Pharmacotherapeutic group: quinolone antibacterials, fluoroquinolones.
ATC code: J01MA12.
Pharmacology: Pharmacodynamics: Levofloxacin is a synthetic antibacterial agent of the fluoroquinolone class and is the S (-) enantiomer of the racemic active substance ofloxacin.
Mechanism of action: As a fluoroquinolone antibacterial agent, levofloxacin acts on the DNA-gyrase complex and topoisomerase IV.
PK/PD relationship: The degree of the bactericidal activity of levofloxacin depends on the ratio of the maximum concentration in serum (Cmax) or the area under the curve (AUC) and the minimal inhibitory concentration (MIC).
Mechanism of resistance: Resistance to levofloxacin is acquired through a stepwise process by target site mutations in both type II topoisomerases, DNA gyrase and topoisomerase IV. Other resistance mechanisms such as permeation barriers (common in
Pseudomonas aeruginosa) and efflux mechanisms may also affect susceptibility to levofloxacin.
Cross-resistance between levofloxacin and other fluoroquinolones is observed. Due to the mechanism of action, there is generally no cross-resistance between levofloxacin and other classes of antibacterial agents.
Breakpoints: The EUCAST recommended MIC breakpoints for levofloxacin, separating susceptible from intermediately susceptible organisms and intermediately susceptible from resistant organisms are presented in Table 1 for MIC testing (mg/l). (See Table 1.)
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The prevalence of resistance may vary geographically and with time for selected species and local information on resistance is desirable, particularly when treating severe infections. As necessary, expert advice should be sought when the local prevalence of resistance is such that the utility of the agent in at least some types of infections is questionable.
Commonly susceptible species: Aerobic Gram-positive bacteria:
Bacillus anthracis,
Staphylococcus aureus methicillin-susceptible,
Staphylococcus saprophyticus, Streptococci group C and G,
Streptococcus agalactiae,
Streptococcus pneumoniae,
Streptococcus pyogenes.
Aerobic Gram-negative bacteria:
Eikenella corrodens,
Haemophilus influenzae,
Haemophilus parainfluenzae,
Klebsiella oxytoca,
Moraxella catarrhalis,
Pasteurella multocida,
Proteus vulgaris,
Providencia rettgeri.
Anaerobic bacteria: Peptostreptococcus.
Other:
Chlamydophila pneumoniae,
Chlamydophila psittaci,
Chlamydia trachomatis,
Legionella pneumophila,
Mycoplasma pneumoniae,
Mycoplasma hominis,
Ureaplasma urealyticum.
Species for which acquired resistance may be a problem: Aerobic Gram-positive bacteria:
Enterococcus faecalis,
Staphylococcus aureus methicillin-resistant
#, coagulase negative
Staphylococcus spp.
Aerobic Gram-negative bacteria:
Acinetobacter baumannii,
Citrobacter freundii,
Enterobacter aerogenes,
Enterobacter agglomerans,
Enterobacter cloacae,
Escherichia coli,
Klebsiella pneumoniae,
Morganella morganii,
Proteus mirabilis,
Providencia stuartii,
Pseudomonas aeruginosa,
Serratia marcescens.
Anaerobic bacteria:
Bacteroides fragilis.
Inherently Resistant Strains: Aerobic Gram-positive bacteria:
Enterococcus faecium.
# Methicillin-resistant
S. aureus are very likely to possess co-resistance to fluoroquinolones, including levofloxacin.
Pharmacokinetics: Absorption: Orally administered levofloxacin is rapidly and almost completely absorbed with peak plasma concentrations being obtained within 1-2 h. The absolute bioavailability is 99-100%.
Food has little effect on the absorption of levofloxacin.
Steady state conditions are reached within 48 hours following a 500 mg once or twice daily dosage regimen.
Distribution: Approximately 30-40% of levofloxacin is bound to serum protein.
The mean volume of distribution of levofloxacin is approximately 100 l after single and repeated 500 mg doses, indicating widespread distribution into body tissues.
Penetration into tissues and body fluids: Levofloxacin has been shown to penetrate into bronchial mucosa, epithelial lining fluid, alveolar macrophages, lung tissue, skin (blister fluid), prostatic tissue and urine. However, levofloxacin has poor penetration into cerebrospinal fluid.
Biotransformation: Levofloxacin is metabolised to a very small extent, the metabolites being desmethyl-levofloxacin and levofloxacin N-oxide. These metabolites account for <5% of the dose excreted in urine. Levofloxacin is stereochemically stable and does not undergo chiral inversion.
Elimination: Following oral and intravenous administration of levofloxacin, it is eliminated relatively slowly from the plasma (t½: 6-8 h). Excretion is primarily by the renal route (>85% of the administered dose).
The mean apparent total body clearance of levofloxacin following a 500 mg single dose was 175 +/- 29.2 ml/min.
There are no major differences in the pharmacokinetics of levofloxacin following intravenous and oral administration, suggesting that the oral and intravenous routes are interchangeable.
Linearity: Levofloxacin obeys linear pharmacokinetics over a range of 50 to 1000 mg.
Special populations: Subjects with renal insufficiency: The pharmacokinetics of levofloxacin are affected by renal impairment. With decreasing renal function renal elimination and clearance are decreased, and elimination half-lives increased as shown in Table 2. (See Table 2.)
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Elderly subjects: There are no significant differences in levofloxacin kinetics between young and elderly subjects, except those associated with differences in creatinine clearance.
Gender differences: Separate analysis for male and female subjects showed small to marginal gender differences in levofloxacin pharmacokinetics. There is no evidence that these gender differences are of clinical relevance.