm; packing L97

Column temperature: 30°

Flow rate: 1.0 mL/min

Injection volume: 10 µL

System suitability

Sample: Standard solution

[NOTE-The retention time for potassium is about 5.1 min.]

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0% for replicate injections

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of potassium (K) in the portion of Injection taken:

Result = (r_U/r_S) x (C_S/C_U) x 100

r_U = peak response of potassium from the Sample solution

r_S = peak response of potassium from the Standard solution

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

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

Acceptance criteria: 95.0%-105.0%

Change to read:

2.2 PROCEDURE FOR PHOSPHATE

Mobile phase: 40 mM sodium hydroxide

Standard solution: 0.230 mg/mL of phosphate prepared from USP Dibasic Potassium Phosphate RS in water

Sample solution: Transfer 0.2 mL of Injection to a 250-mL volumetric flask and dilute with water to volume.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: Conductivity

Column: 4-mm (ERR 1-Sep-2024) x 25-cm; packing L103

Column temperature: 30°

Flow rate: 1.0 mL/min

Injection volume: 10 µL

System suitability

Sample: Standard solution

[NOTE-The retention time for phosphorus is about 5.4 min.]

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0% for replicate injections

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of phosphate (PO₄) in the portion of Injection taken:

Result = (r_U/r_S) x (C_S/C_U) x 100

r_U = peak response of phosphate from the Sample solution

r_S = peak response of phosphate from the Standard solution

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

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

Acceptance criteria: 95.0%-105.0%

3 SPECIFIC TESTS

3.1 PH (791)

6.3-7.3

3.2 STERILITY TESTS (71)

Meets the requirements

3.3 BACTERIAL ENDOTOXINS TEST (85)

NMT 1.10 USP Endotoxin Units/mg of potassium phosphates

3.4 PARTICULATE MATTER IN INJECTIONS (788)

Meets the requirements

4 ADDITIONAL REQUIREMENTS

4.1 PACKAGING AND STORAGE

Package in single-dose glass containers. Store at controlled room temperature.

4.2 BEYOND-USE DATE

In the absence of performing and completing a sterility and endotoxin test, the storage conditions in Pharmaceutical Compounding - Sterile Preparations (797), 14.3 Establishing a BUD for a CSP apply. After successful completion of sterility and endotoxin testing, NMT 120 days after the date on which it was compounded when stored at controlled room temperature.

4.3 LABELING

Label it to state the Beyond-Use Date. The label states the potassium content in terms of milliequivalents in a given volume, and states also the elemental phosphorus content in terms of millimoles in a given volume. Label it not for direct injection.

4.4 USP REFERENCE STANDARDS (11)

USP Dibasic Potassium Phosphate RS