Polymyxin
Acinetobacter baumannii and Pseudomonas aeruginosa, Klebsiella spp., Enterobacter spp., Escherichia coli, Salmonella spp., Shigella spp., Citrobacter spp., Yersinia pseudotuberculosis, and Haemophilus influenzae
Colsitin disrupts bacterial cell membrane phospholipids
Peak:MIC and AUC:MIC ration correlate best with efficacy
Cmax: 18mg//L; Tmax: 2 hours; Half-life: 2-3 hours
Kidneys: Nephrotoxicity
Other: Neurotoxicity, drug fever
Skin: Pruritis, dermatoses
GI: gastrointestinal upset
Hematologic: leucopenia, granulocytopenia
FDA Warning: Colistin in Nebulizer Solution
Dosing in adults: 2.5-5mg/kg/day divided q6-12h
Dosing in pediatrics: 2.5-5mg/kg/day divided q6-12h
Renal failure: CrCl > 50mL/min: Standard dosing
CrCl 10-50mL/min: 50% of normal dose
CrCl < 10 mL/min: 25% of the normal dose
Hepatic failure: No dosing changes recommended at this time.
CVVH (Continuous venovenous hemofiltration): 2.5mg/kg IV q48h
CVVHD (Continuous venovenous hemodialysis): 2.5mg/kg IV q48h*
CVVHDF (Continuous venovenous hemodiafiltration) 2.5mg/kg IV q48h*
*A recent pharmacokinetic study suggests conventional dosing recommendations in CVVHD and CVVHDF are not appropriate in the critically ill and higher doses of 2-3 mg/kg IV q12h may be more appropriate. (Li J, et al. Antimicrob Agents Chemother 2005;49:4814-4815)
Note: CVVH is mainly for fluid removal alone. Many institutions will employ more CVVHD or CVVHDF which combine dialysis with fluid removal.
Precautions: Renal impairment
Non-depolarizing neuromuscular blockers: may lead to additive neuromuscular blockade
Category C: Risk unknown. Human studies inadequate
Therapeutic: Culture and sensitivities, serum levels, signs and symptoms of infection, white blood cell count
Toxic: Nephrotoxicity (Serum creatinine, BUN)
Colymycin (various generic manufacturers worldwide)