• Olanrewaju O Okusanya, Sujata M Bhavnani, Jeffrey P Hammel, Alan Forrest, Catharine C Bulik, Paul G Ambrose, and Renu Gupta.
• Institute for Clinical Pharmacodynamics, Latham, New York, USA.
• Antimicrob. Agents Chemother. 2014 Sep 1; 58 (9): 5005-15.

AbstractThe pharmacokinetic-pharmacodynamic (PK-PD) relationships between serum exposure measures of liposomal amikacin for inhalation (LAI) and the change in pulmonary function test (PFT) measures and number of CFU from baseline were evaluated in cystic fibrosis (CF) patients chronically infected with Pseudomonas aeruginosa. A dose of 70, 140, 280, or 560 mg of LAI or placebo was administered to CF patients once daily for 28 days. PFTs and sputum samples for microbiology were assessed on days 7, 14, 21, 28, 35 (for log10 CFU), and 56 (for PFTs). Serum, urine, and sputum samples were collected for PK evaluation. The relationships between efficacy endpoints (relative change in forced expiratory volume in 1 s [FEV1 {expressed in liters}] and FEV1% predicted and the absolute change in log10 CFU of P. aeruginosa from baseline) and exposure measures (dose, day 1 area under the curve [AUC], dose/MIC ratio, and day 1 AUC/MIC ratio) and baseline MIC value were assessed. The serum and urine PK data were best fit by a 3-compartment model (lung, serum, and urine) with linear clearance and interoccasional variation on total and renal clearance. Significant univariable relationships between dose or day 1 AUC and the relative change in PFT measures (P≤0.017) or the absolute change in log10 CFU from baseline (P≤0.037) on the study days were identified. Repeated-measures mixed-effects models, which showed dose- and AUC-related improvements for each efficacy endpoint (P≤0.041), predicted the observed data well. The increases in the relative change in FEV1 and FEV1% predicted of 11% and 9.9%, respectively, and a 1.23-log10 CFU reduction per 560 mg of LAI estimated on day 7 were comparable to the observed increases of 10.7% and 10.3%, respectively, and a 1.24-log10 CFU reduction on the same day. The model-estimated PFT effects were predicted to be sustained to day 28. An additional 0.451-log10 CFU reduction (P=0.022) was estimated on day 14 relative to day 7, with a persistence of effect predicted to day 35.Copyright © 2014, American Society for Microbiology. All Rights Reserved.

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