Ciprofloxacin Ophthalmic Solution
Ciprofloxacin Ophthalmic Solution is a sterile, aqueous solution of Ciprofloxacin Hydrochloride. It contains NLT 90.0% and NMT 110.0% of the labeled amount of ciprofloxacin (C17H18FN3O3).
•   The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
•  Procedure
Solution A:  0.005 M tetrabutylammonium phosphate solution. Adjust with phosphoric acid to a pH of 2.0.
Mobile phase:  Methanol and Solution A (1:3)
Standard solution:  0.14 mg/mL of USP Ciprofloxacin Hydrochloride RS in water
System suitability solution:  0.01 mg/mL of USP Ciprofloxacin Ethylenediamine Analog RS in Standard solution
Sample solution:  Equivalent to 0.12 mg/mL of ciprofloxacin from Ophthalmic Solution, in water
Chromatographic system 
Mode:  LC
Detector:  UV 280 nm
Column:  4.6-mm × 25-cm; packing L1
Flow rate:  1.5 mL/min
Injection size:  20 µL
System suitability 
Samples:  Standard solution and System suitability solution
[Note—The relative retention times for the ciprofloxacin ethylenediamine analog and ciprofloxacin are 0.8 and 1.0, respectively. ]
Suitability requirements 
Resolution:  NLT 1.5 between the ciprofloxacin ethylenediamine analog and ciprofloxacin, System suitability solution
Capacity factor:  1.5–6 for the ciprofloxacin peak, Standard solution
Column efficiency:  NLT 500 theoretical plates, Standard solution
Tailing factor:  0.9–2.0, Standard solution
Relative standard deviation:  NMT 2%, Standard solution
Samples:  Standard solution and Sample solution
Calculate the percentage of the labeled amount of C17H18FN3O3 in the portion of Ophthalmic Solution taken:
Result = (rU/rS) × (CS/CU) × (Mr1/Mr2) × 100
rU== peak response from the Sample solution
rS== peak response from the Standard solution
CS== concentration of USP Ciprofloxacin Hydrochloride RS in the Standard solution (mg/mL)
CU== nominal concentration of ciprofloxacin in the Sample solution (mg/mL)
Mr1== molecular weight of ciprofloxacin, 331.34
Mr2== molecular weight of anhydrous ciprofloxacin hydrochloride, 367.81
Acceptance criteria:  90.0%–110.0%
•  pH 791: 3.5–5.5
•  Sterility Tests 71: It meets the requirements when tested as directed under Test for Sterility of the Product to Be Examined, Membrane Filtration.
•  Packaging and Storage: Preserve in tight containers, protected from light, at room temperature.
•  USP Reference Standards 11
USP Ciprofloxacin Ethylenediamine Analog RS Click to View Structure
1-Cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-[(2-aminoethyl)amino]-3-quinolinecarboxylic acid hydrochloride.
    C15H16FN3O3·HCl         341.77
USP Ciprofloxacin Hydrochloride RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Behnam Davani, Ph.D., M.B.A.
Senior Scientific Liaison
(SM12010) Monographs - Small Molecules 1
71 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
(GCM2010) General Chapters - Microbiology
Reference Standards RS Technical Services
USP35–NF30 Page 2675
Pharmacopeial Forum: Volume No. 35(4) Page 842