Carmustine

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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C₅H₉Cl₂N₃O₂ 214.05

Urea, N,N'-bis(2-chloroethyl)-N-nitroso-;

1,3-Bis(2-chloroethyl)-1-nitrosourea CAS RN®: 154-93-8; UNII: U68WG3173Y.

1 DEFINITION

Carmustine contains NLT 98.0% and NMT 102.0% of C₅H₉Cl₂N₃O₂, calculated on the anhydrous and solvent-free basis.

[Caution—Use appropriate surgical gloves, arm covers, and a dust mask. Perform all work under a fume hood approved for testing cytotoxic agents when possible.]

2 IDENTIFICATION

Change to read:

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197F (CN 1-May-2020)

Sample: Melt a small portion of the sample in a suitable container in a controlled water bath or oven, and set the temperature between 33° and 40°.

Standard: A similar preparation of USP Carmustine RS

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

[Note—Prepare solutions in low-actinic glassware, and keep them refrigerated until use.]

Mobile phase: Acetonitrile and water (3:7)

Standard solution: 1.5 mg/mL of USP Carmustine RS in acetonitrile

Sample solution: 1.5 mg/mL of Carmustine in acetonitrile

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 200 nm

Refrigerated autosampler temperature: 4°–5°

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

Flow rate: 1.5 mL/min

Injection size: 10 μL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 1.9

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of C₅H₉Cl₂N₃O₂ in the portion of Carmustine 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 Carmustine RS in the Standard solution (mg/mL)

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

Acceptance criteria: 98.0%–102.0% on the anhydrous and solvent-free basis

4 IMPURITIES

Organic Impurities

Procedure 1: Limit of Ether-Insoluble Substances

[Note—Perform in a well-ventilated fume hood.]

Analysis: Transfer 1.0 g of sample to a suitable container containing 10 mL of anhydrous ether, stir for 5 min, and immediately filter through a tared glass-filtering crucible of medium pore size. Wash the container with an additional 10 mL of ether, and filter through the same glass-filtering crucible. Dry the crucible at 105° for 1 h. Cool in a desiccator and weigh.

Acceptance criteria: The weight of the residue does not exceed 0.1%.

Procedure 2: Limit of Carmustine Related Compound A

[Note—Prepare solutions in low-actinic glassware, and keep them refrigerated until use.]

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

Carmustine standard solution: Use the Standard solution, prepared as directed in the Assay.

Standard stock solution: 0.75 mg/mL of USP Carmustine Related Compound A RS in acetonitrile

Standard solution: 0.0075 mg/mL of USP Carmustine Related Compound A RS in acetonitrile, from the Standard stock solution

System suitability solution 1: 0.75 μg/mL of USP Carmustine Related Compound A RS in acetonitrile, from the Standard solution

System suitability solution 2: Transfer 5.0 mL of Carmustine standard solution and 10.0 mL of Standard stock solution into a 100-mL volumetric flask, and dilute with acetonitrile to volume. Transfer 5.0 mL of this solution into a 50-mL volumetric flask, and dilute with acetonitrile to volume.

System suitability

Samples: Carmustine standard solution, System suitability solution 1, and System suitability solution 2

[Note—The relative retention times for carmustine related compound A and carmustine are 0.3 and 1.0, respectively.]

Suitability requirements

Resolution: NLT 10 between carmustine related compound A and carmustine, System suitability solution 2

Tailing factor: NMT 1.9, Carmustine standard solution

Relative standard deviation: NMT 5%, System suitability solution 1

Analysis

[Note—Run the Sample solution at least 1.5 times the retention time of carmustine.]

Samples: Standard solution and Sample solution

Calculate the percentage of carmustine related compound A in the portion of Carmustine taken:

Result = (r_U/r_S) x (C_S/C_U) × 100

r_U = peak response of carmustine related compound A from the Sample solution

r_S = peak response of carmustine related compound A from the Standard solution

C_S = concentration of carmustine related compound A in the Standard solution (mg/mL)

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

Calculate the percentage of each unspecified impurity in the portion of Carmustine taken:

Result = (r_U/r_T) × 100

r_U = peak response of any unspecified impurity from the Sample solution

r_T = sum of all peak responses from the Sample solution

Acceptance criteria

Carmustine related compound A: NMT 0.5%

Any unspecified impurity: NMT 0.1%

Procedure 3: Limit of 2-Chloroethylamine

[Note—Prepare solutions in low-actinic glassware, and keep them refrigerated until use.]

Standard solution 1 (0.2%): 1.2 mg/mL of 2-chloroethylamine monohydrochloride in methanol. [Note—1.2 mg/mL of 2-chloroethylamine monohydrochloride is equivalent to 0.8 mg/mL of 2-chloroethylamine.]

Standard solution 2 (0.1%): 0.4 mg/mL of USP Carmustine RS in methanol

Sample solution: 0.4 g/mL of Carmustine in methanol

Chromatographic system

(See Chromatography 〈621〉, Thin-Layer Chromatography.)

Mode: TLC

Adsorbent: 0.25-mm layer of chromatographic plate (20-cm × 20-cm) coated with silica gel 60

Application volume: 1 μL

Developing solvent system 1: Ethyl acetate

Developing solvent system 2: Ethyl acetate and methanol (7:3)

Spray reagent 1: Diethylamine

Spray reagent 2: 0.1 N silver nitrate solution

Analysis

Samples: Standard solution 1 (0.2%), Standard solution 2 (0.1%), and Sample solution

Develop with Developing solvent system 1 for 27 min, followed by air drying for 5 min. Develop again in Developing solvent system 2 for 8 min, followed by air drying for 10 min. Spray the plate with Spray reagent 1, and heat the plate for 20 min in an oven at 100°. Allow the plates to cool to room temperature, and spray the plate with Spray reagent 2. Allow the plate to be exposed to UV light at 365 nm for 15 min. Examine the plate under UV light.

Acceptance criteria

2-Chloroethylamine: The spot for 2-chloroethylamine from the Sample solution is not more intense than the principal spot from Standard solution 1 (0.2%).

Any unspecified impurity: Any spot if present in the chromatogram from the Sample solution, except the principal spot of carmustine and the spot of 2-chloroethylamine, is not more intense than the principal spot from Standard solution 2 (0.1%).

Procedure 4: Limit of 2-Chloroethanol

Standard solution: 0.02 mg/mL of 2-chloroethanol in acetonitrile

System suitability solution: 0.01 mg/mL of 2-chloroethanol in acetonitrile, diluted from the Standard solution

Sample solution: 10 mg/mL of Carmustine in acetonitrile. [Note—Prepare in low-actinic glassware, and keep refrigerated until use.]

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 30-m × 0.53-mm column bonded with a 1-μm

lm of phase G16

Temperature

Injector: 90°

Detector: 260°

Column: See the temperature program table below.

Carrier gas: Helium

Flow rate: 7 mL/min

Injection size: 5 μL

System suitability

Sample: System suitability solution

Suitability requirements

Relative standard deviation: NMT 5%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of 2-chloroethanol in the portion of Carmustine taken:

Result = (r_U/r_S) x (C_S/C_U) × 100

r = peak response of 2-chloroethanol from the Sample solution

r = peak response of 2-chloroethanol from the Standard solution

C = concentration of 2-chloroethanol in the Standard solution (mg/mL)

C = concentration of Carmustine in the Sample solution (mg/mL)

Acceptance criteria

2-Chloroethanol: NMT 0.1%

Procedure 5: Limit of Acetaldehyde

Standard solution: 10 μg/mL of acetaldehyde in acetonitrile

Sample solution: 10 mg/mL of Carmustine in acetonitrile. [Note—Prepare in low-actinic glassware, and keep refrigerated until use.]

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 30-m × 0.53-mm column bonded with a 5-μm

lm of phase G1

Temperature

Injector: 70°

Detector: 260°

Column: See the temperature program table below.

Injector split ratio: 15:1

Carrier gas: Helium

Flow rate: 3 mL/min

Injection size: 5 μL

System suitability

Sample: Standard solution

Suitability requirements

Relative standard deviation: NMT 5%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of acetaldehyde in the portion of Carmustine taken:

Result = (r_U/r_S) x (C_S/C_U) × 100

r = peak response of acetaldehyde from the Sample solution

r = peak response of acetaldehyde from the Standard solution

C = concentration of acetaldehyde in the Standard solution (mg/mL)

C = concentration of Carmustine in the Sample solution (mg/mL)

Acceptance criteria

Acetaldehyde: NMT 0.1%

5 SPECIFIC TESTS

Water Determination, Method I〈921〉: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers at a temperature between 2° and 8°.

USP Reference Standards 〈11〉

USP Carmustine RS

USP Carmustine Related Compound A RS

1,3-Bis(2-chloroethyl) Urea.

C₅H₁₀Cl₂N₂O 185.05