Amoxicillin for Oral Suspension
Amoxicillin for Oral Suspension contains the equivalent of NLT 90.0% and NMT 120.0% of the labeled amount of amoxicillin (C16H19N3O5S). It contains one or more suitable buffers, colors, flavors, preservatives, stabilizers, sweeteners, and suspending agents.
•  The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
•  Procedure
Buffer:  Dissolve 6.8 g/L of monobasic potassium phosphate in water. Adjust with a 45% (w/w) solution of potassium hydroxide to a pH of 5.0 ± 0.1.
Mobile phase:  Acetonitrile and Buffer (1:24)
Standard solution:  1.2 mg/mL of USP Amoxicillin RS in Buffer. [Note—Use this solution within 6 h. ]
Sample solution:  Dilute a measured volume of Amoxicillin for Oral Suspension, constituted as directed in the labeling, freshly mixed and free from air bubbles, quantitatively and stepwise in Buffer to obtain a solution containing nominally 1 mg/mL of anhydrous amoxicillin. Pass a portion of this solution through a suitable filter. [Note—Use this solution within 6 h. ]
Chromatographic system 
Mode:  LC
Detector:  UV 230 nm
Column:  4-mm × 25-cm;10-µm packing L1
Flow rate:  1.5 mL/min
Injection size:  10 µL
System suitability 
Sample:  Standard solution
Suitability requirements 
Tailing factor:  NMT 2.5
Relative standard deviation:  NMT 2.0%
Samples:  Standard solution and Sample solution
Calculate the percentage of C16H19N3O5S in the Amoxicillin for Oral Suspension taken:
Result = (rU/rS) × (CS/CU) × P × F × 100
rU== peak response from the Sample solution
rS== peak response from the Standard solution
CS== concentration of USP Amoxicillin RS in the Standard solution (mg/mL)
CU== nominal concentration of anhydrous amoxicillin in the Sample solution (mg/mL)
P== potency of amoxicillin in USP Amoxicillin RS (µg/mg)
F== conversion factor, 0.001 mg/µg
Acceptance criteria:  90.0%–120.0%
•  Uniformity of Dosage Units 905
For solids packaged in single-unit containers: Meets the requirements
•  Deliverable Volume 698: Meets the requirements
•  pH 791: 5.0–7.5, in the suspension constituted as directed in the labeling
•  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.
•  Packaging and Storage: Preserve in tight containers, and store at controlled room temperature.
•  USP Reference Standards 11
USP Amoxicillin RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Ahalya Wise, M.S.
Senior Scientific Liaison
(SM12010) Monographs - Small Molecules 1
61 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
(GCM2010) General Chapters - Microbiology
62 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
(GCM2010) General Chapters - Microbiology
Reference Standards RS Technical Services
USP35–NF30 Page 2202
Pharmacopeial Forum: Volume No. 36(4) Page 894