Pirfenidone Tablets

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

Pirfenidone Tablets contain NLT 95.0% and NMT 105.0% of the labeled amount of pirfenidone (C₁₂H₁₁NO).

2 IDENTIFICATION

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

B. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197A or 197K

Sample: Portion of finely powdered Tablets (NLT 5)

Acceptance criteria: Meet the requirements

3 ASSAY

Procedure

Solution A: 0.1% (v/v) phosphoric acid solution in water prepared as follows. Add 1.0 mL of phosphoric acid to 1 L of water.

Solution B: Acetonitrile

Mobile phase: See Table 1.

Table 1

Diluent: Isopropyl alcohol and water (30:70)

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

Sample stock solution: Nominally 13 mg/mL of pirfenidone in Diluent prepared as follows. Transfer a suitable quantity of Tablets (NLT 5 for 267 mg Tablets or NLT 4 for 801 mg Tablets) to a suitable volumetric flask. Add Diluent to 90% of the final volume and stir for at least 30 min to completely disperse. Dilute with Diluent to volume. Allow to stand for at least 15 min.

Sample solution: Nominally 1.1 mg/mL of pirfenidone from the Sample stock solution in Diluent. Pass a portion of the solution through a suitable filter of 0.20-μm pore size and discard the first 3 mL of fuiltrate.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 220 nm

Column: 4.6-mm × 10-cm; 2.7-μm packing L7

Column temperature: 60°

Flow rate: 2.5 mL/min

Injection volume: 1 μL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 1.5

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of pirfenidone (C₁₂H₁₁NO) in the portion of Tablets taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of pirfenidone from the Sample solution

r_S = peak response of pirfenidone from the Standard solution

C_S = concentration of USP Pirfenidone RS in the Standard solution (mg/mL)

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

Acceptance criteria: 95.0%–105.0%

4 PERFORMANCE TESTS

Dissolution 〈711〉

Medium: Water; 1000 mL

Apparatus 2: 50 rpm

Time: 30 min

Standard solution: (L/1000) mg/mL of USP Pirfenidone RS in Medium, where L is the label claim in mg/Tablet

Sample solution: Pass a portion of the solution under test through a suitable filter of 1.0-μm pore size.

Instrumental conditions

(See Ultraviolet-Visible Spectroscopy 〈857〉.)

Mode: UV

Analytical wavelength: 312 nm

Path length: 0.05 cm

Blank: Medium

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of pirfenidone (C H NO) dissolved:

Result = (A_U/A_S) × C_S × V × (1/L) × 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

C_S = concentration of USP Pirfenidone RS in the Standard solution (mg/mL)

V = volume of Medium, 1000 mL

L = label claim (mg/Tablet)

Tolerances: NLT 80% (Q) of the labeled amount of pirfenidone (C H NO) is dissolved

Uniformity of Dosage Units 〈905〉: Meet the requirements

5 IMPURITIES

Organic Impurities

Solution A, Solution B, Mobile phase, Diluent, Sample stock solution, Sample solution, and Chromatographic system: Proceed as directed in the Assay.

Standard solution: 1.5 μg/mL of USP Pirfenidone RS in Diluent

Sensitivity solution: 0.5 μg/mL of USP Pirfenidone RS from the Standard solution in Diluent

System suitability

Samples: Standard solution and Sensitivity solution

Suitability requirements

Relative standard deviation: NMT 5%, Standard solution

Signal-to-noise ratio: NLT 10, Sensitivity solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of any degradation product in the portion of Tablets taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of any degradation product from the Sample solution

r_S = peak response of pirfenidone from the Standard solution

C_S = concentration of USP Pirfenidone RS in the Standard solution (mg/mL)

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

Acceptance criteria: The reporting threshold is 0.05%.

Any unspecified degradation product: NMT 0.10%

Total degradation products: NMT 0.30%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers. Store at controlled room temperature.

USP Reference Standards 〈11〉

USP Pirfenidone RS