Side-by-Side Comparison · 2026

Colistin vs Polymyxin B

Colistin vs Polymyxin B — mechanism, half-life, dosing, and research status compared. Which is right for your protocol?

Colistin
Antimicrobial Peptide

Colistin (polymyxin E) is a cyclic lipopeptide antibiotic structurally related to polymyxin B, differing in the fatty acid chain and one amino acid residue. Like polymyxin B, colistin targets LPS and disrupts outer membranes of Gram-negative bacteria....

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Polymyxin B
Antimicrobial Peptide

Polymyxin B is a cyclic lipopeptide antibiotic from Bacillus polymyxa that was approved in the 1960s and fell out of favor due to nephrotoxicity, but has experienced a major clinical resurgence as a last-resort treatment for carbapenem-resistant Gram-negative infections (Acinetob...

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Key Parameters
Parameter Colistin Polymyxin B
Category Antimicrobial Peptide Antimicrobial Peptide
Research FDA Approved FDA Approved
Half-Life Colistimethate (prodrug): 2-3 hours; active colistin: 14 hours 6-8 hours
Typical Dose 2.5-5 mg/kg/day CBA IV 15,000-25,000 units/kg/day IV
Frequency Every 8-12 hours Every 12 hours IV
Route IV (colistimethate) / Inhaled / Topical IV / IM / Topical / Intrathecal
FDA Status Approved (systemic Gram-negative infections) Approved (systemic Gram-negative infections)

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Frequently Asked Questions
What is the difference between Colistin and Polymyxin B?
Colistin: Colistin (polymyxin E) is a cyclic lipopeptide antibiotic structurally related to polymyxin B, differing in the fatty acid chain and one amino acid residue. Like polymyxin B, colistin targets LPS and ... Polymyxin B: Polymyxin B is a cyclic lipopeptide antibiotic from Bacillus polymyxa that was approved in the 1960s and fell out of favor due to nephrotoxicity, but has experienced a major clinical resurgence as a l...
Which has a longer half-life, Colistin or Polymyxin B?
Colistin half-life: Colistimethate (prodrug): 2-3 hours; active colistin: 14 hours. Polymyxin B half-life: 6-8 hours.
Can you stack Colistin and Polymyxin B?
Colistin and Polymyxin B are in the same category and used together in research protocols. Always consult relevant literature and follow appropriate guidelines.

For research use only. Not medical advice. ASCEND does not conduct or endorse any specific research protocol. Always consult relevant scientific literature and regulatory guidelines.