Gentamicin Sulfate

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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Gentamicin sulfate (salt);

Gentamycin sulfate

CAS RN®: 1405-41-0; UNII: 8X7386QRLV.

1 DEFINITION

Gentamicin Sulfate is the sulfate salt, or a mixture of such salts, of the antibiotic substances produced by the growth of Micromonospora purpurea. It has a potency equivalent to NLT 590 μg/mg of gentamicin, calculated on the dried basis.

2 IDENTIFICATION

Change to read:

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K (CN 1-May-2020)

B. Identification Tests - General, Sulfate 〈191〉

3 ASSAY

Procedure

Analysis: Proceed as directed for Gentamicin under Antibiotics—Microbial Assays 〈81〉.

Acceptance criteria: NLT 590 μg/mg of gentamicin, calculated on the dried basis

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 1.0%

Limit of Methanol (if present)

Internal standard solution: 0.50% v/v of n-propyl alcohol

Standard solution: 0.25% v/v each of methanol and n-propyl alcohol

Control solution: 250 mg/mL of Gentamicin Sulfate

Sample solution: 250 mg/mL of Gentamicin Sulfate in a mixture of Internal standard solution and water (1:1)

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 4-mm × 1.5-m; packed with support S3

Temperature

Column: Constant temperature between 120° and 140°

Injector: Constant temperature at least 50° higher than the column temperature

Detector: Constant temperature at least 50° higher than the column temperature

Carrier gas: Nitrogen

Flow rate: Constant flow rate between 30 and 40 mL/min

Injection type: Syringe with a polytef-tipped plunger

Injection volume: 2 μL

System suitability

Sample: Standard solution

Suitability requirements

Resolution: NLT 1.0 between n-propyl alcohol and methanol

Analysis

Samples: Standard solution, Sample solution, and Control solution

Chromatograph the Control solution, and examine the chromatogram: if any peak is observed at a retention time corresponding to that of n-propyl alcohol, use the response of that peak to correct the n-propyl alcohol peak response of the Sample solution.

Calculate the percentage of methanol in the Gentamicin Sulfate taken:

Result = (R_U/R_S) × (C_S/C_U) × D × F

R_U = peak area response of methanol to n-propyl alcohol (corrected for any peak at the locus of the n-propyl alcohol peak in the Control solution) from the Sample solution

R_S = peak area response of methanol to n-propyl alcohol from the Standard solution

C_S = percentage of methanol in the Standard solution

C_U = concentration of Gentamicin Sulfate in the Sample solution (mg/mL)

D = density of methanol (g/mL)

F = conversion factor, 1000 mg/g

Acceptance criteria: NMT 1.0%

5 SPECIFIC TESTS

5.1 Content of Gentamicins

Mobile phase: To 900 mL of carbonate-free water, add 7 mL of trifluoroacetic acid, 250 μL of pentafluoropropanoic acid, and 4 mL of 12.5 M sodium hydroxide (carbonate-free). Allow to equilibrate, and adjust with 0.5 M sodium hydroxide (carbonate-free) to a pH of 2.6. Add 15 mL of acetonitrile, and dilute with carbonate-free water to 1 L. If necessary, adjust the volume of acetonitrile in the Mobile phase. A total volume of up to 50 mL can be added per L of Mobile phase.

System suitability solution: 100 μg/mL of USP Gentamicin Sulfate RS and 20 μg/mL of USP Sisomicin Sulfate RS in Mobile phase

Sample solution: 0.2 mg/mL of Gentamicin Sulfate in Mobile phase

5.1.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: Pulsed amperometric electrochemical detector

Indicator electrode: Gold

Reference electrode: Silver–silver chloride

Auxiliary electrode: Stainless steel. [Note—If the cell body is made of stainless steel, it can be used as the auxiliary electrode.]

Waveform: See Table 1.

Table 1

Column: 4.6-mm × 25-cm; 5-μm packing L1

Column temperature: 35°

Flow rate: 1 mL/min

Post-column reagent: 20 g/L sodium hydroxide (carbonate-free), degassed and introduced pulselessly using a 375-μL polymeric mixing coil. [Note-A suitable mixing coil is the knitted reaction coil, part number 043700, available from Dionex Corporation (www.dionex.com).]

Flow rate of post-column reagent: 0.3 mL/min

Injection volume: 20 μL

Run time: 1.2 times the retention time of gentamicin C

5.1.2 System suitability

Sample: System suitability solution

5.1.3 Suitability requirements

Resolution: NLT 1.5 between gentamicin C and gentamicin C

5.1.4 Analysis

Sample: Sample solution

Calculate the percentage of each gentamicin in the portion of Gentamicin Sulfate taken:

Result = (r_U/r_T) × 100

r_U = peak area response corresponding to the particular gentamicin

r_T = sum of the area responses of the gentamicin C_1a, gentamicin C₂, gentamicin C_2a, gentamicin C_2b, and gentamicin C₁ peaks

Acceptance criteria: Identify peaks by the relative retention times in Table 2.

Table 2

^a These compounds are listed for information only and are not to be reported in this test.

^b 4-O-[3-Deoxy-4-C-methyl-3-(methylamino)-β-l-arabinopyranosyl]-2-deoxy-l-streptamine.

^c O-3-Deoxy-4-C-methyl-3-(methylamino)-β-l-arabinopyranosyl-(1→4)-O-[2,6-diamino-2,3,4,6-tetradeoxy-α-d-glycero-hex-4-enopyranosyl-(1→6)]-2-deoxy-d-streptamine.

^d The limit is for the sum of gentamicin C and gentamicin C .

^e The limit is for the sum of gentamicin C and gentamicin C .

5.2 Optical Rotation, Specific Rotation

Sample solution: 10 mg/mL

Acceptance criteria: +107° to +121°

pH 〈791〉

Sample solution: 40 mg/mL

Acceptance criteria: 3.5–5.5

5.3 Loss on Drying

Analysis: Dry it in vacuum at a pressure NMT 5 mm of mercury at 110° for 3 h.

Acceptance criteria: NMT 18.0%

Sterility Tests 〈71〉: Where the label states that Gentamicin Sulfate is sterile, it meets the requirements.

Bacterial Endotoxins Test 〈85〉: Where the label states that Gentamicin Sulfate is sterile or must be subjected to further processing during the preparation of injectable dosage forms, it contains NMT 0.71 USP Endotoxin Unit/mg of gentamicin.

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.

Labeling: Where it is intended for use in preparing injectable dosage forms, the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms.

USP Reference Standards 〈11〉

USP Gentamicin Sulfate RS

USP Sisomicin Sulfate RS