Amoxicillin and Clavulanic Acid Extended-Release Tablets

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

Amoxicillin and Clavulanic Acid Extended-Release Tablets contain NLT 90.0% and NMT 110.0% of the labeled amounts of amoxicillin (C₁₆H₁₉N₃O₅S) and clavulanic acid (C₈H₉NO₅).

2 IDENTIFICATION

A. The retention times of the major peaks of the Sample solution correspond to those of the Standard solution, as obtained in the Assay.

3 ASSAY

Procedure

Buffer: 6.9 g/L of monobasic sodium phosphate adjusted with phosphoric acid to a pH of 4.2

Mobile phase: Methanol and Buffer (5:95)

Standard solution: 1 mg/mL of USP Amoxicillin RS and 62.5 µg/mL of USP Clavulanate Lithium RS in water. Store the solution at 4°, and inject within 10 h.

Sample solution: Equivalent to 1 mg/mL of amoxicillin and 62.5 µg/mL of clavulanic acid from finely powdered Tablets (NLT 6) in water. Stir for about 60 min. Store the solution at 4°, and inject within 12 h.

3.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 229 nm

Column: 8-mm × 10-cm; 5-µm packing L1

Flow rate: 2 mL/min

Injection volume: 20 µL

Autosampler temperature: 4°

3.2 System suitability

Sample: Standard solution

Suitability requirements

Resolution: NLT 2.0 between the amoxicillin and clavulanic acid peaks

Tailing factor: NMT 1.8 for the amoxicillin and clavulanic acid peaks

Relative standard deviation: NMT 1.0% for the amoxicillin and clavulanic acid peaks

3.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of amoxicillin (C₁₆H₁₉N₃O₅S) in the portion of Tablets taken:

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

r_U = response of amoxicillin from the Sample solution

r_S = response of amoxicillin from the Standard solution

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

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

P = potency of amoxicillin in USP Amoxicillin RS (µg/mg)

F = conversion factor, 0.001 mg/µg

Calculate the percentage of the labeled amount of clavulanic acid (C₈H₉NO₅) in the portion of Tablets taken:

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

r_U = response of clavulanic acid from the Sample solution

r_S = response of clavulanic acid from the Standard solution

C_S = concentration of USP Clavulanate Lithium RS in the Standard solution (µg/mL)

C_U = nominal concentration of clavulanic acid in the Sample solution (µg/mL)

P = potency of clavulanic acid in USP Clavulanate Lithium RS (mg/mg)

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

Dissolution 〈711〉

4.1 Test 1

Medium: Water; 900 mL

Apparatus 2: 75 rpm

Times

Amoxicillin: 1, 3, and 5 h

Clavulanic acid: 1 h

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

Standard solution: USP Amoxicillin RS and USP Clavulanate Lithium RS in Medium at known concentrations similar to those expected in the Sample solution

Sample solution: Pass a portion of the solution under test through a suitable filter, and dilute with Medium, if necessary.

Analysis

Samples: Standard solution and Sample solution

Calculate the amounts of amoxicillin (C₁₆H₁₉N₃O₅S) and clavulanic acid (C₈H₉NO₅) dissolved.

Tolerances

Amoxicillin: The percentage of the labeled amount of amoxicillin (C₁₆H₁₉N₃O₅S) dissolved at the times specified conforms to Table 1.

Table 1

Clavulanic acid: NLT 80% (Q) of the labeled amount of clavulanic acid (C₈H₉NO₅) is dissolved in 1 h.

4.2 Test 2

Medium: Water; 900 mL

Apparatus 2: 75 rpm

Times

Amoxicillin: 1, 3, and 5 h

Clavulanic acid: 45 min

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

Standard solution: USP Amoxicillin RS and USP Clavulanate Lithium RS in Medium at known concentrations similar to those expected in the Sample solution

Sample solution: Pass a portion of the solution under test through a suitable filter, and dilute with Medium, if necessary.

Analysis

Samples: Standard solution and Sample solution

Calculate the amounts of amoxicillin (C₁₆H₁₉N₃O₅S) and clavulanic acid (C₈H₉NO₅) dissolved.

Tolerances

Amoxicillin: The percentage of the labeled amount of amoxicillin (C₁₆H₁₉N₃O₅S) dissolved at the times specified conforms to Table 2.

Table 2

Clavulanic acid: NLT 85% (Q) of the labeled amount of clavulanic acid (C₈H₉NO₅) is dissolved in 45 min.

Uniformity of Dosage Units 〈905〉: Meet the requirements

5 IMPURITIES

Organic Impurities

Buffer: 13.8 g/L of monobasic sodium phosphate in water adjusted with phosphoric acid to a pH of 4.2

Solution A: Methanol and Buffer (1:199)

Solution B: Methanol and Buffer (10:90)

Mobile phase: See Table 3.

Table 3

[Note—These gradient elution times are established on an HPLC system with a dwell volume of approximately 5 mL. The gradient elution times in Table 3 can be adjusted as necessary to achieve the separation described.]

System suitability solution: 0.4 mg/mL of USP Amoxicillin RS and 30 µg/mL of USP Amoxicillin Related Compound D RS in water. Store the solution at 4°.

Standard solution: 0.4 mg/mL of USP Amoxicillin RS in water. Store the solution at 4°, and inject within 24 h.

Sample solution: 1 mg/mL of amoxicillin and 62.5 µg/mL of clavulanic acid from finely powdered Tablets (NLT 2) in water. Stir for about 60 min. Store the solution at 4°, and use within 24 h.

5.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 230 nm

Column: 4.6-mm × 5-cm; 3-µm packing L1

Flow rate: 1.5 mL/min

Injection volume: 20 µL

Autosampler temperature: 4°

5.2 System suitability

Samples: System suitability solution and Standard solution

Suitability requirements

Resolution: NLT 1.25 between the amoxicillin and amoxicillin related compound D peaks at a relative retention time of 0.83, System suitability solution

Tailing factor: NMT 1.8 for the amoxicillin peak, Standard solution

Relative standard deviation: NMT 1.0% for the amoxicillin peak, Standard solution

5.3 Analysis

Samples: Standard solution and Sample solution

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

Result = (r_U /r_S) × (C_S /C_U ) × P × F₁ × (1/F₂ ) × 100

r_U = response of each impurity from the Sample solution

r_S = response of amoxicillin from the Standard solution

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

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

P = potency of amoxicillin in USP Amoxicillin RS (µg/mg)

F₁ = conversion factor, 0.001 mg/µg

F₂ = relative response factor (see Table 4)

Acceptance criteria: See Table 4. The reporting limit is 0.003%.

Table 4

^aThese are synthetic process impurities, which are controlled in the drug substance. They are listed here for reference only and are not to be reported.

^b (R)-2-Amino-2-(4-hydroxyphenyl)acetic acid.

^c (2S,5R,6R)-6-Amino-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0] heptane-2-carboxylic acid.

^d The chromatographic system resolves two isomers of amoxicillin open ring.

^e (4S)-2-{[(R)-2-Amino-2-(4-hydroxyphenyl)acetamido](carboxy)methyl}-5,5-dimethylthiazolidine-4-carboxylic acid. f (2S,5R,6R)-6-[(S)-2-Amino-2-(4-hydroxyphenyl)acetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid. g(2S,5R,6R)-6-{(R)-2-[(R)-2-Amino-2-(4-hydroxyphenyl)acetamido]-2-(4-hydroxyphenyl)acetamido}-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0]heptane-2-carboxylic acid.

^h The chromatographic system resolves two amoxicillin penilloic derivatives.

ⁱ (4S)-2-{[(R)-2-Amino-2-(4-hydroxyphenyl)acetamido]methyl}-5,5-dimethylthiazolidine-4-carboxylic acid.

^j (4S)-2-[5-(4-Hydroxyphenyl)-3,6-dioxopiperazin-2-yl]-5,5-dimethylthiazolidine-4-carboxylic acid.

^k (4S)-2-{[(R)-2-Amino-2-(4-hydroxyphenyl)acetamido]methoxycarbonylmethyl}-5,5-dimethylthiazolidine-4-carboxylic acid. l (2S,5R,6R)-6-((2R)-2-{2-[(R)-2-Amino-2-(4-hydroxyphenyl)acetamido]-2-[(4S)-4-carboxy-5,5-dimethylthiazolidin-2-yl]acetamido}-2-(4- hydroxyphenyl)acetamido)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid.

6 SPECIFIC TESTS

Microbial Enumeration Tests 〈61〉and Tests for Specified Microorganisms 〈62〉: The total aerobic microbial count does not exceed 103 cfu/g, and the total combined molds and yeasts count does not exceed 102 cfu/g.

7 ADDITIONAL REQUIREMENTS

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

Labeling: When more than one Dissolution test is given, the labeling states the test used only if Test 1 is not used.

USP Reference Standards 〈11〉

USP Amoxicillin RS

USP Amoxicillin Related Compound D RS

(4S)-2-{[(R)-2-Amino-2-(4-hydroxyphenyl)acetamido](carboxy)methyl}-5,5-dimethylthiazolidine-4-carboxylic acid.

C₁₆H₂₁N₃O₆S       383.42

USP Clavulanate Lithium RS