INDICATIONS

• Treatment of Endotoxemia in Horses: This is the most common and studied systemic (intravenous) use of polymyxin B in veterinary medicine. The typical dose is 6,000 units/kg administered intravenously as a slow infusion.
• Topical Preparations for Dogs and Cats: In companion animals, polymyxins are mainly found in combination with other antibiotics (like neomycin and bacitracin) in ointments and drops for localized infections.
  • Ocular (Eye) Infections: Used to treat infections of the eye, eyelid, and conjunctiva caused by susceptible bacteria, including Pseudomonas spp..
  • Otic (Ear) Infections: Used in ear drop formulations to combat bacterial ear infections.

ADMINISTRATION

• Intravenous (IV):
  • Typically diluted in saline (e.g., 1 liter) and infused over 30–60 minutes to treat endotoxemia.
  • Regional Limb Perfusion (IV-RLP): Used in horses to deliver high concentrations to a specific limb while minimizing systemic exposure.
• Intramuscular (IM): While possible, this route is not routinely recommended because it causes severe pain at the site of injection.
• Intrathecal/Intraventricular: Administered directly into the cerebrospinal fluid for severe infections like meningitis. 

• Reconstitution: The powder is typically dissolved in sterile water for injection, 0.9% sodium chloride (normal saline), or 5% dextrose.
• Dilution: For IV infusion, the dose is often further diluted in a large volume of carrier fluid (e.g., 300 to 500 mL or more) to reduce the risk of adverse reactions.
• Dosage Examples:
  • Horses: Often dosed at 6,000 U/kg IV every 8 to 12 hours for anti-endotoxic effects.