Penicillin G Procaine and Dihydrostreptomycin Sulfate 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 Dihydrostreptomycin Sulfate Intramammary Infusion is a suspension of Penicillin G Procaine and Dihydrostreptomycin Sulfate in a suitable vegetable oil vehicle. It may contain suitable gelling and thickening agents. It contains not less than 90.0 percent and not more than 120.0 percent of the labeled amounts of Penicillin G Units and of dihydrostreptomycin (C₂₁H₄₁N₇O₁₂).

1 Packaging and storage

Preserve in well-closed, disposable syringes.

2 Labeling

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

USP Reference standards 〈11〉

USP Dihydrostreptomycin Sulfate RS

USP Penicillin G Potassium RS

USP Penicillin G Procaine RS

3 Identification

A: It responds to the Identification test under Penicillin G Procaine Intramammary Infusion.

B: Place a portion of it, equivalent to about 100 mg of dihydrostreptomycin, in a separator, add 20 mL of chloroform and 20 mL of water, and shake by mechanical means for 15 minutes. Allow to separate, and discard the lower chloroform layer. Repeat the extraction with a 20-mL portion of chloroform, discarding the chloroform layer. Use the aqueous layer as the test solution. Prepare a Standard solution of USP Dihydrostreptomycin Sulfate RS in water containing 6.5 mg per mL. Apply separately 30 μL of each solution to a thin-layer chromatographic plate (see Chromatography 〈621〉) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of n-propyl alcohol, water, pyridine, and glacial acetic acid (15:12:10:2) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Spray the plate with a reagent prepared by dissolving 2 g of ninhydrin in 100 mL of alcohol and adding 20 mL of glacial acetic acid, heat the plate at 110° for 10 minutes, and examine the chromatograms: the R value and color of the principal spot obtained from the test solution correspond to those obtained from the Standard solution.

Water Determination, Method I 〈921〉: not more than 1.4%, 20 mL of a mixture of toluene and methanol (7:3) being used in the titration vessel in place of methanol.

4 Assay for penicillin G

Proceed as directed for penicillin G under Antibiotics - Microbial Assays 〈81〉, expelling the contents of 1 syringe of Intramammary Infusion into a high-speed glass blender jar containing 499.0 mL of Buffer B.1 and 1.0 mL of Polysorbate 80, and blending for 3 to 5 minutes. Allow to stand for about 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.

5 Assay for dihydrostreptomycin

Proceed as directed for the cylinder-plate assay for dihydrostreptomycin under Antibiotics - Microbial Assays 〈81〉, expelling the contents of 1 syringe of Intramammary Infusion into a high-speed glass blender jar containing 499.0 mL of Buffer B.3 and 1.0 mL of polysorbate 80, and blending for 3 to 5 minutes. Allow to stand for about 10 minutes, and to an accurately measured volume of the aqueous phase add an accurately measured volume of penicillinase sufficient to inactivate the penicillin G contained therein. Dilute this solution quantitatively with Buffer B.3 to obtain a Test Dilution having a concentration of dihydrostreptomycin assumed to be equal to the median dose level of the Standard, and store at 37° for 30 minutes before filling the cylinders.