Penicillin G Procaine and Novobiocin Sodium Intramammary Infusion

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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Penicillin G Procaine and Novobiocin Sodium Intramammary Infusion is a suspension of Penicillin G Procaine and Novobiocin Sodium in a suitable vegetable oil vehicle. It contains a suitable preservative and suspending agent. It contains not less than 90.0 percent and not more than 125.0 percent of the labeled amounts of Penicillin G Units and novobiocin (C₃₁H₃₆N₂O₁₁).

1 Packaging and storage

Preserve in disposable syringes that are well-closed containers.

2 Labeling

Label it to indicate that it is for veterinary use only.

USP Reference standards 〈11〉

USP Novobiocin RS

USP Penicillin G Potassium RS

Water Determination, Method I 〈921〉: not more than 1.0%, 20 mL of a mixture of toluene and methanol (7:3) being used in place of methanol in the titration vessel.

3 Assay for penicillin G

Proceed as directed for penicillin G under Antibiotics—Microbial Assays 〈81〉, except to use Staphylococcus aureus ATCC No. 12692 as the test organism. Prepare the inoculum by growing the organism at 32° to 35° for 24 hours on Medium 1 to which has been added a solution of novobiocin sodium, containing the equivalent of 2.5 mg of novobiocin per mL that has been filtered through a membrane filter having a 0.2-μm porosity, so that the medium contains the equivalent of 10 μg of novobiocin per mL. Use an inoculum composition of about 5 mL of stock suspension in each 100 mL of Medium 1. Expel the contents of a syringe of Intramammary Infusion into a high-speed glass blender jar containing 1.0 mL of Polysorbate 80 and 499.0 mL of Buffer B.1, and blend for 3 to 5 minutes. Allow to stand for 10 minutes, and dilute an accurately measured volume of the aqueous phase quantitatively and stepwise with Buffer B.1 to obtain a Test Dilution having a concentration of penicillin G assumed to be equal to the median dose level of the Standard.

4 Assay for novobiocin

Proceed as directed for novobiocin under Antibiotics—Microbial Assays 〈81〉, expelling the contents of a syringe of Intramammary Infusion into a high-speed blender jar containing 1.0 mL of polysorbate 80 and 499.0 mL of Buffer B.3, and blend for 3 to 5 minutes. Allow to stand for 10 minutes. To an accurately measured volume of the aqueous phase add sufficient penicillinase to inactivate the penicillin G therein, and dilute quantitatively and stepwise with Buffer B.6 to obtain a Test Dilution having a concentration of novobiocin assumed to be equal to the median dose level of the Standard. [Note - Store this Test Dilution at 37° for 30 minutes and allow to cool before using it to fill the cylinders on the plates.]