Cefadroxil for Oral Suspension

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

Cefadroxil for Oral Suspension is a dry mixture of Cefadroxil and one or more suitable buffers, colors, diluents, and flavors. It contains the equivalent of NLT 90.0% and NMT 120.0% of the labeled amount of C₁₆H₁₇N₃O₅S.

2 IDENTIFICATION

Thin-Layer Chromatography

Standard solution: 2 mg/mL of USP Cefadroxil RS

Sample solution: Constitute 1 container of Cefadroxil for Oral Suspension as directed in the labeling. Dilute a portion of the resulting suspension with water to a concentration of 2 mg/mL. Pass through a suitable filter.

2.1 Chromatographic system

(See Chromatography 〈621〉, Thin-Layer Chromatography.)

Mode: TLC

Adsorbent: 0.25-mm layer of binder-free silica gel

Application volume: 20 μL

Pre-developing solvent system: n-Hexane and tetradecane (95:5)

Solution A: 1 in 15 solution of ninhydrin in acetone

Developing solvent system: 0.1 M citric acid, 0.1 M dibasic sodium phosphate, and Solution A (60:40:1.5)

Spray reagent: 1 in 500 solution of ninhydrin in dehydrated alcohol. Protect this solution from light.

2.2 Analysis

Samples: Standard solution and Sample solution

Place the thin-layer chromatographic plate in a chamber containing the Pre-developing solvent system and allow the solvent front to move the length of the plate. Remove the plate from the chamber and allow the solvent to evaporate. Apply the Sample solution and Standard solution to the plate, allow the spots to dry, and develop the chromatogram in the Developing solvent system until the solvent front has moved three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow to air-dry. Spray the plate with the Spray reagent, dry for 10 min at 110°, and examine the chromatogram.

Acceptance criteria: The R value of the principal spot of the Sample solution corresponds to that of the Standard solution.

3 ASSAY

3.1 Procedure

Buffer: 6.86 g/L of monobasic potassium phosphate. Adjust with 10 N potassium hydroxide to a pH of 5.0.

Mobile phase: Acetonitrile and Buffer (40:960)

Standard solution: 1.06 mg/mL of USP Cefadroxil RS in Buffer. Use this solution on the day prepared. [Note—This solution contains the equivalent of 1 mg/mL of cefadroxil (C H N O S).]

Sample solution: Constitute a container of Cefadroxil for Oral Suspension as directed in the labeling. Dilute a portion of the resulting suspension with Buffer to prepare a solution containing nominally 1 mg/mL. Pass through a suitable filter of 0.8-μm or finer pore size, and use the filtrate. Use this solution on the day prepared.

3.2 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 230 nm

Column: 4-mm × 25-cm; packing L1

Flow rate: 1.5 mL/min

Injection size: 10 μL

3.3 System suitability

Sample: Standard solution

3.4 Suitability requirements

Capacity factor, k′: 2.0–3.5

Column efficiency: NLT 1800 theoretical plates

Tailing factor: NMT 2.2

Relative standard deviation: NMT 2.0%

3.5 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of cefadroxil (C₁₆H₁₇N₃O₅S) in the portion of Cefadroxil for Oral Suspension taken:

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

r_U = peak response of cefadroxil from the Sample solution

r_S = peak response of cefadroxil from the Standard solution

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

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

P = potency of cefadroxil in USP Cefadroxil RS (μg/mg)

F = conversion factor, 0.001 mg/μg

Acceptance criteria: 90.0%–120.0%

4 PERFORMANCE TESTS

Dissolution 〈711〉

Medium: Water; 900 mL

Apparatus 2: 25 rpm

Time: 30 min

Standard solution: USP Cefadroxil RS in Medium at a known concentration

Sample solution: Transfer 5.0 mL of the constituted Cefadroxil for Oral Suspension (weighed) to the dissolution vessel.

Analysis: Determine the amount of cefadroxil dissolved by employing UV absorption at the wavelength of 263 nm on the Sample solution in comparison with the Standard solution.

Calculate the amount of cefadroxil dissolved:

Result = (A_U/A_S) × (C_S/D) × V

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

C_S = concentration of the Standard solution (mg/mL)

V = volume of Medium, 900 mL

D = dilution factor

Tolerances: NLT 75% (Q) of the labeled amount of cefadroxil is dissolved.

Uniformity of Dosage Units 〈905〉

For solid packaged in single-unit containers: Meets the requirements

Deliverable Volume 〈698〉: Meets the requirements

5 SPECIFIC TESTS

pH 〈791〉: 4.5–6.0, in the suspension constituted as directed in the labeling

Water Determination, Method I〈921〉: NMT 2.0%, except where it is labeled as containing 100 mg of cefadroxil per mL after constitution, in which case the limit is NMT 3.0%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.

USP Reference Standards 〈11〉

USP Cefadroxil RS