Penicillin G Potassium 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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1 DEFINITION

Penicillin G Potassium Tablets contain NLT 90.0% and NMT 120.0% of the labeled number of Penicillin G Units.

2 IDENTIFICATION

A. Thin-Layer Chromatography

Diluent: Acetone, 0.1 M citric acid, and 0.1 M sodium citrate (2:1:1)

Standard solution: 12,000 Penicillin G Units/mL from USP Penicillin G Potassium RS in Diluent

Sample solution: Nominally 12,500 Penicillin G Units/mL from Tablets in Diluent. Pass through a suitable filter.

Chromatographic system

(See Chromatography 〈621〉, Thin-Layer Chromatography.)

Adsorbent: 0.25-mm layer of chromatographic silica gel mixture

Application volume: 20 μL

Developing solvent system: Toluene, dioxane, and glacial acetic acid (90:25:4)

Spray reagent 1: Starch TS

Spray reagent 2: Iodine TS diluted 1 in 10 with water

Analysis

Samples: Standard solution and Sample solution

Apply the Sample solution and the Standard solution to the plate, place in a suitable chromatographic chamber, and develop the chromatogram, using the Developing solvent system, until the solvent front has moved three-fourths of the length of the plate. Remove the plate from the chamber, mark the solvent front, and allow to air-dry. Spray the plate with Spray reagent 1 followed by Spray reagent 2.

Penicillin G appears as a white spot on a purple background.

Acceptance criteria: The R value of the penicillin G spot from the Sample solution corresponds to that from the Standard solution.

3 ASSAY

Procedure

Standard solution: Prepare as directed in Iodometric Assay—Antibiotics 〈425〉, Standard Preparation, using USP Penicillin G Potassium RS.

Sample solution: Nominally 2000 Penicillin G Units/mL, prepared as follows. Place NLT 5 Tablets in a high-speed glass blender jar containing a measured volume of Buffer B.1, and blend for 4 ± 1 min. Dilute a suitable aliquot with Buffer B.1.

Analysis: Proceed as directed in Iodometric Assay - Antibiotics 〈425〉, Procedure, using glass-stoppered, 125-mL conical flasks.

Calculate the percentage of the labeled number of Penicillin G Units in the portion of Tablets taken:

Result = (B − I) × (F/2) × (1/C_U) × 100

B = volume of 0.01 N sodium thiosulfate consumed in Blank Determination (mL)

I = volume of 0.01 N sodium thiosulfate consumed in Inactivation and Titration of the Sample solution (mL)

F = factor as calculated in Iodometric Assay—Antibiotics 〈425〉, Calculations

C_U = nominal concentration of penicillin G in the Sample solution (Penicillin G Units/mL)

Acceptance criteria: 90.0%–120.0%

4 PERFORMANCE TESTS

Dissolution 〈711〉

Medium: pH 6.0 phosphate buffer (see Reagents, Indicators, and Solutions—Buffer Solutions); 900 mL

Apparatus 2: 75 rpm

Time: 60 min

Standard solution: 400 Penicillin G Units/mL from USP Penicillin G Potassium RS in Medium

Sample solution: Use a filtered portion of the solution under test.

Solution A: A 1-in-1000 solution of polyoxyethylene (23) lauryl ether in water

Solution B: Dissolve 20 g of hydroxylamine hydrochloride in 5 mL of Solution A, and add water to make 1000 mL.

Buffer: 26 mg/mL of sodium hydroxide and 3.1 mg/mL of sodium acetate in water

Ferric nitrate solution: Suspend 233 g of ferric nitrate in about 600 mL of water, add 2.8 mL of sulfuric acid, stir until the ferric nitrate is dissolved, add 1 mL of polyoxyethylene (23) lauryl ether, dilute with water to 1000 mL, and mix.

Apparatus: Automatic analyzer (Figure 1) consisting of (1) a liquid sampler, (2) a proportioning pump, (3) suitable spectrophotometers equipped with matched flow cells and analysis capability at 480 nm, (4) a means of recording spectrophotometric readings and/or a computer for data retrieval and calculation, and (5) a manifold consisting of the components illustrated in the gure.

Analysis: With the sample line pumping water, the other lines pumping their respective reagents, and the spectrophotometer set at 480 nm, standardize the system until a steady absorbance baseline has been established. Transfer portions of the Standard solution and the Sample solution to sampler cups, and place in the sampler. Start the sampler, and conduct determinations of the Standard solution and the Sample solution, typically at the rate of 40 per h, using a ratio of about 2:1 for sample and wash time.

Calculate the percentage of the labeled amount of Penicillin G Units dissolved:

Result = (A_U/A_S) × C_S × V × (1/L) × 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

C_S = concentration of USP Penicillin G Potassium RS in the Standard solution (Penicillin G Units/mL)

V = volume of Medium, 900 mL

L = label claim (Penicillin G Units/Tablet)

Tolerances: NLT 70% (Q) of the labeled amount of Penicillin G Units is dissolved.

Uniformity of Dosage Units 〈905〉: Meet the requirements

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.

USP Reference Standards 〈11〉

USP Penicillin G Potassium RS