สารบัญ

Neomycin sulfate                         1405-10-3

Category Antibacterial.

      Neomycin Sulfate is a mixture of the sulfates of substances produced by the growth of certain selected strains of Streptomyces fradiae. It contains not less than 600 μg of neomycin per mg, calculated on the dried basis.

Description White or yellowish white powder; hygroscopic.

Solubility Freely soluble in water; very slightly soluble in ethanol; insoluble in acetone, in chloroform and in ether.

Stability It is hygroscopic, but it is relatively stable in the dry state. In aqueous solutions, it may become darkened when stored at room temperature, but its antibacterial potency is still retained for several months.

Therefore, its aqueous solutions should be refrigerated.

Contra-indication It is contra-indicated in patients with a history of hypersensitivity reactions to any member of aminoglycosides.

Warning See under Gentamicin Sulfate, p. 111.

Precaution Because of the potential risk of the increased absorption of neomycin sulfate from the inflamed or ulcerated gastro-intestinal tract, it should be used with caution in such conditions.

      See also under Gentamicin Sulfate, p. 111. 

Additional information

      1. Because of its potential toxicity, the parenteral use of neomycin is not recommended for any indication.

      2. Local application should be limited to the treatment of neomycin-sensitive staphylococcal infections and prolonged topical use should be avoided as it leads to skin sensitization.

Packaging and storage Neomycin Sulfate shall be kept in tightly closed containers, protected from light, and stored at a temperature not exceeding 30º. 

Labelling The label on the container states (1) the number of μg of activity per mg; (2) storage condition; (3) sterile or non-sterile grade.

Identification

      A. Carry out the test as described in the “Thin-layer Chromatography” (Appendix 3.1), using silica gel G as the coating substance and as the mobile phase a mixture of 1 volume of chloroform, 3 volumes of methanol and 2 volumes of strong ammonia solution. Apply separately to the plate, 1 μl of each of two solutions containing (A) 1 mg per ml of the test substance and (B) 1 mg per ml of Neomycin Sulfate RS and at a third point, apply 1 μl of a mixture of equal volumes of solutions (A) and (B). After removal of the plate, allow it to dry in air, spray with a 1 per cent w/v solution of ninhydrin in 1-butanol, and heat at 105º for 2 minutes: the principal red spot in the chromatogram obtained from solution (A) corresponds with that in the chromatogram obtained from solution (B) and the principal red spot in the third chromatogram appears as a single compact spot.

      B. Dissolve 10 mg in 5 ml of water, add 2 drops of pyridine and 2 ml of a 0.1 per cent w/v solution of ninhydrin and heat on a water-bath at temperature between 65º and 70º for 10 minutes: a deep violet colour is produced.

      C. It yields the reactions characteristic of sulfates (Appendix 5.1).

pH 5.0 to 7.5, in a 1.0 per cent w/v solution (Appendix 4.11).

Specific rotation +53.5º to +59.0º, calculated on the dried basis, determined in a 10.0 per cent w/v solution (Appendix 4.8).

Loss on drying Not more than 8.0 per cent w/w after drying at 60º at a pressure not exceeding 0.7 kPa (about 5 Torr) for 3 hours (Appendix 4.15).

Sulfated ash Not more than 1.0 per cent w/w (Appendix 5.3).

Assay Carry out the microbiological assay of Neomycin Sulfate according to the “Microbiological Assay of Antibiotics” (Appendix 6.10).