Colistimethate
Colistimethate is a polymyxin antibiotic used as a last-resort treatment for serious multidrug-resistant gram-negative bacterial infections when conventional antibiotics are ineffective. It can be administered intravenously for systemic infections or via inhalation for chronic respiratory infections, particularly in cystic fibrosis patients.
A last-resort polymyxin antibiotic for treating serious multidrug-resistant gram-negative bacterial infections.
Key facts at a glance
- RxNorm
- 2708
- Generic
- Colistimethate
- Class
- pin-variant
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Treats serious gram-negative bacterial infections caused by multidrug-resistant organisms including Pseudomonas aeruginosa, Acinetobacter baumannii, and certain Enterobacteriaceae. Commonly used for cystic fibrosis patients with chronic respiratory infections and for ventilator-associated or hospital-acquired pneumonia when resistant organisms are involved.
As a cationic polypeptide antibiotic, colistimethate binds to the outer and cytoplasmic membranes of gram-negative bacteria. It displaces calcium and magnesium ions from the phospholipid components, disrupting membrane integrity and increasing permeability. This leads to leakage of cellular contents and bacterial cell death.
Carries significant risk of nephrotoxicity requiring regular monitoring of kidney function. Neurotoxic effects including paresthesias, muscle weakness, and rarely respiratory paralysis may occur. Use is typically reserved for infections where other treatment options have failed due to these safety concerns. Dosing must be carefully adjusted for renal function.
Official drug label
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This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy