Neomycin Sulfate,Isoflupredone Acetate,and Tetracaine Hydrochloride Topical Powder, chemical structure, molecular formula, Reference Standards

Neomycin Sulfate,Isoflupredone Acetate,and Tetracaine Hydrochloride Topical Powder

»Neomycin Sulfate,Isoflupredone Acetate,and Tetracaine Hydrochloride Topical Powder contains the equivalent of not less than 90.0percent and not more than 125.0percent of the labeled amount of neomycin,and not less than 90.0percent and not more than 120.0percent of the labeled amounts of isoflupredone acetate (C23H29FO6)and tetracaine hydrochloride (C15H24N2O2·HCl).

Packaging and storage— Preserve in well-closed containers.

Labeling— Label it to indicate that it is intended for veterinary use only.

USP Reference standards á11ñ— USP Isoflupredone Acetate RS.USP Neomycin Sulfate RS.USP Tetracaine Hydrochloride RS.

Identification—

A: Thin-Layer Chromatographic Identification Test á201ñ—

Test solution— Add 20mLof chloroform to 1g of Topical Powder,shake for 5to 10minutes,and centrifuge.Evaporate a 10-mLportion of the clear solution to dryness,and dissolve the residue in 1mLof a mixture of chloroform and alcohol (1:1).

Standard solution: 0.5mg of USP Isoflupredone Acetate RSper mL,in a mixture of chloroform and alcohol (1:1).

Application volume: 30µL.

Developing solvent system: a mixture of methylene chloride and methanol (180:16),in a paper-lined chromatographic chamber.

Spray reagent: a solution of sulfuric acid in methanol (70in 100).

Procedure— Proceed as directed in the chapter,except to use a plate that has been activated by heating in an oven at 105

for 60minutes.Allow the plate to cool before using.Locate the spots under short-and long-wavelength UVlight.Spray the plate with Spray reagent,heat at 90

for 30minutes,and locate the spots under short-and long-wavelength UVlight (presence of isoflupredone acetate).

B: Thin-Layer Chromatographic Identification Test á201ñ—

Test solution— To 1g of Topical Powder in a centrifuge tube add 5mLof water,and shake until dissolved.Prepare a suspension of 10g of cation-exchange resin in 10mLof water,add 5mLof a solution of sodium hydroxide (1in 2),mix,and wash the resin with water until the pHof the wash is about 9.Add 0.3g of this suspension to the solution of Topical Powder,and shake for 10seconds.Centrifuge for 1minute,and discard the supernatant.Wash the resin in the tube with 10mLof water,centrifuge,and discard the supernatant.Add 2mLof 1Mammonium hydroxide,shake for 10seconds,and filter.Use the filtrate.

Standard solution,Application volume,Developing solvent system,Spray reagent,and Procedure— Proceed as directed in Identificationtest Aunder Neomycin Sulfate,Isoflupredone Acetate,and Tetracaine Hydrochloride Ointment (presence of neomycin).

Minimum fill á755ñ: meets the requirements.

Loss on drying á731ñ— Dry about 2g in vacuum at a pressure not exceeding 5mm of mercury at 60

for 3hours:it loses not more than 8.0%of its weight.

Assay for neomycin— Proceed as directed under Antibiotics—Microbial Assays á81ñ,the Test Dilutionbeing prepared as follows.Use an accurately weighed quantity of Topical Powder diluted quantitatively with Buffer No.3to obtain a solution having a suitable concentration of neomycin.Dilute this stock solution quantitatively with Buffer No.3to obtain a Test Dilutionhaving a concentration assumed to be equal to the median dose level of the Standard.

Assay for isoflupredone acetate—

Mobile phase,Diluent,Internal standard solution,Standard preparation,and Chromatographic system— Proceed as directed in the Assayunder Isoflupredone Acetate.

Assay preparation— Transfer an accurately weighed portion of Topical Powder,equivalent to about 4mg of isoflupredone acetate,to a suitable container.Add 8.0mLof Internal standard solution,32.0mLof Diluent,and about 10glass beads.Shake for about 15minutes,centrifuge,and use the clear chloroform portion.

Procedure— Proceed as directed in the Assayunder Isoflupredone Acetate.Calculate the quantity,in mg,of isoflupredone acetate (C23H29FO6)in the portion of Topical Powder taken by the formula:

WS(RU/RS),

in which the terms are as defined therein.

Assay for tetracaine hydrochloride—

Standard preparation— Prepare a solution having a known concentration of 5.5µg of USP Tetracaine Hydrochloride RSper mL.

Assay preparation— Transfer an accurately weighed portion of Topical Powder,equivalent to about 5.5mg of tetracaine hydrochloride,to a 100-mLvolumetric flask,dilute with water to volume,and mix.Pass about 30mLthrough a fine,sintered-glass filter.Transfer 10.0mLof the clear filtrate to a second 100-mLvolumetric flask,dilute with water to volume,and mix.

Procedure— Concomitantly determine the absorbances of the Standard preparationand the Assay preparationat the wavelength of maximum absorbance at about 310nm,with a suitable spectrophotometer,using water to zero the instrument.Calculate the quantity,in mg,of tetracaine hydrochloride (C15H24N2O2·HCl)in the portion of Topical Powder taken by the formula:

1000C(AU/AS),

in which Cis the concentration,in mg per mL,of USP Terracaine Hydrochloride RSin the Standard preparation;and AUand ASare the absorbances of the Assay preparationand the Standard preparation,respectively.

Auxiliary Information— Staff Liaison:Ian DeVeau,Ph.D.,Senior Scientist

Expert Committee:(VET)Veterinary Drugs

USP28–NF23Page 1350

Pharmacopeial Forum:Volume No.27(4)Page 2760

Phone Number:1-301-816-8178