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Polymyxin antibiotic

Colistimethate sodium

Brand names: Promixin, Colomycin, Colobreathe

Colistimethate sodium is the inactive prodrug formulation of colistin (polymyxin E), a polymyxin antibiotic reserved for serious infections caused by multidrug-resistant Gram-negative bacteria and given intravenously or by nebulisation.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

After hydrolysis to colistin, it binds the lipopolysaccharide of the Gram-negative outer membrane, disrupting membrane integrity and causing bactericidal cell death.

Prescribing in practice

  • Dose-related nephrotoxicity and neurotoxicity are the principal hazards and dosing must be adjusted in renal impairment, with avoidance of other nephrotoxins where possible.
  • Nebulised use can provoke bronchospasm, so an initial dose under supervision and pre-treatment bronchodilation may be needed.
  • Different products and labelling conventions vary, so prescribe and dispense with care to avoid units-based errors.

Monitoring

Monitor renal function regularly throughout treatment and observe for neurological symptoms such as paraesthesia or confusion.

Counselling the patient

  • Report numbness, tingling, dizziness or reduced urine output.
  • With the inhaled form, tell the team if you become wheezy or short of breath after a dose.

Evidence & guidelines

Use is supported by product information and specialist guidance for multidrug-resistant Gram-negative infection.

Reference: Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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