Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Fluoroquinolone antibacterial.
DEFINITION
Levofloxacin Eye Drops are a sterile solution of Levofloxacin Hemihydrate in a suitable vehicle.
The eye drops comply with the requirements stated under Eye preparations and with the following requirements.
Content of levofloxacin, C18H20FN3O4
95.0 to 105.0% of the stated amount.
IDENTIFICATION
In the Assay, record the UV spectrum of the principal peak in the chromatograms obtained with solutions (1) and (2) with a diode array detector in the range of 210 to 400 nm.
The UV spectrum of the principal peak in the chromatogram obtained with solution (1) is concordant with that of the peak in the chromatogram obtained with solution (2);
the retention time of the principal peak in the chromatogram obtained with solution (1) is similar to that of the peak in the chromatogram obtained with solution (2).
TESTS
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions in the mobile phase.
(1) Shake a quantity of the eye drops containing the equivalent of 0.1 g of levofloxacin with 15 mL of 20% v/v of acetonitrile. Dilute with 20% v/v of acetonitrile to produce 50 mL and filter (0.45-μm pore size is suitable). Dilute 1 volume to 4 volumes.
(2) Dilute 1 volume of solution (1) to 200 volumes.
(3) Dissolve the contents of a vial of levofloxacin for system suitability EPCRS in 1 mL.
(4) Dilute 1 volume of solution (2) to 5 volumes.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with base-deactivated end-capped octadecylsilyl silica gel for chromatography (5 μm) (Inertsil ODS is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 0.8 mL per minute.
(d) Use a column temperature of 45°.
(e) Use a detection wavelength of 360 nm.
(f) Inject 25 μL of each solution.
(g) Allow the chromatography to proceed for three times the retention time of levofloxacin.
MOBILE PHASE
0.0874% w/v of copper sulphate pentahydrate, 0.091% w/v of isoleucine and 0.594% w/v of ammonium acetate in 30% v/v of methanol.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between the peaks due to impurities B and G is at least 1.5.
CALCULATION OF IMPURITIES
For all impurities, use the concentration of levofloxacin in solution (2).
For the reporting threshold, use the concentration of levofloxacin in solution (4).
For peak identification, use solution (3).
Levofloxacin retention time: about 20 minutes.
Relative retention: impurity E, about 0.4; impurity B, about 0.5; impurity G, about 0.56; impurity 1, about 0.63; impurity A, about 1.2.
Correction factors: impurity B, multiply by 1.3; impurity E, multiply by 1.7.
LIMITS
— impurity A: not more than 0.8%;
— unspecified impurities: for each impurity, not more than 0.2%;
— total unspecified impurities: not more than 1.0%;
— reporting threshold: 0.1%.
ASSAY
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) Shake a quantity of the eye drops containing 0.1 g of levofloxacin with 15 mL of 20% v/v of acetonitrile. Dilute with 20% v/v of acetonitrile to produce 100 mL and filter. Dilute 1 volume to 5 volumes with the mobile phase.
(2) 0.2% w/v of levofloxacin hemihydrate BPCRS in 20% v/v of acetonitrile, dissolved with the aid of ultrasound if necessary. Dilute 1 volume to 10 volumes with the mobile phase.
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions described under Related substances may be used.
DETERMINATION OF CONTENT
Calculate the content of C18H20FN3O4 in the eye drops using the declared content of C18H20FN3O4,1⁄2H2O in levofloxacin hemihydrate BPCRS. Each mg of C18H20FN3O4,1⁄2H2O is equivalent to 0.9757 mg of C18H20FN3O4.
STORAGE
Levofloxacin Eye Drops should be kept in an airtight container and protected from light.
LABELLING
The quantity of active ingredient is stated in terms of the equivalent amount of levofloxacin.
IMPURITIES
The impurities limited by the requirements of this monograph include impurities A, B, C, D, E, G, H and I listed under Levofloxacin Hemihydrate and:
1. (S)-4-(6-Carboxy-9-fluoro-2,3-dihydro-3-methyl-7-oxo-7H-pyrido-[1,2,3-de][1,4]benzoxazine-10-yl)-1-methylpiperazine 1-oxide (N-Oxide)
