Colistimethate Sodium Guide: Uses, Dosage, Side Effects
Comprehensive guide to colistimethate sodium (Colobreathe, Colomycin, Promixin) uses, dosage, side effects, and patient advice for treating serious infections.
Colistimethate sodium is a potent antibiotic primarily used to combat serious infections caused by gram-negative bacteria, particularly Pseudomonas aeruginosa. It is available under brand names such as Colobreathe, Colomycin, and Promixin, and is especially valuable for patients with cystic fibrosis (CF) experiencing chronic pulmonary infections. This medication works by disrupting the bacterial cell membrane, leading to bactericidal activity against aerobic gram-negative microorganisms. While systemic use carries risks of nephrotoxicity and neurotoxicity, inhaled forms minimize these issues, making it a cornerstone therapy for CF-related lung infections.
About colistimethate sodium
Colistimethate sodium, a prodrug of colistin, is indicated for acute or chronic infections due to susceptible gram-negative bacilli, with particular efficacy against Pseudomonas aeruginosa. It has been employed for decades in treating pulmonary infections in CF patients, where P. aeruginosa dominates from early childhood, often leading to multiresistant strains. Unlike colistin sulfate, colistimethate is less toxic when administered systemically but converts to active colistin in vivo. Inhaled formulations like nebulized solutions or dry powders (e.g., Colobreathe) deliver high concentrations directly to the lungs, reducing systemic exposure.
Historically, colistimethate gained prominence for multidrug-resistant infections, including Acinetobacter baumannii and carbapenem-resistant strains, though resistance has emerged. The FDA approves it for infections from Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. In CF, early aggressive inhalation therapy has shown benefits in delaying chronic infection and preserving lung function.
Before antibiotics: Colistin, discovered in 1947, fell out of favor due to toxicity but resurged with antibiotic resistance crises. Modern use emphasizes inhalation for CF, with intravenous or intrathecal routes for severe cases like meningitis.
Before taking colistimethate sodium
Some medicines are not suitable for people with certain conditions
Colistimethate sodium requires caution in patients with kidney impairment, as it can exacerbate nephrotoxicity. It is contraindicated in those with known hypersensitivity to colistin or polymyxins. Use in myasthenia gravis or other neuromuscular disorders is risky due to potential respiratory muscle weakness. Pregnant or breastfeeding individuals should consult providers, as safety data is limited.
Consult your doctor if you are pregnant or breastfeeding
- Pregnancy: Limited human data; animal studies suggest potential fetal harm. Use only if benefits outweigh risks.
- Breastfeeding: Colistin appears in breast milk in low amounts; monitor infant for GI effects.
Important information that your doctor needs to know
- Allergies to polymyxins or sulfites (in some formulations).
- Kidney function tests (e.g., creatinine clearance).
- Concurrent medications: Avoid nephrotoxic drugs like aminoglycosides, vancomycin.
- CF status or history of pulmonary exacerbations.
How to take colistimethate sodium
Administration varies by route: inhalation (preferred for CF pulmonary infections), intravenous (IV), or intramuscular (IM). Always follow prescribed dosing; do not self-adjust.
Dosage
Inhaled (CF pulmonary infections): UK guidelines recommend 1–2 million units (80–160 mg) nebulized twice daily for adults. Colobreathe (dry powder): 1–2 million IU twice daily. Pediatric dosing is weight-based, often 40 mg twice daily via nebulizer.
IV/IM: Adults: 2.5–5 mg/kg/day divided every 8–12 hours, adjusted for renal function. Pediatrics: Similar, with monitoring.
| Route | Adult Dose | Pediatric Dose | Frequency |
|---|---|---|---|
| Inhaled | 1–2 million IU | Weight-based (e.g., 40 mg) | Twice daily |
| IV/IM | 2.5–5 mg/kg/day | 2.5–5 mg/kg/day | Every 8–12 hours |
How to use the inhaler/nebuliser
- Wash hands thoroughly.
- For nebulizer: Reconstitute powder with sterile water; use specific devices like Pari LC Plus.
- Breathe normally until mist is gone (10–15 minutes); cough to clear airways.
- Clean equipment after each use to prevent contamination.
- For Colobreathe DPI: Inhale deeply and forcefully while capsule spins.
Avoid eating/drinking 1 hour before/after to minimize bronchospasm risk.
Getting the most from your treatment
- Complete full course to prevent resistance, critical in CF where multiresistant P. aeruginosa develops.
- Combine with physiotherapy and mucolytics for better lung clearance.
- Monitor sputum cultures; rotate with tobramycin or aztreonam if needed, though colistin remains effective.
- Hydrate well for IV use to protect kidneys.
- Report worsening symptoms immediately.
If you forget a dose
Take as soon as remembered unless near next dose; do not double up. For inhaled CF therapy, consistency is key for sustained lung function benefits.
If you take too much colistimethate sodium
Overdose risks acute kidney injury, apnea, or neuromuscular blockade. Seek emergency care; supportive treatment includes hemodialysis.
Side-effects
Inhaled forms are well-tolerated, but systemic use poses higher risks.
Common side effects (inhaled)
- Bronchospasm, sore throat, cough.
- Manage with bronchodilators pre-dose.
Serious side effects
| System | Symptoms | Action |
|---|---|---|
| Renal | Reduced urine, swelling | Stop drug, check creatinine |
| Neuro | Weakness, paresthesia, apnea | Emergency support |
| Resp | Severe bronchospasm | Bronchodilators, discontinue |
| Allergic | Rash, anaphylaxis | Epinephrine, stop |
Studies show inhaled colistimethate superior to placebo in CF, with low resistance rates. Monitor electrolytes, renal function weekly on IV.
Further information
Store powder at room temperature; reconstituted solutions refrigerated up to 14 days. Patient support: CF trusts provide nebulizer training. Alternatives include tobramycin inhalation, though meta-analyses favor tobramycin slightly for FEV1 improvement.
Date reviewed: March 2024
Next review due: March 2027 (adapted from sources up to 2025).
Disclaimer
This information mirrors professional advice but substitutes no medical consultation. Verify with healthcare providers.
Frequently Asked Questions (FAQs)
Q: What infections does colistimethate sodium treat?
A: Primarily gram-negative infections like Pseudomonas aeruginosa in CF lungs, plus E. coli, Klebsiella, and multidrug-resistant cases.
Q: Is inhaled colistimethate safe for long-term CF use?
A: Yes, studies confirm efficacy and safety over months, reducing exacerbations with minimal systemic toxicity.
Q: How does it compare to tobramycin?
A: Both effective; tobramycin may edge in lung function, but colistin useful for resistance patterns.
Q: Can it cause kidney damage via inhalation?
A: Rare; systemic absorption is low, but monitor in renal impairment.
Q: What’s the role in non-CF infections?
A: IV for severe cases like ventilator pneumonia or meningitis.
References
- Colistin – Wikipedia — Wikipedia contributors. 2024-01-01. https://en.wikipedia.org/wiki/Colistin
- Colistimethate sodium for the treatment of chronic pulmonary infections in cystic fibrosis — PMC. 2014-10-01. https://pmc.ncbi.nlm.nih.gov/articles/PMC4178503/
- Colistimethate: Uses, Interactions, Mechanism of Action — DrugBank. 2025-01-01. https://go.drugbank.com/drugs/DB01111
- Coly-Mycin M Parenteral Label — FDA. 2025-01-01. https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/050108s041lbl.pdf
- Colistimethate (colistin) — Johns Hopkins ABX Guide. 2024-01-01. https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540140/1/Colistimethate__colistin_
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