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ALIMENTARY TRACT AND METABOLISM › ANTIDIARRHEALS, INTESTINAL ANTIINFLAMMATORY/ANTIINFECTIVE AGENTS › INTESTINAL ANTIINFECTIVES › Antibiotics
polymyxin B
A07AA05
Forms & Strengths
- Injection: 500,000 units per vial (as polymyxin B sulfate)
- Ophthalmic: 10,000 units/mL with neomycin and gramicidin
- Topical: 10,000 units/g with bacitracin
Adult Dosing
- Intravenous: 15,000 to 25,000 units/kg/day divided every 12 hours in patients with normal renal function
- Intrathecal: 50,000 units once daily for 3 to 4 days, then 50,000 units every other day for meningeal infections
- Ophthalmic: 1 to 2 drops into affected eye(s) 2 to 6 times daily
Pediatric Dosing
- Intravenous (infants and children): 15,000 to 40,000 units/kg/day divided every 12 hours
- Intrathecal (children >2 years): 50,000 units once daily for 3 to 4 days, then 50,000 units every other day
- Intrathecal (infants <2 years): 20,000 units once daily for 3 to 4 days, then 25,000 units every other day
Indications
- Treatment of acute infections caused by susceptible strains of Pseudomonas aeruginosa
- Infections caused by Escherichia coli, Haemophilus influenzae, Klebsiella pneumoniae, and Enterobacter aerogenes
- Meningitis caused by susceptible pathogens via intrathecal administration
- Topical treatment of superficial ocular and skin infections
Mechanism of Action
- Binds to phospholipids in the bacterial cytoplasmic membrane of susceptible Gram-negative bacteria
- Alters membrane permeability, leading to leakage of intracellular components and cell death
Contraindications
- Hypersensitivity to polymyxins
- Concurrent use of other neurotoxic or nephrotoxic drugs, particularly other polymyxins, aminoglycosides, or curariform muscle relaxants
Adverse Reactions
- Nephrotoxicity (albuminuria, cellular casts, azotemia)
- Neurotoxicity (facial flushing, dizziness, ataxia, drowsiness, peripheral neuropathy, apnea)
- Local irritation and thrombophlebitis at intravenous injection sites
- Neurotoxicity from intrathecal administration (meningeal irritation, fever, headache, paralysis)
Drug Interactions
- Increased risk of nephrotoxicity and neurotoxicity with aminoglycosides, cephaloridine, and other nephrotoxic agents
- Enhanced and prolonged neuromuscular blockade when administered concurrently with nondepolarizing muscle relaxants, anesthetics, and opioids
Curated Content: Needs Vetting Before Put to Clinical Use