Action and use
Fluoroquinolone antibacterial.
DEFINITION
Enrofloxacin Oral Suspension contains Enrofloxacin.
The oral suspension complies with the requirements stated under Oral Liquids and with the following requirements.
Content of enrofloxacin, C19H22FN3O3
95.0 to 105.0% of the stated amount.
IDENTIFICATION
A. To a quantity of the oral suspension containing 0.1 g of Enrofloxacin, add 10 mL of dichloromethane, shake and allow to separate. Discard the upper aqueous layer and wash the lower dichloromethane layer with three 20-mL quantities of water. Dry the washed dichloromethane with sodium sulfate, filter and evaporate the filtrate to dryness. The infrared absorption spectrum of the dried residue, Appendix II A, is concordant with the reference spectrum of enrofloxacin (RSV 55).
B. In the Assay, 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
Dissolution
Comply with the dissolution test for tablets and capsules, Appendix XII B1.
TEST CONDITIONS
(a) Use Apparatus 2, rotating the paddle at 100 revolutions per minute.
(b) Use 500 mL of 0.1M hydrochloric acid, at a temperature of 37°, as the medium.
(b) Use a quantity of the oral suspension containing 25 mg of Enrofloxacin.
PROCEDURE
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) After 30 minutes withdraw a sample of the medium and filter. Dilute the filtrate with dissolution medium, if necessary, to produce a solution expected to contain 0.005% w/v of Enrofloxacin.
(2) 0.05% w/v of enrofloxacin BPCRS in a solution containing 2 volumes of acetonitrile and 3 volumes of 1M sulfuric acid. Dilute 1 volume of this solution to 10 volumes with 0.1M hydrochloric acid.
(3) 0.05% w/v of enrofloxacin BPCRS and 0.0005% w/v of ciprofloxacin hydrochloride BPCRS (impurity B).
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.0 mm) packed with octadecylsilyl silica gel for chromatography (10 μm) (Nucleosil RP18 is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 2.0 mL per minute.
(d) Use a column temperature of 40°.
(e) Use a detection wavelength of 278 nm.
(f) Inject 10 μL of each solution.
MOBILE PHASE
100 volumes of a solution containing 1.1% w/v of sodium heptanesulfonate monohydrate and 2.72% w/v of potassium dihydrogen orthophosphate, 215 volumes of acetonitrile and 685 volumes of water, adjust the pH of the mixture to 2.1 with orthophosphoric acid.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between the peaks corresponding to impurity B and enrofloxacin is at least 2.0.
DETERMINATION OF CONTENT
Calculate the total content of enrofloxacin, C19H22FN3O3, in the medium from the chromatograms obtained and using the declared content of C19H22FN3O3 in enrofloxacin BPCRS.
LIMITS
The amount of enrofloxacin released is not less than 75% (Q) of the stated amount.
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions prepared in a solution containing 2 volumes of acetonitrile and 3 volumes of 1M sulfuric acid.
(1) Disperse a quantity of the oral suspension containing 50 mg of Enrofloxacin in 10 mL of water, dilute to 100 mL and filter.
(2) Dilute 1 volume of solution (1) to 100 volumes.
(3) 0.05% w/v of enrofloxacin BPCRS and 0.0005% w/v of ciprofloxacin hydrochloride BPCRS (impurity B).
(4) Dilute 3 volumes of solution (2) to 10 volumes.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.0 mm) packed with octadecylsilyl silica gel for chromatography (10 μm) (Nucleosil RP18 is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1.5 mL per minute.
(d) Use a column temperature of 40°.
(e) Use a detection wavelength of 278 nm.
(f) Inject 5 μL of each solution.
(g) Allow the chromatography to proceed for 2.5 times the retention time of enrofloxacin.
MOBILE PHASE
Mobile phase 120 volumes of acetonitrile and 880 volumes of a 0.68% w/v solution of potassium dihydrogen orthophosphate previously adjusted to pH 2.1 with orthophosphoric acid.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between the peaks corresponding to impurity B and enrofloxacin is at least 2.0.
CALCULATION OF IMPURITIES
For each impurity, use the concentration of enrofloxacin in solution (2).
For the reporting threshold, use the concentration of enrofloxacin in solution (4).
For peak identification, use solution (3).
Enrofloxacin retention time: about 11 minutes.
Relative retention: impurity B, about 0.7.
LIMITS
— unspecified impurities: for each impurity, not more than 1.0%;
— total impurities: not more than 2.0%;
— reporting threshold: 0.3%.
ASSAY
Carry out the method for liquid chromatography, Appendix III D, using the following solutions prepared in a solution containing 2 volumes of acetonitrile and 3 volumes of 1M sulfuric acid.
(1) Disperse a weighed quantity of the oral suspension containing 50 mg of Enrofloxacin in 10 mL of water, dilute to 100 mL and filter.
(2) 0.05% w/v of enrofloxacin BPCRS.
(3) 0.05% w/v of enrofloxacin BPCRS and 0.0005% w/v of ciprofloxacin hydrochloride BPCRS (impurity B).
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions described under Related substances may be used.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between the peaks corresponding to impurity B and enrofloxacin is at least 2.0.
DETERMINATION OF CONTENT
Determine the weight per mL of the oral suspension, Appendix V G, and calculate the content of C19H22FN3O3 in the oral suspension from the chromatograms obtained and using the declared content of C19H22FN3O3 in enrofloxacin BPCRS.
IMPURITIES
The impurities limited by the requirements of this monograph include impurity B listed under Enrofloxacin.
