Colistimethate

General

• Type: Antibiotic
• Dosage Forms: IV
• Common Trade Names:

Adult Dosing

• 2.5-5 mg/kg/day divided q6-12hr IV/IM; not to exceed 5 mg/kg/day

Pediatric Dosing

• <12yo: safety/efficacy not established

Special Populations

• Pregnancy Rating: C
• Lactation: Unknown, use caution
• Renal Dosing
  • CrCl 50-79 mL/min: 2.5-3.8 mg/kg/day IV/IM divided q12hr
  • CrCl 30-49 mL/min: 2.5 mg/kg/day IV/IM qDay or divided q12hr
  • CrCl 10-29 mL/min: 1.5 mg/kg IV/IM q36hr
• Hepatic Dosing: Not established

Contraindications

• Allergy to class/drug

Adverse Reactions

Serious

• Anaphylaxis
• Acute respiratory failure, particularly in myasthenia gravis or recent use of NMJ blockade
• Nephrotoxicity
• Neurotoxicity, seizures
• C. diff pseudomembranous colitis

Common

• Dizziness
• Paresthesias
• Dysarthria

Pharmacology

• Half-life: 2-3h
• Metabolism:
• Excretion: Urine
• Mechanism of Action: "Cationic detergent that damages bacterial cytoplasmic membrane, causing cell death"

Antibiotic Sensitivities

Group	Organism	Sensitivity
Gram Positive	Strep. Group A, B, C, G	R
	Strep. Pneumoniae	R
	Viridans strep	X1
	Strep. anginosus gp	X1
	Enterococcus faecalis	R
	Enterococcus faecium	R
	MSSA	R
	MRSA	R
	CA-MRSA	R
	Staph. Epidermidis	R
	C. jeikeium	R
	L. monocytogenes	R
Gram Negatives	N. gonorrhoeae	R
	N. meningitidis	R
	Moraxella catarrhalis	X1
	H. influenzae	X1
	E. coli	S
	Klebsiella sp	S
	E. coli/Klebsiella ESBL+	S
	E coli/Klebsiella KPC+	S
	Enterobacter sp, AmpC neg	S
	Enterobacter sp, AmpC pos	S
	Serratia sp	X1
	Serratia marcescens	R
	Salmonella sp	X1
	Shigella sp	X1
	Proteus mirabilis	X1
	Proteus vulgaris	R
	Providencia sp.	X1
	Morganella sp.	X1
	Citrobacter freundii	X1
	Citrobacter diversus	X1
	Citrobacter sp.	X1
	Aeromonas sp	X1
	Acinetobacter sp.	S
	Pseudomonas aeruginosa	S
	Burkholderia cepacia	R
	Stenotrophomonas maltophilia	I
	Yersinia enterocolitica	X1
	Francisella tularensis	X1
	Brucella sp.	X1
	Legionella sp.	X1
	Pasteurella multocida	X1
	Haemophilus ducreyi	X1
	Vibrio vulnificus	X1
Misc	Chlamydophila sp	X1
	Mycoplasm pneumoniae	X1
	Rickettsia sp	X1
	Mycobacterium avium	X1
Anaerobes	Actinomyces	X1
	Bacteroides fragilis	X1
	Prevotella melaninogenica	X1
	Clostridium difficile	X1
	Clostridium (not difficile)	X1
	Fusobacterium necrophorum	X1
	Peptostreptococcus sp.	X1

Key

• S susceptible/sensitive (usually)
• I intermediate (variably susceptible/resistant)
• R resistant (or not effective clinically)
• S+ synergistic with cell wall antibiotics
• U sensitive for UTI only (non systemic infection)
• X1 no data
• X2 active in vitro, but not used clinically
• X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
• X4 active in vitro, but not clinically effective for strep pneumonia