Polymyxins Polymyxin

Polymyxines Polymyxines are a gronp of related polypeptide antibiotics that are produced by sporo-forming soil bacteria Bacillus polymyxa and B. circulans, and they differ in amino acid content. Five different polymyxines have been identified—polymyxines A, B, C, D, and E, which differ in the amino acid content and are differentiated by additional letter notations and names— polymyxine B (aerosporin) and polymyxine E (colistin). It is known that in the process of development, some strains of B. polymyxa only form polymyxines A and C, and others synthesize polymyxines B and D. Polymyxine M was later isolated, a snlfomethyl derivative of polymyxine E. 

Polymyxins. Polymyxin B [1404-26-8] and polymyxin E [1066-17-7] (colistin) are the only medically important antibacterials from a group of some thirty closely related cyclic decapeptide antibiotics in the polymyxin family, some of which are given in Table 2. Most family members contain a seven amino acid ring attached to a three amino acid tail, to which is attached a fatty acyl group. The octapeptins have a tail containing a single amino acid. Each antibiotic contains several L-a-y-diaminobutyric acid [1758-80-1], C4H10N2O2, (Dab) residues, L-threonine [72-19-5], at least one D-amino acid, and one of a very limited list of fatty acids. 

Polymyxins Polymyxin A 2,720 thiazole- 4-carboxylic acid, Thr thiazole-4-carboxylic acid ... 

Polymyxins Polymyxin B 4.3-6 h 30,000 units/kg/d Nephrotoxiciiy and noncompetitive neuromuscular blockade. 

The neuromuseular bloeking properties of the polymyxins (polymyxin B, eolistin, eolistimethate sodium) involve a number of mechanisms, which may explain the difficulty in reversing the blockade. ... 

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