Colistin Sulfate
Also known as: Coly-Mycin M (colistimethate), Colomycin, Polymyxin E
CAS Number: 1264-72-8
Polymyxin antibiotic — last-resort for carbapenem-resistant gram-negative bacteria
Pharmacopeia Standards
Mechanism of Action
Cyclic polypeptide (lipopeptide) that disrupts gram-negative bacterial outer membrane integrity. Positively charged diaminobutyric acid residues displace Ca²⁺/Mg²⁺ stabilizing LPS, causing membrane permeability disruption, loss of osmotic control, and cell death. Bactericidal, concentration-dependent. Activity limited to gram-negative aerobes with lipopolysaccharide-containing outer membrane. Used as the inactive prodrug colistimethate sodium (CMS) for IV/inhalation.
Technical Specifications
| Generic / INN Name | Colistin Sulfate |
| CAS Registry Number | 1264-72-8 |
| Molecular Formula | Cyclic polypeptide mixture (Polymyxin E1 / E2) |
| Molecular Weight | ~1750 g/mol |
| Typical Purity | NLT 19,500 IU/mg (colistin sulfate) on dried basis |
| Storage Conditions | Store below 25°C, protect from light and moisture |
| Shelf Life | 24 months from date of manufacture |
| Category | Polymyxins |
Specifications are indicative and intended for sourcing reference only. Always confirm against the supplier's Certificate of Analysis and the applicable pharmacopeial monograph before issuing a purchase specification.
Typical Applications
Last-resort treatment for carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Pseudomonas aeruginosa (CRPA), carbapenem-resistant Enterobacteriaceae (CRE) — often in combination. Inhaled colistimethate for cystic fibrosis chronic Pseudomonas colonization. Oral colistin sulfate for gut decontamination. Animal growth promotion (now banned in many countries).
Manufacturers (1+)
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