Captopril 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

Captopril Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of captopril (C₉H₁₅NO₃S).

Prepare Captopril Compounded Oral Suspension 0.75 mg/mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 〈795〉).

Place the required number of tablets in a suitable mortar and comminute to a fine powder, or use Captopril powder. Add 10 mL of Vehicle, and mix to form a uniform paste. Add the Vehicle in small portions, and mix thoroughly after each addition. Transfer the contents of the mortar, stepwise and quantitatively, to a calibrated bottle. Add sufficient Vehicle to bring to final volume, and mix well.

2 ASSAY

2.1 Procedure

Mobile phase: Methanol and water (55:45) containing 0.5 mL/L of phosphoric acid. Filter, and degas.

Standard solution: 7.5 μg/mL of USP Captopril RS

Sample solution: Agitate the container of Oral Suspension for 30 min on a rotating mixer, remove a 5-mL sample, and store in a clear glass vial at −70° until analyzed. At the time of analysis, remove the sample from the freezer, allow it to reach room temperature, and mix with a vortex mixer for 30 s. Pipet 1.0 mL of the sample into a 100-mL volumetric flask, and dilute with Mobile phase to volume.

2.2 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 220 nm

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

Flow rate: 1 mL/min

Injection volume: 20 μL

2.3 System suitability

Sample: Standard solution

[Note—The retention time for captopril is about 5.0 min.]

2.4 Suitability requirements

Relative standard deviation: NMT 0.9% for replicate injections

2.5 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of captopril (C₉H₁₅NO₃S) in the portion of Oral Suspension taken:

Result = (r_U/r_S) x (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 USP Captopril RS in the Standard solution (μg/mL)

C_u = nominal concentration of captopril in the Sample solution (μg/mL)

Acceptance criteria: 90.0%–110.0%

3 SPECIFIC TESTS

pH 〈791〉: 3.8–4.3

4 ADDITIONAL REQUIREMENTS

Packaging and Storage: Package in tight, light-resistant containers. Store in a refrigerator.

Beyond-Use Date: NMT 7 days after the date on which it was compounded when stored in a refrigerator

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 Captopril RS