Polymyxin B / ColistinGroup of peptide antibiotics
Polymyxin B and colistin are related peptide antibiotics used against selected Gram-negative bacteria. Their importance in difficult infections comes with significant toxicity and formulation considerations.
Before comparing this entry. Two names share this source record. They require separate profiles before clinical comparison.
What is Polymyxin B / Colistin?
Polymyxin B and colistin are related antibiotics used in selected difficult Gram-negative infections. They are distinct agents; colistin may be supplied through the prodrug colistimethate sodium.
How it works
They interact with the bacterial outer membrane. Clinical value depends on the organism, its susceptibility and whether useful exposure is achieved at the infection site.
Effects studied
What does the evidence show?
Serious-infection clinical evidence and product-specific use
Targeting a bacterial membrane
These antibiotics interact with components of the outer membrane of Gram-negative bacteria. That mechanism can be useful against organisms resistant to other treatments. It does not mean they are appropriate for every resistant infection: susceptibility, infection site and alternative options still matter.
Keep the names and formulations separate
Polymyxin B and colistin belong to the same family but differ in their pharmacology. Colistin may be delivered as the prodrug colistimethate sodium. Confusing the active drug, prodrug or product units can have clinical consequences, so there is no simple substitution rule.
What clinical trials need to answer
Studies of severe infections may compare a polymyxin-based regimen with another strategy or test whether adding a second antibiotic improves outcomes. A result depends on the organism, the infection and the accompanying care. Laboratory susceptibility alone does not tell us that one regimen improves survival.
The cost of antibacterial activity
Systemic exposure can cause kidney injury and neurological toxicity. Treatment therefore requires dose adjustment, monitoring and specialist stewardship. Inhaled, topical and systemic use also require separate safety assessments. These antibiotics have a role in carefully selected infections, not in general antimicrobial or wellness use.
Safety & status
Systemic exposure can cause kidney injury and neurological toxicity. Active-drug versus prodrug units, formulation and route must remain explicit; these agents do not have a simple substitution rule.
Country and product status
Country-specific product availability and authorisation require a separate current check.
Frequently asked questions
Are polymyxin B and colistin interchangeable?
No. Their pharmacology and preparations differ, including colistin’s possible delivery as a prodrug.
Does a susceptible laboratory result guarantee success?
No. Infection site, drug exposure, patient condition and the overall regimen also influence outcome.
Sources
This entry was rewritten from our research archive. References below are reading leads unless a completed check is explicitly noted; a full independent evidence and regulatory review is still pending.
- Polymyxin B / Colistin · retained archive reference Archive research lead · Retained archive reference; not independently checked for this draft
- Polymyxin B / Colistin · retained archive reference Archive research lead · Retained archive reference; not independently checked for this draft
Research provenance
This name was discovered in the Superpower peptide index, archived 26 October 2026. Its ratings and reviewer attribution have not been adopted as our own. The archive informed this original editorial draft; independent source review is still pending.