TABLE 1.

Colistin concentrations in ELF and in plasma (unbound) after intratracheal or i.v. administration^a

Time postadministration (h)	i.v.			NEB
	CELF (μg/ml)	C(plasma, unbound) (μg/ml)	CELF/C(plasma, unbound) ratio	CELF (μg/ml)	C(plasma, unbound) (μg/ml)	CELF/C(plasma, unbound) ratio
0.5	<LOQ	0.31 ± 0.05	NA	153 ± 49	0.20 ± 0.05†	825 ± 345
2	<LOQ	0.05 ± 0.01	NA	112 ± 29	0.06 ± 0.02	1,794 ± 572
4	ND	<LOQ	NA	20 ± 14	0.012 ± 0.004	1,770 ± 611

^aColistin concentrations in ELF and in plasma (unbound) at 0.5, 2, and 4 h after intratracheal administration of the nebulized form (NEB) or i.v. administration (dose, 0.35 mg/kg). Values are means ± standard deviations. C_{(plasma, unbound)} was estimated by multiplying experimental total concentrations by 0.45 (corresponding to the colistin unbound fraction in plasma) (30). †, significantly different from the unbound drug plasma concentration after i.v. administration; LOQ, limit of quantification; ND, not done; NA, not available.