Spironolactone Compounded Oral Suspension, Veterinary

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

Spironolactone Compounded Oral Suspension, Veterinary contains NLT 90.0% and NMT 110.0% of the labeled amount of spironolactone (C₂₄H₃₂O₄S).

Prepare Spironolactone Compounded Oral Suspension, Veterinary 25 mg/mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 〈795〉).

^a Spironolactone 25-mg tablets, Mylan, Morgantown, WV.

^b Paddock Laboratories, Minneapolis, MN.

Calculate the required quantity of each ingredient for the total amount to be prepared. Place the required number of tablets in a suitable mortar, and comminute to a fine powder with a pestle. Add the Vehicle in small portions, and triturate to make a smooth paste. Add increasing volumes of the Vehicle to make a spironolactone liquid that is pourable. Transfer the contents of the mortar, stepwise and quantitatively, to a calibrated bottle. Add enough of the Vehicle to bring to final volume, and mix well.

2 ASSAY

PROCEDURE

Mobile phase: Acetonitrile and 20 mM dibasic ammonium phosphate (55:45). Filter and degas.

Diluent: Acetonitrile and water (50:50)

Standard stock solution: 1.0 mg/mL of USP Spironolactone RS in Diluent

Standard solution: Pipet 2.5 mL of the Standard stock solution to a 10-mL volumetric flask, and dilute with Diluent to volume to obtain a solution with a nominal concentration of 0.25 mg/mL.

Sample solution: Shake each bottle of Oral Suspension, Veterinary thoroughly by hand. Pipet 1.0 mL of the Oral Suspension, Veterinary into a 100-mL volumetric flask, and dilute with Diluent to volume to obtain a solution with a nominal concentration of 0.25 mg/mL.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 4.6-mm × 25-cm; 5-µm packing L1

Flow rate: 1.0 mL/min

Injection volume: 20 µL

System suitability

Sample: Standard solution

[NOTE—The retention time for spironolactone is about 10.4 min.]

Suitability requirements

Column efficiency: NLT 9000 theoretical plates

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 spironolactone (C24H32O4S) in the portion of Oral Suspension, Veterinary taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

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

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

Acceptance criteria: 90.0%–110.0%

3 SPECIFIC TESTS

PH 〈791〉: 3.7–4.9

4 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Package in tight, light-resistant containers. Store at 2°–8° or 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. Label to indicate that it is for veterinary use only.

BEYOND-USE DATE: NMT 60 days after the date on which it was compounded, when stored at 2°–8° or controlled room temperature

USP REFERENCE STANDARDS 〈11〉

USP Spironolactone RS