Tetracaine

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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C₁₅H₂₄N₂O₂ 264.36

Benzoic acid, 4-(butylamino)-, 2-(dimethylamino)ethyl ester;

2-(Dimethylamino)ethyl p-(butylamino)benzoate CAS RN®: 94-24-6; UNII: 0619F35CGV.

1 DEFINITION

Tetracaine contains NLT 98.0% and NMT 102.0% of tetracaine (C₁₅H₂₄N₂O₂ ), 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 of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

Procedure

Prepare the standard solutions and sample solutions immediately before use or store them at a temperature of 2°–8°, and protect from light.

Solution A: 1.36 g/L of monobasic potassium phosphate in water is prepared as follows. Dissolve 1.36 g of monobasic potassium phosphate in about 600 mL of water, and add 0.5 mL of phosphoric acid. Dilute with water to 1 L.

Solution B: Acetonitrile

Solution C: 1.0 mL/L of hydrochloric acid

Mobile phase: See Table 1.

Table 1

Diluent: Acetonitrile and Solution C (20:80)

Standard stock solution: 0.46 mg/mL of USP Tetracaine Hydrochloride RS in Diluent. Sonicate for 5 min.

Standard solution: 0.046 mg/mL of USP Tetracaine Hydrochloride RS from Standard stock solution in Diluent

Sample stock solution: 0.4 mg/mL of Tetracaine in Diluent. Sonicate for 5 min.

Sample solution: 0.04 mg/mL of Tetracaine from Sample stock solution in Diluent

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 300 nm

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

Temperatures

Column: 30°

Autosampler: 4°

Flow rate: 1.5 mL/min

Injection volume: 10 μL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 1.5

Relative standard deviation: NMT 0.73%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of tetracaine (C₁₅H₂₄N₂O₂ ) in the portion of Tetracaine taken:

Result = (r_U /r_S ) × (C_S /C_U ) × (M_r1 /M_r2 ) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

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

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

M_r1 = molecular weight of tetracaine, 264.36

M_r2 = molecular weight of tetracaine hydrochloride, 300.82

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

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.1%

Organic Impurities

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

Standard solution: 4.6 μg/mL of USP Tetracaine Hydrochloride RS and 4 μg/mL each of USP Tetracaine Related Compound B RS, USP

Tetracaine Related Compound C RS, and USP Aminobenzoic Acid RS in Diluent

Sample solution: 1 mg/mL of Tetracaine in Diluent

System suitability

Sample: Standard solution

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

Suitability requirements

Resolution: NLT 5.0 between tetracaine and tetracaine related compound B

Relative standard deviation: NMT 5.0% for tetracaine

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of aminobenzoic acid, tetracaine related compound B, and tetracaine related compound C in the portion of

Tetracaine taken:

Result = (r_U /r_S ) × (C_S /C_U ) × 100

r_U = peak response of corresponding tetracaine related compound from the Sample solution

r_S = peak response of corresponding tetracaine related compound from the Standard solution

C_S = concentration of corresponding tetracaine related compound in the Standard solution (mg/mL)

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

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

Result = (r_U /r_S ) × (C_S /C_U ) × (M_r1 /M_r2 ) × 100

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

r_S = peak response from the Standard solution

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

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

M_r1 = molecular weight of tetracaine, 264.36

M_r2 = molecular weight of tetracaine hydrochloride, 300.82

Acceptance criteria: See Table 2. Disregard any impurity peaks less than 0.05%.

Table 2

^a 4-Aminobenzoic acid.

5 SPECIFIC TESTS

Loss on Drying 〈731〉

Analysis: Dry under vacuum over phosphorus pentoxide for 18 h.

Acceptance criteria: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers.

USP Reference Standards 〈11〉

USP Aminobenzoic Acid RS

USP Tetracaine RS

USP Tetracaine Related Compound B RS

4-(Butylamino)benzoic acid.

C₁₁H₁₅NO₂ 193.24

USP Tetracaine Related Compound C RS

Methyl 4-(butylamino)benzoate.

C₁₂H₁₇NO₂ 207.35