Prilocaine and Epinephrine Injection

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

Prilocaine and Epinephrine Injection is a sterile solution prepared from Prilocaine Hydrochloride and Epinephrine with the aid of Hydrochloric Acid in Water for Injection, or a sterile solution of Prilocaine Hydrochloride and Epinephrine Bitartrate in Water for Injection. The content of epinephrine does not exceed 0.002% (1 in 50,000). Prilocaine and Epinephrine Injection contains the equivalent of NLT 95.0% and NMT 105.0% of the labeled amount of prilocaine hydrochloride (C₁₃H₂₀N₂O·HCl) and the equivalent of NLT 90.0% and NMT 115.0% of the labeled amount of epinephrine (C₉H₁₃NO₃).

2 IDENTIFICATION

A.

Sample: A volume of Injection equivalent to 300 mg of prilocaine hydrochloride

Analysis: Dilute the Sample with 5 mL of water, and add 4 mL of 6 N ammonium hydroxide. Extract with 50 mL of chloroform, and filter the extract. Evaporate the filtrate on a steam bath with the aid of a current of air. Dissolve 100 mg of the prilocaine so obtained in 1 mL of alcohol, add 10 drops of cobaltous chloride TS, and shake for 2 min.

Acceptance criteria: A bright green color develops, and a precipitate is formed.

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

C. The retention time of the major peak for epinephrine of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay for Epinephrine.

3 ASSAY

Prilocaine Hydrochloride

Solution A: 50 mL of glacial acetic acid in 930 mL of water. Adjust with 1 N sodium hydroxide to a pH of 3.40.

Mobile phase: Acetonitrile and Solution A (1:4). Adjust the ratio of the mobile phase components to obtain a retention time of 4–6 min for the prilocaine peak. Pass through a membrane filter of 1-µm or finer pore size, and degas.

Standard solution: 4 mg/mL of USP Prilocaine Hydrochloride RS in Mobile phase

System suitability stock solution: 900 µg/mL of procainamide hydrochloride in Mobile phase

System suitability solution: System suitability stock solution and Standard solution (1:10)

Sample solution: Nominally 4 mg/mL of prilocaine hydrochloride from Injection, in Mobile phase

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 3.9-mm × 30-cm; packing L1

Column temperature: 20°–25°, maintained at ±1.0° of the selected temperature

Flow rate: 1.5 mL/min

Injection volume: 10 µL

System suitability

Samples: Standard solution and System suitability solution

Suitability requirements

Resolution: NLT 2.0 between prilocaine and procainamide, System suitability solution

Relative standard deviation: NMT 1.5%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of prilocaine hydrochloride (C₁₃H₂₀N₂O·HCl) in the volume of Injection taken:

Result = (rᵤ / rₛ) × (Cₛ / Cᵤ) × 100

rᵤ = peak area of prilocaine hydrochloride from the Sample solution

rₛ = peak area of prilocaine hydrochloride from the Standard solution

Cₛ = concentration of USP Prilocaine Hydrochloride RS in the Standard solution (mg/mL)

Cᵤ = nominal concentration of prilocaine hydrochloride in the Sample solution (mg/mL)

Acceptance criteria: 95.0%–105.0%

Epinephrine

Solution A: Mix 50 mL of glacial acetic acid and 930 mL of water, and adjust with 1 N sodium hydroxide to a pH of 3.40. Dissolve 1.1 g of sodium 1-heptanesulfonate in this solution, and add 1.0 mL of 0.1 M disodium ethylenediaminetetraacetate.

Mobile phase: Methanol and Solution A (1:9). Pass through a membrane filter of 1-µm or finer pore size, and degas.

Standard solution: 1.8 µg/mL of USP Epinephrine Bitartrate RS in Mobile phase

Sample solution: Nominally 1 µg/mL of epinephrine from Injection in Mobile phase

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: An electrochemical detector held at a potential of +650 mV, and a controller capable of regulating the background current

Column: 3.9-mm × 30-cm; packing L1

Column temperature: 20°–25°, maintained at ±1.0° of the selected temperature

Flow rate: 1 mL/min

Injection volume: 20 µL

System suitability

Sample: Standard solution

Suitability requirements

Relative standard deviation: NMT 1.5%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of epinephrine (C₉H₁₃NO₃) in the volume of Injection taken:

Result = (rᵤ / rₛ) × (Cₛ / Cᵤ) × (M₁ / M₂) × 100

rᵤ = peak response of epinephrine from the Sample solution

rₛ = peak response of epinephrine from the Standard solution

Cₛ = concentration of USP Epinephrine Bitartrate RS in the Standard solution (µg/mL)

Cᵤ = nominal concentration of epinephrine in the Sample solution (µg/mL)

M₁ = molecular weight of epinephrine, 183.20

M₂ = molecular weight of epinephrine bitartrate, 333.29

Acceptance criteria: 90.0%–115.0%

4 SPECIFIC TESTS

Color and Clarity

Standard solution: Transfer 2.0 mL of 0.100 N iodine VS to a 500-mL volumetric flask, and dilute with water to volume.

Sample solution: A portion of the Injection

Analysis

Samples: Standard solution and Sample solution

Visually examine the Sample solution in a suitable clear glass test tube against a white background: it is not pinkish, and it contains no precipitate. If any yellow color is observed in the Sample solution, concomitantly determine the absorbances of the Sample solution and the Standard solution in 1-cm cells with a suitable spectrophotometer set at 460 nm.

Acceptance criteria: The absorbance of the Sample solution does not exceed that of the Standard solution.

Bacterial Endotoxins Test 〈85〉: It contains NMT 0.9 USP Endotoxin Unit/mg of prilocaine hydrochloride.

pH 〈791〉: 3.3–5.5

Other Requirements: It meets the requirements in Injections and Implanted Drug Products 〈1〉.

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in single-dose or multiple-dose light-resistant containers, preferably of Type I glass.

Labeling: The label indicates that the Injection is not to be used if its color is pinkish or darker than slightly yellow or if it contains a precipitate.

USP Reference Standards 〈11〉

USP Epinephrine Bitartrate RS

USP Prilocaine Hydrochloride RS