Carisoprodol

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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C₁₂H₂₄N₂O₄ 260.33

(±)-2-Methyl-2-propyl-1,3-propanediol carbamate isopropylcarbamate CAS RN®: 78-44-4; UNII: 21925K482H.

1 DEFINITION

Carisoprodol contains NLT 98.0% and NMT 102.0% of C₁₂H₂₄N₂O₄, calculated on the dried basis.

2 IDENTIFICATION

Change to read:

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

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

3 ASSAY

3.1 Procedure

Diluent: Acetonitrile and water (50:50)

Solution A: Acetonitrile and water (25:75)

Solution B: Acetonitrile

Mobile phase: See Table 1.

Table 1

System suitability solution: 0.125 mg/mL each of USP Carisoprodol Related Compound A RS, USP Meprobamate RS, and USP Carisoprodol RS in Diluent

Standard solution: 2.5 mg/mL of USP Carisoprodol RS in Diluent

Sample solution: 2.5 mg/mL of Carisoprodol in Diluent

3.2 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 200 nm

Column: 4.6-mm × 15-cm; 4-μm packing L1

Column temperature: 30°

Flow rate: 1.5 mL/min

Injection size: 25 μL

3.3 System suitability

Samples: System suitability solution and Standard solution

[Note—See Table 2 for the relative retention times.]

3.4 Suitability requirements

Resolution: NLT 1.5 between carisoprodol related compound A and meprobamate, System suitability solution

Tailing factor: NMT 2.5 for the carisoprodol peak, Standard solution

Relative standard deviation: NMT 2.0% for the carisoprodol peak, Standard solution

3.5 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of carisoprodol (C₁₂H₂₄N₂O₄) in the portion of the sample taken:

Result = (r_U/r_S) x (C_S/C_U) × 100

r_U = peak response of carisoprodol from the Sample solution

r_S = peak response of carisoprodol from the Standard solution

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

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

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

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.1%

Change to read:

Organic Impurities

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

Standard solution: 10 μg/mL of USP Carisoprodol RS in Diluent

Sample solution: 50 mg/mL of Carisoprodol in Diluent. [Note—Sonication may be used to aid dissolution.]

System suitability

Samples: System suitability solution and Standard solution

[Note—See Table 2 for the relative retention times.]

Suitability requirements

Resolution: NLT 1.5 between carisoprodol related compound A and meprobamate, System suitability solution

Tailing factor: NMT 2.5 for the carisoprodol peak, Standard solution

Relative standard deviation: NMT 5.0% for the carisoprodol peak, 3 replicate injections of Standard solution

Analysis

Samples: Standard solution and Sample solution

Identify the specifed impurities using the relative retention times given in Table 2.

Calculate the percentage of each impurity in the portion of Carisoprodol taken:

Result = (r_U/r_S) x (C_S/C_U) × (1/F) × 100

r_U = peak response of the impurity from the Sample solution

r_S = peak response of carisoprodol from the Standard solution

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

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

F = relative response factor (see Table 2)

Acceptance criteria: See Table 2.

Table 2

^a 2-Hydroxymethyl-2-methylpentyl carbamate.

^b N-Isopropyl-2-hydroxymethyl-2-methylpentyl carbamate.

5 SPECIFIC TESTS

Loss on Drying 〈731〉: Dry a sample in vacuum at 60° for 3 h: it loses NMT 0.5% of its weight.

6 ADDITIONAL REQUIREMENTS

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

USP Reference Standards 〈11〉

USP Carisoprodol RS

USP Carisoprodol Related Compound A RS

2-Hydroxymethyl-2-methylpentyl carbamate.

C₈H₁₇NO₃ 175.23

USP Meprobamate RS