Gentamicin Sulfate is the sulfate of a mixture of aminoglycoside substances having antibacterial activity produced by the growth of Micromonospora purpurea or Micromonospora echinospora.
Gentamicin Sulfate occurs as a white to light yellowish white powder. It is highly hygroscopic.
It contains not less than 590 mg (potency) and not more than 775 mg (potency) per mg, calculated on the dried basis. The potency of Gentamicin Sulfate is expressed as mass (potency) of gentamicin C1
- Soluble in water.
- Typically insoluble in ethanol. (96%)
IDENTIFICATION BY PPT. FORMATION:
Dissolve 50 mg of Gentamicin Sulfate in 5 mL of water, and add 0.5 mL of barium chloride TS: a white precipitate is formed.
COLOR OF SOLUTION:
Dissolve 1.0g of Gentamicin Sulfate in 10 mL of water, the solution is clear and colorless to pale yellow.
IDENTIFICATION BY THIN LAYER CHROMATOGRAPHY:
Dissolve 50 mg each of Gentamicin Sulfate and Gentamicin Sulfate Reference Standard in 10 mL of water, and use both of these solutions as the sample solution and standard solution. Perform the test with these solutions as directed under thin layer-Chromatography. Spot 20 µL of the sample solution and standard solution on a plate of silica gel for thin layer-Chromatography. Separately, shake a mixture of chloroform, ammonia solution and methanol in ration of (2:1:1) in a separator, and allow the mixture to stand for more than 1 hour. To 20 mL of the lower layer so obtained add 0.5 mL of methanol, and use this as the developing solvent. Develop the plate with the developing solvent to a distance of about 17cm in a developing container with a cover, having an opening of about 20 mm2, and without putting a filter paper in the container, and air-dry the plate. Allow the plate to stand in iodine vapors: three principal spots obtained from the sample solution are the same with the corresponding spots obtained from the standard solution in color tone and the Rf value, respectively.
The pH of a solution obtained by dissolving 400 mg of Gentamicin Sulfate in 10 mL of water is between 3.5 and 5.5
LOSS ON DRYING:
Not more than 18.0% when 0.15g of Gentamicin Sulfate at pressure not exceeding 0.67 kPa and temperature 110°C for 3 hours. Handle the sample avoiding absorption of moisture.
RESIDUE ON IGNITION:
Should be not more than 1.0% when 1.0 gram is ignited.
SPECIFIC OPTICAL ROTATION:
+107° to +121° When 100mg of Gentamicin Sulfate is dissolved in 10ml of water.
QUANTITATIVE ASSAY (BIO-ASSAY):
Perform the test according to the Cylinder-plate method as directed under Microbial Assay for Antibiotics according to the following conditions.
Test organism Staphylococcus epidermidis ATCC
Agar media for seed and base layer
- Glucose 1.0 g
- Peptone 6.0 g
- Meat extract 1.5 g
- Yeast extract 3.0 g
- Sodium chloride 10.0 g
- Agar 15.0 g
- Water 1000 mL
Mix all the ingredients, and sterilize. Adjust the pH of the solution so that it will be 7.8 to 8.0 after sterilization.
Agar medium for transferring test organisms.
Use the medium Agar media for seed and base layer in Medium for other organisms under Agar media for transferring test organisms.
Weigh accurately an amount of Gentamicin Sulfate Reference Standard, equivalent to about 25 mg (potency), dissolve in 0.1 mol/L phosphate buffer solution (pH 8.0) to make exactly 25 mL, and use this solution as the standard stock solution. Keep the standard stock solution at 15°C or lower, and use within 30 days. Take exactly a suitable amount of the standard stock solution before use, add 0.1 mol/L phosphate buffer solution (pH 8.0) to make solutions so that each mL contains 4 mg (potency) and 1 mg (potency), and use these solutions as the high concentration standard solution and the low concentration standard solution, respectively.
Weigh accurately an amount of Gentamicin Sulfate, equivalent to about 25 mg (potency), and dissolve in 0.1 mol/L phosphate buffer solution (pH 8.0) to make exactly 25 mL. Take exactly a suitable amount of this solution, add 0.1 mol/L phosphate buffer solution (pH 8.0) to make solutions so that each mL contains 4 mg (potency) and 1 mg (potency), and use these solutions as the high concentration sample solution and the low concentration sample solution, respectively.
It should be stored in tight and air-free containers and should be keep away from moisture area.
Japan Pharmacopia (JP XVII) Official monographs Page 983.
United State Pharmacopia (USP 41) Page 938.