Approved & therapeutic
Colistimethate sodium
Coly-Mycin M, Colistin
Colistimethate sodium is the inactive prodrug of colistin, a polymyxin polypeptide antibiotic from the 1950s that returned to use as a last-line agent against multidrug-resistant Gram-negative organisms.
Also known as: Coly-Mycin M, colistin, colistin methanesulfonate, polymyxin E
- Status
- Colistimethate sodium is approved by the U.S. FDA and has official prescribing information.
- Evidence
- Approved labeling. Official prescribing information exists, based on clinical trials in people.
- Half-life
- Approximately 2 to 3 hours for formed colistin, prolonged in renal impairment.
- How it's taken
- Intravenous or intramuscular injection; also nebulised for airway infection
- Mechanism
- Immune modulation
How Colistimethate sodium works
Colistin is a cationic cyclic polypeptide with a fatty acyl tail. It binds the lipid A component of lipopolysaccharide in the Gram-negative outer membrane, displacing the divalent cations that stabilise it, which permeabilises the membrane and kills the cell. Colistimethate itself is inactive and must hydrolyse in vivo to colistin.
What research has looked at
- Retains activity against carbapenem-resistant Acinetobacter, Pseudomonas aeruginosa and Enterobacterales, where few options remain.
- The membrane target means cross-resistance with other antibiotic classes is uncommon.
- Inhaled formulations are used for chronic Pseudomonas suppression in cystic fibrosis and bronchiectasis.
Evidence level: Approved labeling. Official prescribing information exists, based on clinical trials in people. These are areas studied or reported, not promised effects.
Reported side effects and risks
- Nephrotoxicity is common and dose-limiting; it was the reason the drug fell out of use once safer agents appeared, and it remains the principal constraint.
- Neurotoxicity including paraesthesias, dizziness and, rarely, neuromuscular blockade with respiratory arrest — particularly with concurrent neuromuscular blocking agents.
- Dosing is genuinely confusing and has caused real harm: colistin base activity, colistimethate and international units are three different units used interchangeably in the literature.
- The prodrug converts slowly and incompletely, so effective concentrations are reached later than expected — a loading dose is generally needed.
- Inhaled colistimethate can cause bronchospasm, and there have been deaths from administering pre-mixed solutions in which the prodrug had already hydrolysed.
Sources
- FDA approved-drug listing for colistimethate · U.S. Food & Drug Administration
- DailyMed prescribing information for colistimethate · NIH · DailyMed
- PubMed research on colistin colistimethate dosing nephrotoxicity · NIH · National Library of Medicine
- DrugBank record for colistimethate · DrugBank
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Related compounds
Colistimethate sodium FAQ
What is Colistimethate sodium?
Colistimethate sodium is the inactive prodrug of colistin, a polymyxin polypeptide antibiotic from the 1950s that returned to use as a last-line agent against multidrug-resistant Gram-negative organisms.
How does Colistimethate sodium work?
Colistin is a cationic cyclic polypeptide with a fatty acyl tail. It binds the lipid A component of lipopolysaccharide in the Gram-negative outer membrane, displacing the divalent cations that stabilise it, which permeabilises the membrane and kills the cell. Colistimethate itself is inactive and must hydrolyse in vivo to colistin.
Is Colistimethate sodium FDA approved?
Yes. Colistimethate sodium is approved by the U.S. FDA and has official prescribing information. Evidence level: approved labeling. Official prescribing information exists, based on clinical trials in people.
What is the half-life of Colistimethate sodium?
Reported half-life: Approximately 2 to 3 hours for formed colistin, prolonged in renal impairment.
How is Colistimethate sodium taken?
Intravenous or intramuscular injection; also nebulised for airway infection.
What side effects have been reported with Colistimethate sodium?
Reported in the sources: Nephrotoxicity is common and dose-limiting; it was the reason the drug fell out of use once safer agents appeared, and it remains the principal constraint; Neurotoxicity including paraesthesias, dizziness and, rarely, neuromuscular blockade with respiratory arrest — particularly with concurrent neuromuscular blocking agents; Dosing is genuinely confusing and has caused real harm: colistin base activity, colistimethate and international units are three different units used interchangeably in the literature; The prodrug converts slowly and incompletely, so effective concentrations are reached later than expected — a loading dose is generally needed; Inhaled colistimethate can cause bronchospasm, and there have been deaths from administering pre-mixed solutions in which the prodrug had already hydrolysed.
Educational summary compiled from the sources listed above. Not medical advice. Peptide Vault does not sell, source or recommend any compound. Talk to a qualified clinician before starting or changing anything.