Aspirin Delayed-Release Capsules

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

Aspirin Delayed-Release Capsules contain NLT 93.0% and NMT 107.0% of the labeled amount of aspirin (C₉H₈O₄).

2 IDENTIFICATION

A. The retention time of the aspirin peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

Change to read:

B. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197K _{(CN 1-MAY-2020)}

Sample: Shake a quantity of the contents of Capsules, equivalent to about 500 mg of aspirin, with 10 mL of alcohol for several minutes. Centrifuge the mixture. Pour off the clear supernatant and evaporate it to dryness. Dry the residue under vacuum at 60° for 1 h.

Acceptance criteria: Meet the requirements

3 ASSAY

PROCEDURE

Mobile phase: 2 g/L of sodium 1-heptanesulfonate in a mixture of acetonitrile and water (15:85). Adjust with glacial acetic acid to a pH of 3.4.

Diluent: Acetonitrile and formic acid (99:1)

Standard solution: 0.5 mg/mL of USP Aspirin RS in Diluent

Sample stock solution: Nominally 5 mg/mL of aspirin prepared as follows. Remove, as completely as possible, the contents of NLT 20.

Capsules. Mix the combined contents, and transfer a quantity equivalent to about 100 mg of aspirin to a suitable container. Add 20.0 mL of Diluent and about 10 glass beads. Shake vigorously for about 10 min, and centrifuge.

Sample solution: Nominally 0.5 mg/mL of aspirin in Diluent from Sample stock solution

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 280 nm

Column: 4.0-mm x 30-cm, packing L1

Flow rate: 2 mL/min

Injection volume: 10 µL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of aspirin (C₉H₈O₄) in the portion of Capsules taken:

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

r_u = peak response of aspirin from the Sample solution

r_s = peak response of aspirin from the Standard solution

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

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

Acceptance criteria: 93.0%-107.0%

PERFORMANCE TESTS

DISSOLUTION (711), Procedure. Apparatus 1 and Apparatus 2. Delayed-Release Dosage Forms. Method A Procedure

Apparatus 1: 100 rpm

Time: 90 min, for Buffer stage; 2 h, for Acid stage

Diluent: 0.1 N hydrochloric acid and 0.20 M tribasic sodium phosphate (3:1). Adjust, if necessary, with 2 N hydrochloric acid or 2 N sodium hydroxide to a pH of 6.8 ± 0.05.

Standard solution: A known concentration of USP Aspirin RS in a suitable medium

Sample solution: Pass a portion of the solution under test through a suitable filter, and dilute with 0.1 N hydrochloric acid (for analyzing in the Acid stage) and with Diluent (for analyzing in the Buffer stage), if necessary.

Instrumental conditions

Mode: UV

Analytical wavelengths

Acid stage: 280 nm

Buffer stage: 265 nm

Analysis

Samples: Standard solution and Sample solution

Determine the percentage of the labeled amount of aspirin (C₉H₈O₄) dissolved from UV absorbances at the isosbestic point of aspirin and salicylic acid (about 280 nm in the Acid stage, and about 265 nm in the Buffer stage).

Tolerances: The percentages of the labeled amount of aspirin (C₉H₈O₄) dissolved conform to Dissolution (711), Acceptance Table 3 (Acid stage) and Acceptance Table 4 (Buffer stage).

UNIFORMITY OF DOSAGE UNITS (905): Meet the requirements

4 IMPURITIES

LIMIT OF FREE SALICYLIC ACID

Mobile phase, Diluent, and Chromatographic system: Proceed as directed in the Assay.

System suitability solution: 0.015 mg/mL of USP Salicylic Acid RS and 0.5 mg/mL of USP Aspirin RS in Diluent

Standard solution: 0.015 mg/mL of USP Salicylic Acid RS in Diluent

Sample solution: Use the Sample stock solution prepared as directed in the Assay.

System suitability

Samples: System suitability solution and Standard solution

[NOTE-The relative retention times for salicylic acid and aspirin are about 0.7 and 1.0, respectively.]

Suitability requirements

Resolution: NLT 2.0 between salicylic acid and aspirin, System suitability solution

Relative standard deviation: NMT 4.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of salicylic acid (C₇H₆O₃) in the portion of Capsules taken:

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

r_u =  peak response of salicylic acid from the Sample solution

r_s = peak response of salicylic acid from the Standard solution

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

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

Acceptance criteria: NMT 3.0%

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.

Labeling: The label indicates that the Capsules or the contents thereof are enteric-coated.

USP Reference Standards 〈11〉

USP Aspirin RS

USP Salicylic Acid RS