(gram'' i sye' din).
» Gramicidin is an antibacterial substance produced by the growth of Bacillus brevis Dubos (Fam. Bacillaceae). It may be obtained from tyrothricin. It has a potency of not less than 900 µg of gramicidin per mg, calculated on the dried basis.
Packaging and storage Preserve in tight containers.
USP Reference standards 11
USP Gramicidin RS
Identification, Ultraviolet Absorption 197U
Solution: 50 µg per mL.
Melting temperature, Class Ia 741: not lower than 229, determined after drying.
Crystallinity 695: meets the requirements.
Loss on drying 731 Dry about 100 mg in a capillary-stoppered bottle in vacuum at 60 for 3 hours: it loses not more than 3.0% of its weight.
Residue on ignition 281: not more than 1.0%, the charred residue being moistened with 2 mL of nitric acid and 5 drops of sulfuric acid.
Assay Proceed with Gramicidin as directed under AntibioticsMicrobial Assays 81.
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