TABLE 5.

Pharmacokinetic parameter estimates for IVA in plasma, ELF, and lungs from infected and non-infected mice^a

Sample	Mouse group	Pharmacokinetic parametersb
		tmax (h)	Cmax (ng/mL)	tlast (h)	Clast (h)	AUClast (h·ng/mL)	AUCinf (h·ng/mL)	t1/2 (h)	MRT (h)
Plasma	Non-infected	1	2,345	24	4.0	7,482	7,498	2.9	2.9
	Infected	1	968	24	8.6	9,111	9,152	3.3	4.7
ELF	Non-infected	1	537	6	116.7	1,932	2,307	2.2	2.1
	Infected	1	981	6	194.3	2,590	3,236	2.3	2.2
Lung	Non-infected	1	249	6	68.2	946	nd	nd	2.2
	Infected	1	364	24	4.4	4,010	4,033	3.7	5.2

^aC57BL/6NCrlBR male mice (8 to 10 weeks of age) were infected with 1 × 10⁶ CFU of P. aeruginosa PAO1 by intratracheal administration. A non-infected control group was also tested in parallel. Thirty minutes after infection, the mice were treated with 3 mg/kg IVA in 10% PEG 400, 10% Tween 80, and 80% saline by intraperitoneal administration. Mice were sacrificed at 10 min and 1, 2, 6, and 24 h after IVA administration. Blood was collected and processed to obtain plasma. BALF was collected and centrifuged, and the supernatant was used to quantify the IVA concentration. Lungs were excised, homogenized, and centrifuged, and the supernatants were used to quantify IVA concentrations. Plasma, lung homogenate, and BALF were added to a Phree phospholipid removal plate (Phenomenex) with acetonitrile and 0.1% formic acid in order to eliminate phospholipids, decreasing the matrix effect. Eluates were analyzed by UPLC-MS/MS with a linear gradient in multiple reaction monitoring positive mode. Calibration ranges were 0.5 to 750 ng/mL in plasma and BALF and 4 to 1,000 ng/g in the lung homogenate. Concentrations of IVA in ELF were determined using the ratio of the urea concentration in plasma to that in BALF: concentration in ELF = (drug concentration in BALF) × (urea in plasma)/(urea in BALF). The data are the geometric means of values from 3 to 4 mice.

^bt_max, time of maximum concentration; C_max, maximum concentration; t_last, time of last quantifiable concentration; C_last, last quantifiable concentration; AUC_last, AUC to the last quantifiable concentration level; AUC_inf, AUC to infinity; t_1/2, half-life; MRT, mean residence time; nd, not determined.