- Antibacterial activity
- Rapidly bactericidal if MBC is reached.
- Gram negative only.
- Aerobic activity (An equivocal point. You will find different opinions in different places. I'll advocate for what I'm sure of - aerobic)
- Bacterial resistance
- Low clinical concern. (Low frequency of resistance and systemic use is rare.)
- Concentrations and doses
- No absorption when used topically.
- Almost never given systemically as antibacterial.
- Toxicity Profile
- Life threatening adverse effects are common when administered for systemic effect.
Beneficial actions and effects
- Disrupt bacterial cell membrane by interacting with phospholipids
- Spectrum almost exclusively gram negative.
Resistance (by bacteria)
- Plasmid mediated change in bacterial cell membrane structure.
- Binds and disrupts cell membranes of all kinds
- Neurotoxic and nephrotoxic
- Almost too toxic to use. Rarely used as a last resort for resistant gram negative infections
- Systemic use is very rare, pharmacokinetics are virtually unknown.
- No absorption from topical use
- Used almost exclusively as a topical agent due to systemic toxicity
- Use for "endotoxemia" is questionable
- Polymyxin B does, in fact, bind endotoxin
- effective dose is in question
- Clinical evidence (outcomes) lacking