Ampicillin Sodium

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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Ampicillin Sodium

C₁₆H₁₈N₃NaO₄S 371.39

4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid, [6-(aminophenylacetyl)amino]-3,3-dimethyl-7-oxo-, monosodium salt, [2S-[2α,5α,6β(S*)]]-;

Monosodium D-(−)-6-(2-amino-2-phenylacetamido)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate

CAS RN®: 69-52-3;

UNII: JFN36L5S8K.

1 DEFINITION

Ampicillin Sodium has a potency equivalent to NLT 845 µg and NMT 988 µg of ampicillin (C₁₆H₁₉N₃O₄S) per mg, calculated on the anhydrous basis.

2 IDENTIFICATION

Change to read:

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

B. Identification Tests—General, Sodium 〈191〉

ASSAY

Procedure

Diluent: Water, 1 M monobasic potassium phosphate, and 1 N acetic acid (989:10:1)

Mobile phase: Acetonitrile, water, 1 M monobasic potassium phosphate, and 1 N acetic acid (80:909:10:1)

Standard solution: 1 mg/mL of USP Ampicillin RS in Diluent using shaking and sonication, if necessary, to dissolve. Use this solution promptly after preparation.

System suitability solution: 0.12 mg/mL of caffeine in Standard solution

Sample solution: [Note—Ampicillin Sodium is hygroscopic. Minimize exposure to the atmosphere, and weigh promptly.] Equivalent to 1 mg/mL of anhydrous ampicillin in Diluent. [Note—Use this solution promptly after preparation.]

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column

Pre-column: 4-mm × 5-cm; 5- to 10-µm packing L1

Analytical column: 4-mm × 30-cm; 5- to 10-µm packing L1

Flow rate: 2 mL/min

Injection size: 20 µL

System suitability

Samples: Standard solution and System suitability solution

[Note—The relative retention times for ampicillin and caffeine are 0.5 and 1.0, respectively, System suitability solution.]

Suitability requirements

Resolution: NLT 2.0 between the caffeine and the ampicillin peaks, System suitability solution

Tailing factor: NMT 1.4, Standard solution

Capacity factor: NMT 2.5, Standard solution

Relative standard deviation: NMT 2.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the quantity, in µg, of C₁₆H₁₉N₃O₄S in each mg of Ampicillin Sodium taken:

Result = (rᵤ/rₛ) × (Cₛ/Cₓ) × P

rᵤ = peak response from the Sample solution

rₛ = peak response from the Standard solution

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

Cₓ = nominal concentration of Ampicillin Sodium in the Sample solution (mg/mL)

P = potency of USP Ampicillin RS (µg/mg)

Acceptance criteria: 845–988 µg/mg on the anhydrous basis

3 IMPURITIES

Organic Impurities

Procedure 1: Limit of Methylene Chloride

Internal standard solution: 2.1 mg/mL of dioxane in dimethyl sulfoxide

Standard solution: 0.33 mg/mL of methylene chloride in Internal standard solution

Sample solution: 166.7 mg/mL of Ampicillin Sodium in Internal standard solution

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 1.8-m × 4-mm glass column packed with a 10% phase G39 on unsilanized support S1A

Temperature

Column: 65°

Injector: 100°

Detector block: 260°

Carrier gas: Nitrogen

Flow rate: 60 mL/min

Injection size: 1 µL

System suitability

Sample: Standard solution

[Note—The relative retention times for methylene chloride and dioxane are 0.5 and 1.0, respectively.]

Suitability requirements

Resolution: NLT 4 between methylene chloride and dioxane

Relative standard deviation: NMT 5%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of methylene chloride in the portion of Ampicillin Sodium taken:

Result = (Rᵤ/Rₛ) × (Cₛ/Cₓ) × 100

Rᵤ = peak response ratio of methylene chloride to dioxane from the Sample solution

Rₛ = peak response ratio of methylene chloride to dioxane from the Standard solution

Cₛ = concentration of methylene chloride in the Standard solution (mg/mL)

Cₓ = nominal concentration of Ampicillin Sodium in the Sample solution (mg/mL)

Acceptance criteria: NMT 0.2%

Procedure 2: Dimethylaniline 〈223〉: Meets the requirement

4 SPECIFIC TESTS

Crystallinity 〈695〉: Meets the requirements. [Note—Ampicillin Sodium in the freeze-dried form is exempt from this requirement.]

pH 〈791〉: 8.0–10.0

Sample solution: 10.0 mg/mL of ampicillin

Water Determination, Method I 〈921〉: NMT 2.0%

Sterility Tests 〈71〉: Where the label states that Ampicillin Sodium is sterile, it meets the requirements.

Bacterial Endotoxins Test 〈85〉: Where the label states that Ampicillin Sodium is sterile or the label states that Ampicillin Sodium must be subjected to further processing during the processing of injectable dosage forms, it contains NMT 0.15 USP Endotoxin Unit/mg of ampicillin.

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.

Labeling: Where it is intended for use in preparing injectable dosage forms, the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms.

USP Reference Standards 〈11〉

USP Ampicillin RS

USP Ampicillin Sodium RS