Mafenide Acetate for Topical Solution

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

Mafenide Acetate for Topical Solution contains NLT 98.0% and NMT 102.0% of mafenide acetate (C₇H₁₀N₂O₂S · C₂H₄O₂), calculated on the anhydrous basis.

2 IDENTIFICATION

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

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

3 ASSAY

Procedure

Solution A: Dissolve 6.8 g of monobasic potassium phosphate and 1.0 g of sodium 1-hexanesulfonate in 800 mL of water. Adjust with phosphoric acid to a pH of 2.5, and dilute to 1000 mL.

Mobile phase: Acetonitrile and Solution A (1:9)

Standard solution: 1 mg/mL of USP Mafenide Acetate RS in Mobile phase. Sonicate to dissolve if necessary.

Sample solution: Nominally 1 mg/mL of mafenide acetate prepared as follows. Constitute the Topical Solution as directed in the labeling.

Transfer a volume of the constituted Topical Solution, equivalent to 25 mg of mafenide acetate, to a 25-mL volumetric flask. Using sonication, dissolve in 12 mL of Mobile phase. Dilute with Mobile phase to volume.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 267 nm

Column: 4.6-mm × 15-cm; 5-μm packing L1

Flow rate: 1 mL/min

Injection volume: 20 μL

System suitability

Sample: Standard solution

Suitability requirements

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of mafenide acetate (C₇H₁₀N₂O₂S · C₂H₄O₂) in the portion of the constituted Topical

Solution 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 USP Mafenide Acetate RS in the Standard solution (mg/mL)

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

Acceptance criteria: 98.0%–102.0% on the anhydrous basis

4 OTHER COMPONENTS

Content of Acetic Acid

Internal standard solution: 0.5% (v/v) of propionic acid in water

Standard stock solution: Transfer 50 mL of water to a 100-mL volumetric flask, insert a stopper, and weigh. Add 0.5 mL of glacial acetic acid to the flask, insert the stopper, weigh, and calculate, by difference, the amount of acetic acid added. Dilute with water to volume.

Standard solution: 530 μg/mL of acetic acid prepared as follows. Add 10.0 mL of Standard stock solution and 10.0 mL of Internal standard solution to a 100-mL volumetric flask containing 200 mg of oxalic acid. Dilute with water to volume.

Sample solution: Nominally 2 mg/mL of mafenide acetate prepared as follows. Constitute the Topical Solution as directed in the labeling.

Transfer a volume of the constituted Topical Solution, equivalent to 200 mg of mafenide acetate, to a 100-mL volumetric flask containing 200 mg of oxalic acid. Pipet 10.0 mL of Internal standard solution into the flask, and dilute with water to volume.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.25-mm × 60-m fused-silica capillary column coated with a 0.5-μm layer of acid-deactivated phase G35

Temperatures

Injection: 250°

Detector: 250°

Column: See Table 1.

Table 1

Carrier gas: Helium

Flow rate: 40 cm/s

Injection volume: 1 μL

System suitability

Sample: Standard solution

Suitability requirements

Resolution: NLT 3.0 between acetic acid and propionic acid

Relative standard deviation: NMT 6.0% for peak response ratios

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of acetic acid in the portion of the constituted Topical Solution taken:

Result = (R_U/R_S) × (C_S/C_U) × 100

R_U = peak response ratio of acetic acid to propionic acid from the Sample solution

R_S = peak response ratio of acetic acid to propionic acid from the Standard solution

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

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

Acceptance criteria: 22.0%–26.8%

5 IMPURITIES

Change to read:

Organic Impurities

Solution A: Dissolve 6.8 g of monobasic potassium phosphate and 1.0 g of sodium 1-hexanesulfonate in 800 mL of water. Adjust with phosphoric acid to a pH of 2.5, and dilute to 1000 mL.

Mobile phase: Acetonitrile and Solution A (1:9)

Standard stock solution: 25 μg/mL of USP Mafenide Related Compound A RS in Mobile phase

[Note—USP Mafenide Related Compound A RS is 4-formylbenzenesulfonamide.]

System suitability solution: 1.0 mg/mL of USP Mafenide Acetate RS and 10 μg/mL of USP Mafenide Related Compound A RS from Standard stock solution in Mobile phase. Initially dissolve the USP Mafenide Acetate RS using 20% of the final volume by sonication in 2 mL of Mobile phase, add the appropriate volume of USP Mafenide Related Compound A RS, and dilute to final volume.

Standard solution A: 5 μg/mL of USP Mafenide Related Compound A RS from Standard stock solution in Mobile phase

Standard solution B: 1 μg/mL of USP Mafenide Related Compound A RS from Standard solution A in Mobile phase

Sample solution: Proceed as directed in the Assay.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 267 nm

Column: 4.6-mm × 15-cm; 5-μm packing L1

Flow rate: 1 mL/min

Injection volume: 20 μL

Run time: 3 times the retention time of mafenide

System suitability

Samples: System suitability solution and (ERR 1-Jan-2023) Standard solution A (ERR 1-Jan-2023)

Suitability requirements

Resolution: NLT 3.0 between mafenide acetate and mafenide related compound A, System suitability solution

Tailing factor: NMT 2.0, System suitability solution

Relative standard deviation: NMT 2.0%, Standard solution A

Analysis

Samples: Mobile phase, Standard solution A, Standard solution B, (ERR 1-Jan-2023) and Sample solution

Chromatograph Standard solution B (ERR 1-Jan-2023) and adjust the integration parameters so that the response is 5%–15% of full-scale deffiection. Disregard the peaks corresponding to those obtained from the Mobile phase.

Calculate the percentage of each impurity in the portion of the constituted Topical Solution taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response for each impurity from the Sample solution

r_S = peak response of mafenide related compound A from Standard solution A

C_S = concentration of USP Mafenide Related Compound A RS in Standard solution A (μg/mL)

C_U = nominal concentration of mafenide acetate in the Sample solution (μg/mL)

Acceptance criteria

Individual impurity: NMT 0.5%

Total impurities: NMT 1.0%

6 SPECIFIC TESTS

pH 〈791〉

Sample solution: Nominally 100 mg/mL

Acceptance criteria: 6.4–6.8

Water Determination, Method I〈921〉: NMT 1.0%

7 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers, at controlled room temperature. For prepared solutions, use within 48 h of preparation.

USP Reference Standards 〈11〉

USP Mafenide Acetate RS

USP Mafenide Related Compound A RS

4-Formylbenzenesulfonamide.

C₇H₇NO₃S 185.20