Torsemide Compounded Oral Suspension

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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1 DEFINITION

Torsemide Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of torsemide (C₁₆H₂₀N₄O₃S).

 Prepare Torsemide Compounded Oral Suspension 5 mg/mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 〈795〉).

^a Torsemide 10-mg tablets, Camber, Piscataway, NJ.

^b Perrigo, Allegan, MI.

Place the Torsemide Tablets in a suitable container and triturate to a fine powder. Add a small amount of Vehicle and mix well to form a smooth paste. Add a sufficient amount of Vehicle to make the container contents pourable. Transfer the contents stepwise and quantitatively to a calibrated container. Add sufficient Vehicle to bring to final volume. Shake to mix well. Add Sodium Hydroxide (2 N) dropwise to adjust the pH to 8.3.

2 ASSAY

PROCEDURE

Solution A: 10 mM of monobasic potassium phosphate adjusted with phosphoric acid to a pH of 4

Mobile phase: Methanol and Solution A (45:55)

Diluent: 50% methanol in water

Standard solution: Transfer 20 mg of USP Torsemide RS into a 200-mL volumetric flask. Add approximately 150 mL of Diluent and sonicate for 15 min, then dilute with Diluent to volume.

Sample solution: Transfer 1 mL of Oral Suspension into a 50-ml volumetric flask. Add approximately 40 mL of Diluent and sonicate for 15 min, then dilute with Diluent to volume. Filter 1 mL of this solution, discard the first 3 drops, then transfer into an HPLC vial.

Chromatographic system

(See Chromatography (621), System Suitability)

Mode: LC

Detector: UV 280 nm

Column: 4.6-mm x 15-cm; 3-µm packing L1

Temperatures

Autosampler: 4°

Column: 40°

Flow rate: 1.0 mL/min

Injection volume: 10 µl

System suitability

Sample: Standard solution

[NOTE-The retention time for torsemide is about 9.6 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 torsemide (C₁₆H₂₀N₄O₃S) in the portion of Oral Suspension taken:

Result = (r_u /r_s ) × (C_s /C_u ) × 100

r_u = peak response of torsemide from the Sample solution

r_s = peak response of torsemide from the Standard solution

C_s = concentration of USP Torsemide RS in the Standard solution (mg/mL)

C_u = nominal concentration of torsemide in the Sample solution (mg/mL)

Acceptance criteria: 90.0%–110.0%

3 SPECIFIC TESTS

PH (791): 8.0-9.5

4 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Package in tight, light-resistant plastic containers. Store at controlled room temperature or in a refrigerator.

BEYOND-USE DATE: NMT 90 days after the date on which it was compounded when stored in a refrigerator; NMT 30 days after the date on which it was compounded when stored at controlled room temperature.

LABELING: Label it to indicate that it is to be well shaken before use, and to state the Beyond-Use Date.

USP REFERENCE STANDARDS (11)

USP Tarsemide RSA _{(USP 1-May-2020)}