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Antimicrobial Agents and Chemotherapy, September 2005, p. 3676-3681, Vol. 49, No. 9
0066-4804/05/$08.00+0     doi:10.1128/AAC.49.9.3676-3681.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Absolute Bioavailability and Pharmacokinetics of Linezolid in Hospitalized Patients Given Enteral Feedings

University of Southern California, School of Pharmacy, Los Angeles, California,¹ Western University, College of Pharmacy, Pomona, California,² University of Oslo, School of Pharmacy, Oslo, Norway, and MDS Pharma Services, Hamburg, Germany,³ Huntington Hospital, Department of Pharmacy, Pasadena, California⁴

Received 8 December 2004/ Returned for modification 17 March 2005/ Accepted 23 June 2005

Linezolid is a new antimicrobial agent effective against drug-resistant gram-positive pathogens which are common causes of infections in hospitalized patients. Many such patients rely on the intravenous or enteral route for nutrition and drug administration. Therefore, the bioavailability of linezolid administered enterally in the presence of enteral feedings in hospitalized patients was examined. Eighteen subjects were assessed in a randomized single-dose crossover study; 12 received continuous enteral feedings, while 6 did not (controls). Both groups received linezolid 600 mg intravenously and orally (control) or enterally, with the alternate route of administration separated by a 24-h washout period. Pharmacokinetic parameters derived from noncompartmental and compartmental analysis incorporating linear and nonlinear elimination pathways were compared between groups: F, K_a, V_s, K₂₃, K₃₂, V_max, K_m, and K₂₀ (bioavailability, absorption rate constant, volume of central compartment normalized to body weight, intercompartmental rate constants, maximum velocity, Michaelis-Menten constant, and elimination rate constant, respectively). Pharmacokinetic (PK) data were available from 17 patients. The linezolid oral suspension was rapidly and completely absorbed by either the oral or enteral route of administration. Bioavailability was unaltered in the presence of enteral feedings. PK estimates remain similar regardless of the model applied. At the therapeutic dose used, only slight nonlinearity in elimination was observed. A linezolid oral suspension may be administered via the enteral route to hospitalized patients without compromise in its excellent bioavailability and rapid rate of absorption. Compartmental pharmacokinetic analysis offers a more flexible study application, since bioavailability (F) can be estimated directly with intermixed intravenous/oral doses without a need for a washout period.