Orbifloxacin Tablets

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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Orbifloxacin Tablets contain not less than 90.0 percent and not more than 110.0 percent of the labeled amount of orbifloxacin (C₁₉H₂₀F₃N₃O₃).

1 Packaging and storage

Preserve in tight containers, and store between 2° and 30°.

2 Labeling

Label to indicate that it is for veterinary use only.

USP Reference standards 〈11〉

USP Orbifloxacin RS

3 Identification

A: Thin-Layer Chromatographic Identification Test 〈201〉.

Absorbent: silica gel.

Diluent: a mixture of chloroform, methanol, and glacial acetic acid (8:1:1).

Test solution - Crush 1 Tablet and transfer into a centrifuge tube. Add Diluent quantitatively, and mix to obtain a final concentration of about 0.56 mg per mL of orbifloxacin. Centrifuge the solution.

Standard solution - Prepare a solution of USP Orbifloxacin RS in Diluent having a concentration of about 0.56 mg per mL.

Application volume: 5 μL

Developing solvent system: a mixture of chloroform, methanol, water, and ammonium hydroxide (18:7:1:0.02).

B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the

Standard preparation, as obtained in the Assay.

Dissolution 〈711〉

Medium: 0.1 N hydrochloric acid; 1000 mL.

Apparatus 2: 50 rpm.

Time: 30 minutes.

Determine the amount of C₁₉H₂₀F₃N₃O₃ dissolved by employing the following procedure.

Standard solution - Prepare a solution of USP Orbifloxacin RS in Medium with a

nal concentration of about L/100, where L is the Tablet label claim in mg. Transfer 10.0 mL of this solution to a 100-mL volumetric flask, dilute with Medium to volume, and mix.

Test solution - Pass a portion of the solution under test through a suitable 0.8-μm filter, discarding the first 3 mL.

Procedure - Determine the amount of C H F N O dissolved by employing UV absorption at the wavelength of maximum absorbance at about 291 nm on portions of the Test solution in comparison with the Standard solution using Medium as blank. Calculate the amount of orbifloxacin dissolved by the formula:

100,000(A_U/A_S)(C_S/L)

in which A_U and A_S are the absorbances obtained with the Test solution and the Standard solution, respectively; C_S is the concentration, in mg per mL, of orbifloxacin in the Standard solution; and L is the Tablet label claim in mg.

Tolerances - Not less than 80% (Q) of the labeled amount of C H F N O is dissolved in 30 minutes.

Uniformity of dosage units 〈905〉: meet the requirements.

Water Determination, Method Ic 〈921〉: between 3.5% and 7.0%.

Test preparation - Accurately weigh 5 Tablets, and transfer into a 50-mL centrifuge tube. Add 25 mL of anhydrous methanol, and cap.

Blank: 25 mL of anhydrous methanol in a 50-mL centrifuge tube.

Procedure - Rotate the Test preparation and the Blank for 16 hours. Centrifuge. Titrate an equal volume of the Test preparation and the Blank so that the amount of water titrated will be approximately 1000 μg to 1500 μg.

4 Chromatographic purity

Buffer, Mobile phase, Standard preparation, System suitability preparation, and Chromatographic system - Prepare as directed in the Assay.

Standard solution - Dilute quantitatively with Buffer the Standard preparation to obtain a solution having a known concentration of about 0.00004 mg per mL.

Test solution - Transfer 10 Tablets into a volumetric flask. Add Buffer to fill the flask about 70%, shake for 2 hours, and sonicate for 5 minutes.

Dilute quantitatively, and stepwise if necessary, with Buffer to obtain a solution having a concentration of about 0.22 mg per mL. Pass a portion of the solution through a 0.8-μm filter.

Chromatographic system (see Chromatography 〈621〉) - Inject the Buffer as directed for Procedure to verify that there are no interfering peaks.

Procedure - Separately inject equal volumes (about 10 μL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the area responses for the major peaks. Calculate the percentage of related compounds in the portion of

Tablets taken by the formula:

100(C_S/C )(r_i/r_S)(1/F)

in which C_S is the concentration, in mg per mL, of USP Orbifloxacin RS in the Standard solution; C is the concentration, in mg per mL, of the

Test solution; r_i is the peak area response for each impurity obtained from the Test solution; r is the peak area response for the orbifloxacin peak obtained from the Standard solution; and F is the relative response factor for each impurity, as presented in Table 1.

Table 1

5 Assay

Buffer - In a 2-L flask, dissolve about 11.8 g of sodium citrate in 1600 mL of water, and mix. Add 180 mL of glacial acetic acid, and mix. Adjust with 6 N sodium hydroxide to a pH of 3.5, dilute with water to volume, and mix.

Mobile phase - Prepare a filtered and degassed mixture of Buffer, methanol, and dioxane (91:6:4). Make adjustments if necessary (see System Suitability under Chromatography 〈621〉).

Standard stock preparation - Dissolve an accurately weighed quantity of USP Orbifloxacin RS in Buffer, and dilute quantitatively, and stepwise if necessary, with Buffer to obtain a solution having a known concentration of about 0.2 mg per mL.

Standard preparation - Accurately transfer a quantity of Standard stock preparation and dilute quantitatively, and stepwise if necessary, with Buffer to obtain a solution having a known concentration of about 0.02 mg per mL.

System suitability preparation - Dissolve about 40 mg of methyl 4-aminobenzoate in 2 mL of methanol, and dilute with Buffer to 200 mL. Pipet 10.0 mL of this solution and 10.0 mL of the Standard stock preparation into a 100-mL volumetric flask. Dilute with Buffer to volume, and mix.

Assay preparation - Transfer 10 Tablets into a volumetric flask. Add Buffer to fill the flask about 70%, shake for 2 hours, and sonicate for 5 minutes. Dilute quantitatively, and stepwise if necessary, with Buffer to obtain a solution having a known concentration of about 0.02 mg per mL. Pass a portion of the solution through a 0.8-μm filter.

Chromatographic system (see Chromatography 〈621〉) - The liquid chromatograph is equipped with a 290-nm detector and 4.6-mm × 3-cm column that contains 3-μm packing L1. The flow rate is about 0.8 mL per minute. Chromatograph the System suitability preparation, and record the peak response as directed for Procedure: the relative retention times are about 1.3 for methyl 4-aminobenzoate and 1.0 for orbifloxacin; the resolution, R, between methyl 4-aminobenzoate and orbifloxacin is not less than 2; the tailing factor is not more than 1.8; and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure - Separately inject equal volumes (about 10 μL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the area responses for the major peaks. Calculate the quantity, in mg, of orbifloxacin (C₁₉H₂₀F₃N₃O₃) in the portion of Tablets taken by the formula:

C(D_U)(r_U/r_S)

in which C is the concentration, in mg per mL, of USP Orbifloxacin RS in the Standard preparation; D_U is the dilution factor of the Assay preparation, in mL; and r_U and r_S are the peak area responses obtained from the Assay preparation and the Standard preparation, respectively.