Abstract | BACKGROUND:
Linezolid is an oxazolidinone antimicrobial with excellent oral bioavailability and tissue penetration and is active against multidrug-resistant skin/soft tissue pathogens. OBJECTIVE: To study the pharmacokinetics and antibacterial activity of linezolid against selective skin/soft tissue pathogens in obese patients. METHODS: We obtained multiple serum samples from 7 obese patients (>50% over their calculated ideal body weight) receiving oral linezolid 600 mg every 12 hours for treatment of cellulitis. Following a minimum of 3 doses, serum concentrations of linezolid were measured in each subject prior to (trough) and 1 and 6 hours after a dose. These samples were then tested against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) ( linezolid minimum inhibitory concentrations [MICs] 1.0, 2.0, 4.0 microg/mL) and one strain each of vancomycin-resistant Enterococcus faecium (VRE) (MIC 2.0 microg/mL), Bacteroides fragilis (MIC 2.0 microg/mL), and Peptostreptococcus magnus (MIC 1.0 microg/mL). Serum inhibitory titers ( SITs) and bactericidal titers (SBTs) were measured at each time point, and the median activity for these 7 patients was calculated. RESULTS: Mean linezolid serum concentrations were 4.2, 12.3, and 7.2 microg/mL at these respective time points. Median SITs for 12 hours (100% of the dosing interval) were observed against each organism with the exception of the least susceptible strain of MRSA (MIC 4.0 microg/mL); serum inhibitory activity was observed only at the one-hour time point against this isolate. Furthermore, prolonged (> or =6 h) median SBTs were observed against one isolate of MRSA (MIC 1.0 microg/mL) as well as the strain of VRE and P. magnus. CONCLUSIONS: Serum concentrations of oral linezolid in this patient population were diminished compared with those of healthy volunteers, but still provided prolonged serum inhibitory activity against common pathogens associated with skin/ soft tissue infections. One treatment concern would be an obese patient receiving oral linezolid who was infected with a less susceptible (MIC > or =4.0 microg/mL) strain of S. aureus. Bactericidal activity was also observed against selective pathogens.
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Authors | Gary E Stein, Sharon L Schooley, Charles A Peloquin, Vivek Kak, Daniel H Havlichek, Diane M Citron, Kerin L Tyrrell, Ellie J C Goldstein |
Journal | The Annals of pharmacotherapy
(Ann Pharmacother)
Vol. 39
Issue 3
Pg. 427-32
(Mar 2005)
ISSN: 1060-0280 [Print] United States |
PMID | 15701775
(Publication Type: Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Acetamides
- Anti-Bacterial Agents
- Oxazolidinones
- Linezolid
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Topics |
- Acetamides
(pharmacokinetics, pharmacology)
- Adult
- Aged
- Aged, 80 and over
- Anti-Bacterial Agents
(pharmacokinetics, pharmacology)
- Area Under Curve
- Cellulitis
(complications, drug therapy, microbiology)
- Drug Resistance, Multiple, Bacterial
- Female
- Half-Life
- Humans
- Linezolid
- Male
- Microbial Sensitivity Tests
- Middle Aged
- Obesity
(complications)
- Oxazolidinones
(pharmacokinetics, pharmacology)
- Serum Bactericidal Test
- Skin Diseases, Bacterial
(complications, drug therapy, microbiology)
- Soft Tissue Infections
(complications, drug therapy, microbiology)
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