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4250 Penicillin / Official Monographs USP 35 lin G Units, in the portion of Injectable Suspension taken by the USP Reference standards 〈11〉— formula: USP Hydrocortisone Acetate RS USP Neomycin Sulfate RS (L / 2D)(F)(B − I) USP Penicillin G Potassium RS USP Polymyxin B Sulfate RS in which L is the labeled quantity, in Penicillin G Units, in the Water, Method I 〈921〉: not more than 1.0%, 20 mL of a volume of Injectable Suspension taken, D is the concentration, mixture of toluene and methanol (7:3) being used in place of in Penicillin G Units per mL, of the Assay preparation, on the methanol in the titration vessel. basis of the labeled quantity in the portion of Injectable Suspen- sion taken and the extent of dilution, and the other terms are Assay for penicillin G—Proceed as directed for penicillin G as defined therein. under Antibiotics—Microbial Assays 〈81〉, using an accurately measured volume of Topical Suspension blended for 2 minutes Assay for dihydrostreptomycin—Proceed as directed for the in a high-speed glass blender jar with 499.0 mL of Buffer No. 1 turbidimetric assay for dihydrostreptomycin as directed under and 1.0 mL of polysorbate 80. Allow to stand for 10 minutes, Antibiotics—Microbial Assays 〈81〉, using an accurately measured and dilute an accurately measured volume of the aqueous volume of Injectable Suspension diluted quantitatively with phase quantitatively and stepwise with Buffer No. 1 to obtain a water to yield a Test Dilution having a concentration assumed to Test Dilution having a concentration of penicillin G assumed to be equal to the median dose level of the Standard. be equal to the median dose level of the Standard. Assay for prednisolone— Assay for neomycin—Proceed as directed for neomycin under Standard preparation—Prepare as directed for Standard Prep- Antibiotics—Microbial Assays 〈81〉, using an accurately measured aration under Single-steroid Assay 〈511〉, using USP Prednisolone volume of Topical Suspension shaken in a separator with about RS. 50 mL of ether, and extracted with four 20-mL portions of Assay preparation—Transfer to a separator an accurately Buffer No. 3. Combine the aqueous extracts, and dilute with measured volume of Injectable Suspension, and add 15 mL of Buffer No. 3 to an appropriate volume to obtain a stock solu- water. Extract with three 25-mL portions and finally with one tion. To an accurately measured volume of this stock solution 20-mL portion of chloroform, filtering each portion through add an accurately measured volume of penicillinase sufficient to chloroform-washed cotton into a 100-mL volumetric flask. Add inactivate the penicillin G therein, heat at 37° for 30 minutes, chloroform to volume, and mix. Pipet 20 mL of this solution and dilute quantitatively and stepwise with Buffer No. 3 to ob- into a suitable glass-stoppered flask or tube, evaporate the chlo- tain a Test Dilution having a concentration of neomycin as- roform on a steam bath just to dryness, cool, and dissolve the sumed to be equal to the median dose level of the Standard. residue in 2.0 mL, accurately measured, of a mixture of equal Assay for polymyxin B—Proceed as directed for polymyxin B volumes of chloroform and alcohol. under Antibiotics—Microbial Assays 〈81〉, using an accurately Procedure—Proceed as directed for Single-Steroid Assay 〈511〉, measured volume of Topical Suspension blended for 2 minutes using Solvent A to develop the chromatogram. Calculate the in a high-speed glass blender jar containing 499.0 mL of Buffer quantity, in mg, of prednisolone (C21H28O5) in each mL of the No. 6 and 1.0 mL of polysorbate 80. Allow to stand for 10 Injectable Suspension taken by the formula: minutes, and to an accurately measured volume of the aqueous phase add an accurately measured volume of penicillinase suffi- 0.01(C / V)(AU / AS) cient to inactivate the penicillin G therein. Heat the solution at 37° for 30 minutes, and dilute quantitatively and stepwise with in which the terms are as defined therein. Buffer No. 6 to obtain a Test Dilution having a concentration of polymyxin assumed to be equal to the median dose level of the Standard. Add to each test dilution of the Standard a quantity of USP Neomycin Sulfate RS dissolved in Buffer No. 6 to obtain . the same concentration of neomycin present in the Test Penicillin G Procaine, Neomycin and Dilution. Polymyxin B Sulfates, and Assay for hydrocortisone acetate—Using an accurately Hydrocortisone Acetate Topical measured volume of Topical Suspension, proceed as directed in Suspension the Assay under Hydrocortisone Acetate Lotion. » Penicillin G Procaine, Neomycin and Polymyxin

B Sulfates, and Hydrocortisone Acetate Topical . Suspension is a suspension of Penicillin G Pro- Penicillin G Procaine and Novobiocin caine, Neomycin Sulfate, Polymyxin B Sulfate and Sodium Intramammary Infusion Hydrocortisone Acetate in Peanut Oil or Sesame Oil. It may contain one or more suitable dispers- » Penicillin G Procaine and Novobiocin Sodium ing and suspending agents. It contains not less Intramammary Infusion is a suspension of Penicil- than 90.0 percent and not more than 140.0 per- lin G Procaine and Novobiocin Sodium in a suita- cent of the labeled amounts of Penicillin G Units, ble vegetable oil vehicle. It contains a suitable of neomycin, and of polymyxin B Units, and not preservative and suspending agent. It contains less than 90.0 percent and not more than 110.0 not less than 90.0 percent and not more than percent of the labeled amount of hydrocortisone 125.0 percent of the labeled amounts of Penicil- acetate (C23H32O6). lin G Units and novobiocin (C31H36N2O11). Packaging and storage—Preserve in well-closed containers. Packaging and storage—Preserve in disposable syringes that are well-closed containers. Labeling—Label it to indicate that it is intended for veterinary use only. Labeling—Label it to indicate that it is for veterinary use only. USP Reference standards 〈11〉— USP Novobiocin RS USP Penicillin G Potassium RS

Official from May 1, 2012 Copyright (c) 2011 The United States Pharmacopeial Convention. All rights reserved.