Polymixin B 500

Last-resort antibiotic for multidrug-resistant gram-negative infections; low-dose IV in horses for endotoxin binding; intrauterine infusion for equine endometritis. Polypeptide antibiotic (polymyxin B sulfate). Mechanism: cationic amphipathic cyclic lipopeptide that disrupts gram-negative outer membrane lipopolysaccharide → membrane permeabilization → bactericidal. Sub-antimicrobial doses bind and neutralize circulating endotoxin (LPS) in horses. Key information Polymyxin B — see polymyxin B entry.

Topical/otic: apply as directed. Verify TM integrity before otic use. IV (sub-antimicrobial, horses): dilute; infuse slowly over 1–2 hrs. Store at room temperature; protect from light. If a dose is missed This medication is administered by a veterinarian or veterinary staff in a clinical setting. Missed doses are managed by your veterinary team — contact your veterinarian to reschedule.

Nephrotoxicity and neurotoxicity (dose-dependent; systemic use — rare in veterinary sub-antimicrobial/endotoxin doses). Topical otic: ototoxicity if TM perforated. Pain at injection site. Histamine release (IV rapid infusion). Use with caution in renal impairment.

For animals Ototoxic with ruptured tympanic membrane — verify integrity before otic use. Systemic: nephrotoxic and neurotoxic at antimicrobial doses — not typically used systemically in horses (sub-antimicrobial endotoxin-binding dose is the common use). Monitor renal function, hydration status, and urine output. if used systemically. For people handling this medication Wear gloves when handling. Wash hands thoroughly with soap and water after handling. Polypeptide antibiotic — avoid skin and eye contact with injectable form. Otic use: avoid ear exposure. Avoid contact with eyes; if contact occurs, flush with water for 15 minutes and seek medical attention.

Contact your veterinarian immediately. Polymyxin overdose causes kidney damage and neuromuscular effects.