Levaquin - Pharmacology levofloxacin

Pharmacology refers to the chemical makeup and behavior of LEVAQUIN (levofloxacin tablet, film coated).

Description

LEVAQUIN® Tablets are synthetic antibacterial agents for oral administration. Chemically, levofloxacin, a chiral fluorinated carboxyquinolone, is the pure (-)-(S)-enantiomer of the racemic drug substance ofloxacin. The chemical name is (-)-(S)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H-pyrido[1,2,3-de]-1,4-benzoxazine-6-carboxylic acid hemihydrate.

Figure 1: The Chemical Structure of Levofloxacin

levaquin 01.jpg

The empirical formula is C18H20FN3O4 ∙ ½ H2O and the molecular weight is 370.38. Levofloxacin is a light yellowish-white to yellow-white crystal or crystalline powder. The molecule exists as a zwitterion at the pH conditions in the small intestine.

The data demonstrate that from pH 0.6 to 5.8, the solubility of levofloxacin is essentially constant (approximately 100 mg/mL). Levofloxacin is considered soluble to freely soluble in this pH range, as defined by USP nomenclature. Above pH 5.8, the solubility increases rapidly to its maximum at pH 6.7 (272 mg/mL) and is considered freely soluble in this range. Above pH 6.7, the solubility decreases and reaches a minimum value (about 50 mg/mL) at a pH of approximately 6.9.

Levofloxacin has the potential to form stable coordination compounds with many metal ions. This in vitro chelation potential has the following formation order: Al+3>Cu+2>Zn+2>Mg+2>Ca+2.

LEVAQUIN® Tablets are available as film-coated tablets and contain the following inactive ingredients:

  • 250 mg (as expressed in the anhydrous form): crospovidone, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, synthetic red iron oxide and titanium dioxide.
  • 500 mg (as expressed in the anhydrous form): crospovidone, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, synthetic red and yellow iron oxides and titanium dioxide.
  • 750 mg (as expressed in the anhydrous form): crospovidone, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, titanium dioxide.

Clinical Pharmacology

mechanism of action

Levofloxacin is a member of the fluoroquinolone class of antibacterial agents [see Microbiology (12.4)].

pharmacokinetics

The mean ± SD pharmacokinetic parameters of levofloxacin determined under single and steady-state conditions following administration of the oral tablets, are summarized in Table 8.

Table 8: Mean ± SD Levofloxacin PK Parameters
Regimen Cmax
(mcg/mL)
Tmax
(h)
AUC
(mcg∙h/mL)
CL/F
clearance/bioavailability

(mL/min)

Vd/F
volume of distribution/bioavailability

(L)

t1/2
(h)
CLR
(mL/min)
ND=not determined.
Single dose
250 mg oral tablet
healthy males 18–53 years of age
2.8 ± 0.4 1.6 ± 1.0 27.2 ± 3.9 156 ± 20 ND 7.3 ± 0.9 142 ± 21
500 mg oral tablet
Absolute bioavailability; F=0.99 ± 0.08 from a 500 mg tablet and F=0.99 ± 0.06 from a 750 mg tablet;
5.1 ± 0.8 1.3 ± 0.6 47.9 ± 6.8 178 ± 28 ND 6.3 ± 0.6 103 ± 30
750 mg oral tablet

healthy male and female subjects 18–54 years of age

9.3 ± 1.6 1.6 ± 0.8 101 ± 20 129 ± 24 83 ± 17 7.5 ± 0.9 ND
Multiple dose
500 mg every 24h oral tablet
5.7 ± 1.4 1.1 ± 0.4 47.5 ± 6.7 175 ± 25 102 ± 22 7.6 ± 1.6 116 ± 31
750 mg every 24h oral tablet
8.6 ± 1.9 1.4 ± 0.5 90.7 ± 17.6 143 ± 29 100 ± 16 8.8 ± 1.5 116 ± 28
500 mg oral tablet single dose, effects of gender and age:
Male
healthy males 22–75 years of age
5.5 ± 1.1 1.2 ± 0.4 54.4 ± 18.9 166 ± 44 89 ± 13 7.5 ± 2.1 126 ± 38
Female
healthy females 18–80 years of age
7.0 ± 1.6 1.7 ± 0.5 67.7 ± 24.2 136 ± 44 62 ± 16 6.1 ± 0.8 106 ± 40
Young
young healthy male and female subjects 18–36 years of age
5.5 ± 1.0 1.5 ± 0.6 47.5 ± 9.8 182 ± 35 83 ± 18 6.0 ± 0.9 140 ± 33
Elderly
healthy elderly male and female subjects 66–80 years of age
7.0 ± 1.6 1.4 ± 0.5 74.7 ± 23.3 121 ± 33 67 ± 19 7.6 ± 2.0 91 ± 29
500 mg oral single dose tablet, patients with renal impairment:
CLCR 50–80 mL/min 7.5 ± 1.8 1.5 ± 0.5 95.6 ± 11.8 88 ± 10 ND 9.1 ± 0.9 57 ± 8
CLCR 20–49 mL/min 7.1 ± 3.1 2.1 ± 1.3 182.1 ± 62.6 51 ± 19 ND 27 ± 10 26 ± 13
CLCR <20 mL/min 8.2 ± 2.6 1.1 ± 1.0 263.5 ± 72.5 33 ± 8 ND 35 ± 5 13 ± 3
Hemodialysis 5.7 ± 1.0 2.8 ± 2.2 ND ND ND 76 ± 42 ND
CAPD 6.9 ± 2.3 1.4 ± 1.1 ND ND ND 51 ± 24 ND

Levofloxacin pharmacokinetics are linear and predictable after single and multiple oral or IV dosing regimens. Steady-state conditions are reached within 48 hours following a 500 mg or 750 mg once-daily dosage regimen. The mean ± SD peak and trough plasma concentrations attained following multiple once-daily oral dosage regimens were approximately 5.7 ± 1.4 and 0.5 ± 0.2 mcg/mL after the 500 mg doses, and 8.6 ± 1.9 and 1.1 ± 0.4 mcg/mL after the 750 mg doses, respectively. The mean ± SD peak and trough plasma concentrations attained following multiple once-daily IV regimens were approximately 6.4 ± 0.8 and 0.6 ± 0.2 mcg/mL after the 500 mg doses, and 12.1 ± 4.1 and 1.3 ± 0.71 mcg/mL after the 750 mg doses, respectively.

Absorption

Levofloxacin is rapidly and essentially completely absorbed after oral administration. Peak plasma concentrations are usually attained one to two hours after oral dosing. The absolute bioavailability of levofloxacin from a 500 mg tablet and a 750 mg tablet of LEVAQUIN® are both approximately 99%, demonstrating complete oral absorption of levofloxacin. Following a single intravenous dose of LEVAQUIN® to healthy volunteers, the mean ± SD peak plasma concentration attained was 6.2 ± 1.0 mcg/mL after a 500 mg dose infused over 60 minutes and 11.5 ± 4.0 mcg/mL after a 750 mg dose infused over 90 minutes. Oral administration of a 500 mg dose of LEVAQUIN® with food prolongs the time to peak concentration by approximately 1 hour and decreases the peak concentration by approximately 14% following tablet and approximately 25% following oral solution administration. Therefore, LEVAQUIN® Tablets can be administered without regard to food.

The plasma concentration profile of levofloxacin after IV administration is similar and comparable in extent of exposure (AUC) to that observed for LEVAQUIN® Tablets when equal doses (mg/mg) are administered. Therefore, the oral and IV routes of administration can be considered interchangeable.

Distribution

The mean volume of distribution of levofloxacin generally ranges from 74 to 112 L after single and multiple 500 mg or 750 mg doses, indicating widespread distribution into body tissues. Levofloxacin reaches its peak levels in skin tissues and in blister fluid of healthy subjects at approximately 3 hours after dosing. The skin tissue biopsy to plasma AUC ratio is approximately 2 and the blister fluid to plasma AUC ratio is approximately 1 following multiple once-daily oral administration of 750 mg and 500 mg doses of LEVAQUIN®, respectively, to healthy subjects. Levofloxacin also penetrates well into lung tissues. Lung tissue concentrations were generally 2- to 5-fold higher than plasma concentrations and ranged from approximately 2.4 to 11.3 mcg/g over a 24-hour period after a single 500 mg oral dose.

In vitro, over a clinically relevant range (1 to 10 mcg/mL) of serum/plasma levofloxacin concentrations, levofloxacin is approximately 24 to 38% bound to serum proteins across all species studied, as determined by the equilibrium dialysis method. Levofloxacin is mainly bound to serum albumin in humans. Levofloxacin binding to serum proteins is independent of the drug concentration.

Elimination

Metabolism

Levofloxacin is stereochemically stable in plasma and urine and does not invert metabolically to its enantiomer, D-ofloxacin. Levofloxacin undergoes limited metabolism in humans and is primarily excreted as unchanged drug in the urine. Following oral administration, approximately 87% of an administered dose was recovered as unchanged drug in urine within 48 hours, whereas less than 4% of the dose was recovered in feces in 72 hours. Less than 5% of an administered dose was recovered in the urine as the desmethyl and N-oxide metabolites, the only metabolites identified in humans. These metabolites have little relevant pharmacological activity.

Excretion

Levofloxacin is excreted largely as unchanged drug in the urine. The mean terminal plasma elimination half-life of levofloxacin ranges from approximately 6 to 8 hours following single or multiple doses of levofloxacin given orally or intravenously. The mean apparent total body clearance and renal clearance range from approximately 144 to 226 mL/min and 96 to 142 mL/min, respectively. Renal clearance in excess of the glomerular filtration rate suggests that tubular secretion of levofloxacin occurs in addition to its glomerular filtration. Concomitant administration of either cimetidine or probenecid results in approximately 24% and 35% reduction in the levofloxacin renal clearance, respectively, indicating that secretion of levofloxacin occurs in the renal proximal tubule. No levofloxacin crystals were found in any of the urine samples freshly collected from subjects receiving LEVAQUIN®.

Specific Populations

Geriatric Patients

There are no significant differences in levofloxacin pharmacokinetics between young and elderly subjects when the subjects' differences in creatinine clearance are taken into consideration. Following a 500 mg oral dose of LEVAQUIN® to healthy elderly subjects (66–80 years of age), the mean terminal plasma elimination half-life of levofloxacin was about 7.6 hours, as compared to approximately 6 hours in younger adults. The difference was attributable to the variation in renal function status of the subjects and was not believed to be clinically significant. Drug absorption appears to be unaffected by age. LEVAQUIN® dose adjustment based on age alone is not necessary [see Use in Specific Populations (8.5)].

Pediatric Patients

The pharmacokinetics of levofloxacin following a single 7 mg/kg intravenous dose were investigated in pediatric patients ranging in age from 6 months to 16 years. Pediatric patients cleared levofloxacin faster than adult patients, resulting in lower plasma exposures than adults for a given mg/kg dose. Subsequent pharmacokinetic analyses predicted that a dosage regimen of 8 mg/kg every 12 hours (not to exceed 250 mg per dose) for pediatric patients 6 months to 17 years of age would achieve comparable steady state plasma exposures (AUC0–24 and Cmax) to those observed in adult patients administered 500 mg of levofloxacin once every 24 hours. LEVAQUIN® Tablets can only be administered to pediatric patients with inhalational anthrax (post-exposure) or plague who are 30 kg or greater due to the limitations of the available strengths [see Dosage and Administration (2.2)].

Male and Female Subjects

There are no significant differences in levofloxacin pharmacokinetics between male and female subjects when subjects' differences in creatinine clearance are taken into consideration. Following a 500 mg oral dose of LEVAQUIN® to healthy male subjects, the mean terminal plasma elimination half-life of levofloxacin was about 7.5 hours, as compared to approximately 6.1 hours in female subjects. This difference was attributable to the variation in renal function status of the male and female subjects and was not believed to be clinically significant. Drug absorption appears to be unaffected by the gender of the subjects. Dose adjustment based on gender alone is not necessary.

Racial or Ethnic Groups

The effect of race on levofloxacin pharmacokinetics was examined through a covariate analysis performed on data from 72 subjects: 48 white and 24 non-white. The apparent total body clearance and apparent volume of distribution were not affected by the race of the subjects.

Patients with Renal Impairment

Clearance of levofloxacin is substantially reduced and plasma elimination half-life is substantially prolonged in adult patients with impaired renal function (creatinine clearance < 50 mL/min), requiring dosage adjustment in such patients to avoid accumulation. Neither hemodialysis nor continuous ambulatory peritoneal dialysis (CAPD) is effective in removal of levofloxacin from the body, indicating that supplemental doses of LEVAQUIN® are not required following hemodialysis or CAPD [see Dosage and Administration (2.3) and Use in Specific Populations (8.6)].

Patients with Hepatic Impairment

Pharmacokinetic studies in hepatically impaired patients have not been conducted. Due to the limited extent of levofloxacin metabolism, the pharmacokinetics of levofloxacin are not expected to be affected by hepatic impairment [see Use in Specific Populations (8.7)].

Patients with Bacterial Infection

The pharmacokinetics of levofloxacin in patients with serious community-acquired bacterial infections are comparable to those observed in healthy subjects.

Drug Interaction Studies

The potential for pharmacokinetic drug interactions between LEVAQUIN® and antacids, warfarin, theophylline, cyclosporine, digoxin, probenecid, and cimetidine has been evaluated [see Drug Interactions (7)].

microbiology

Mechanism of Action

Levofloxacin is the L-isomer of the racemate, ofloxacin, a quinolone antimicrobial agent. The antibacterial activity of ofloxacin resides primarily in the L-isomer. The mechanism of action of levofloxacin and other fluoroquinolone antimicrobials involves inhibition of bacterial topoisomerase IV and DNA gyrase (both of which are type II topoisomerases), enzymes required for DNA replication, transcription, repair and recombination.

Resistance

Fluoroquinolone resistance can arise through mutations in defined regions of DNA gyrase or topoisomerase IV, termed the Quinolone-Resistance Determining Regions (QRDRs), or through altered efflux.

Fluoroquinolones, including levofloxacin, differ in chemical structure and mode of action from aminoglycosides, macrolides and β-lactam antibiotics, including penicillins. Fluoroquinolones may, therefore, be active against bacteria resistant to these antimicrobials.

Resistance to levofloxacin due to spontaneous mutation in vitro is a rare occurrence (range: 10-9 to 10-10). Cross-resistance has been observed between levofloxacin and some other fluoroquinolones, some microorganisms resistant to other fluoroquinolones may be susceptible to levofloxacin.

Antimicrobial Activity

Levofloxacin has in vitro activity against Gram-negative and Gram-positive bacteria.

Levofloxacin has been shown to be active against most isolates of the following bacteria both in vitro and in clinical infections as described in Indications and Usage (1):

Aerobic bacteria

  •   Gram-Positive Bacteria
    •   Enterococcus faecalis
    •   Staphylococcus aureus (methicillin-susceptible isolates)
    •   Staphylococcus epidermidis (methicillin-susceptible isolates)
    •   Staphylococcus saprophyticus
    •   Streptococcus pneumoniae (including multi-drug resistant isolates [MDRSP]
      MDRSP (Multi-drug resistant Streptococcus pneumoniae) isolates are isolates resistant to two or more of the following antibiotics: penicillin (MIC ≥2 mcg/mL), 2nd generation cephalosporins, e.g., cefuroxime; macrolides, tetracyclines and trimethoprim/sulfamethoxazole.

      )

    •   Streptococcus pyogenes
  •   Gram-Negative Bacteria
    •   Enterobacter cloacae
    •   Escherichia coli
    •   Haemophilus influenzae
    •   Haemophilus parainfluenzae
    •   Klebsiella pneumoniae
    •   Legionella pneumophila
    •   Moraxella catarrhalis
    •   Proteus mirabilis
    •   Pseudomonas aeruginosa
    •   Serratia marcescens
  •   Other microorganisms
    •   Chlamydophila pneumoniae
    •   Mycoplasma pneumoniae

The following in vitro data are available, but their clinical significance is unknown. At least 90 percent of the following bacteria exhibit an in vitro minimum inhibitory concentrations (MIC) less than or equal to the susceptible breakpoint for LEVAQUIN against isolates of similar genus or organism group. However, efficacy of LEVAQUIN® in treating clinical infections caused by these bacteria has not been established in adequate and well-controlled clinical trials.

Aerobic bacteria

  •   Gram-Positive Bacteria
    •   Staphylococcus haemolyticus
    •   β-hemolytic Streptococcus (Group C/F)
    •  β-hemolytic Streptococcus (Group G)
    •   Streptococcus agalactiae
    •   Streptococcus milleri
    •  Viridans group streptococci
    •   Bacillus anthracis
  •   Gram-Negative Bacteria
    •   Acinetobacter baumannii
    •   Acinetobacter lwoffii
    •   Bordetella pertussis
    •   Citrobacter koseri
    •   Citrobacter freundii
    •   Enterobacter aerogenes
    •   Enterobacter sakazakii
    •   Klebsiella oxytoca
    •   Morganella morganii
    •   Pantoea agglomerans
    •   Proteus vulgaris
    •   Providencia rettgeri
    •   Providencia stuartii
    •   Pseudomonas fluorescens
    •   Yersinia pestis

Anaerobic bacteria

  •   Gram-Positive Bacteria
    •   Clostridium perfringens

Susceptibility Tests

For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see: https://www.fda.gov/STIC.

Nonclinical Toxicology

carcinogenesis, mutagenesis, impairment of fertility

In a lifetime bioassay in rats, levofloxacin exhibited no carcinogenic potential following daily dietary administration for 2 years; the highest dose (100 mg/kg/day) was 1.4 times the Maximum Recommended Human Dose (MRHD) (750 mg) after normalization for total body surface area. Levofloxacin did not shorten the time to tumor development of UV-induced skin tumors in hairless albino (Skh-1) mice at any levofloxacin dose level and was therefore not photo-carcinogenic under conditions of this study. Dermal levofloxacin concentrations in the hairless mice ranged from 25 to 42 mcg/g at the highest levofloxacin dose level (300 mg/kg/day) used in the photo-carcinogenicity study. By comparison, dermal levofloxacin concentrations in human subjects receiving 750 mg of LEVAQUIN® averaged approximately 11.8 mcg/g at Cmax.

Levofloxacin was not mutagenic in the following assays: Ames bacterial mutation assay (S. typhimurium and E. coli), CHO/HGPRT forward mutation assay, mouse micronucleus test, mouse dominant lethal test, rat unscheduled DNA synthesis assay, and the mouse sister chromatid exchange assay. It was positive in the in vitro chromosomal aberration (CHL cell line) and sister chromatid exchange (CHL/IU cell line) assays.

Levofloxacin caused no impairment of fertility or reproductive performance in rats at oral doses as high as 360 mg/kg/day, corresponding to 4.2 times the MRHD and intravenous doses as high as 100 mg/kg/day, corresponding to 1.2 times the MRHD after normalization for total body surface area.

animal toxicology & / or pharmacology

Levofloxacin and other quinolones have been shown to cause arthropathy in immature animals of most species tested [see Warnings and Precautions (5.12)]. In immature dogs (4–5 months old), oral doses of 10 mg/kg/day for 7 days and intravenous doses of 4 mg/kg/day for 14 days of levofloxacin resulted in arthropathic lesions. Administration at oral doses of 300 mg/kg/day for 7 days and intravenous doses of 60 mg/kg/day for 4 weeks produced arthropathy in juvenile rats. Three-month old beagle dogs dosed orally with levofloxacin at 40 mg/kg/day exhibited clinically severe arthrotoxicity resulting in the termination of dosing at Day 8 of a 14-day dosing routine (dosing was terminated in the low and mid-dose groups on Day 9 due to similar findings at the mid-dose). Slight musculoskeletal clinical effects, in the absence of gross pathological or histopathological effects, resulted from the lowest dose level of 2.5 mg/kg/day (approximately 0.2-fold the pediatric dose based upon AUC comparisons). Synovitis and articular cartilage lesions were observed at the 10 and 40 mg/kg dose levels (approximately 0.7-fold and 2.4-fold the pediatric dose, respectively, based on AUC comparisons). Articular cartilage gross pathology and histopathology persisted to the end of the 18-week recovery period for those dogs from the 10 and 40 mg/kg/day dose levels. The low and mid-dose groups in that study were also evaluated by electron microscopy, revealing compound-related ultrastructural effects in articular cartilage chondrocytes at the end of treatment and at the end of recovery in both of those doses.

When tested in a mouse ear swelling bioassay, levofloxacin exhibited phototoxicity similar in magnitude to ofloxacin, but less phototoxicity than other quinolones.

While crystalluria has been observed in some intravenous rat studies, urinary crystals are not formed in the bladder, being present only after micturition and are not associated with nephrotoxicity.

In mice, the CNS stimulatory effect of quinolones is enhanced by concomitant administration of non-steroidal anti-inflammatory drugs.

In dogs, levofloxacin administered at 6 mg/kg or higher by rapid intravenous injection produced hypotensive effects. These effects were considered to be related to histamine release.

In vitro and in vivo studies in animals indicate that levofloxacin is neither an enzyme inducer nor inhibitor in the human therapeutic plasma concentration range; therefore, no drug metabolizing enzyme-related interactions with other drugs or agents are anticipated.

Clinical Studies

nosocomial pneumonia

Adult patients with clinically and radiologically documented nosocomial pneumonia were enrolled in a multicenter, randomized, open-label study comparing intravenous LEVAQUIN® (750 mg once daily) followed by oral LEVAQUIN® (750 mg once daily) for a total of 7–15 days to intravenous imipenem/cilastatin (500–1000 mg every 6–8 hours daily) followed by oral ciprofloxacin (750 mg every 12 hours daily) for a total of 7–15 days. LEVAQUIN®-treated patients received an average of 7 days of intravenous therapy (range: 1–16 days); comparator-treated patients received an average of 8 days of intravenous therapy (range: 1–19 days).

Overall, in the clinically and microbiologically evaluable population, adjunctive therapy was empirically initiated at study entry in 56 of 93 (60.2%) patients in the LEVAQUIN® arm and 53 of 94 (56.4%) patients in the comparator arm. The average duration of adjunctive therapy was 7 days in the LEVAQUIN® arm and 7 days in the comparator. In clinically and microbiologically evaluable patients with documented Pseudomonas aeruginosa infection, 15 of 17 (88.2%) received ceftazidime (N = 11) or piperacillin/tazobactam (N = 4) in the LEVAQUIN® arm and 16 of 17 (94.1%) received an aminoglycoside in the comparator arm. Overall, in clinically and microbiologically evaluable patients, vancomycin was added to the treatment regimen of 37 of 93 (39.8%) patients in the LEVAQUIN® arm and 28 of 94 (29.8%) patients in the comparator arm for suspected methicillin-resistant S. aureus infection.

Clinical success rates in clinically and microbiologically evaluable patients at the post-therapy visit (primary study endpoint assessed on day 3–15 after completing therapy) were 58.1% for LEVAQUIN® and 60.6% for comparator. The 95% CI for the difference of response rates (LEVAQUIN® minus comparator) was [-17.2, 12.0]. The microbiological eradication rates at the posttherapy visit were 66.7% for LEVAQUIN® and 60.6% for comparator. The 95% CI for the difference of eradication rates (LEVAQUIN® minus comparator) was [-8.3, 20.3]. Clinical success and microbiological eradication rates by pathogen are detailed in Table 9.

Table 9: Clinical Success Rates and Bacteriological Eradication Rates (Nosocomial Pneumonia)
Pathogen N LEVAQUIN® No. (%) of Patients Microbiologic/Clinical Outcomes N Imipenem/Cilastatin No. (%) of Patients Microbiologic/Clinical Outcomes
MSSA
Methicillin-susceptible S. aureus
21 14 (66.7)/13 (61.9) 19 13 (68.4)/15 (78.9)
P. aeruginosa
See above text for use of combination therapy
17 10 (58.8)/11 (64.7) 17 5 (29.4)/7 (41.2)
S. marcescens 11 9 (81.8)/7 (63.6) 7 2 (28.6)/3 (42.9)
E. coli 12 10 (83.3)/7 (58.3) 11 7 (63.6)/8 (72.7)
K. pneumoniae
The observed differences in rates for the clinical and microbiological outcomes may reflect other factors that were not accounted for in the study
11 9 (81.8)/5 (45.5) 7 6 (85.7)/3 (42.9)
H. influenzae 16 13 (81.3)/10 (62.5) 15 14 (93.3)/11 (73.3)
S. pneumoniae 4 3 (75.0)/3 (75.0) 7 5 (71.4)/4 (57.1)

community-acquired pneumonia: 7–14 day treatment regimen

Adult inpatients and outpatients with a diagnosis of community-acquired bacterial pneumonia were evaluated in 2 pivotal clinical studies. In the first study, 590 patients were enrolled in a prospective, multi-center, unblinded randomized trial comparing LEVAQUIN® 500 mg once daily orally or intravenously for 7 to 14 days to ceftriaxone 1 to 2 grams intravenously once or in equally divided doses twice daily followed by cefuroxime axetil 500 mg orally twice daily for a total of 7 to 14 days. Patients assigned to treatment with the control regimen were allowed to receive erythromycin (or doxycycline if intolerant of erythromycin) if an infection due to atypical pathogens was suspected or proven. Clinical and microbiologic evaluations were performed during treatment, 5 to 7 days posttherapy, and 3 to 4 weeks posttherapy. Clinical success (cure plus improvement) with LEVAQUIN® at 5 to 7 days posttherapy, the primary efficacy variable in this study, was superior (95%) to the control group (83%). The 95% CI for the difference of response rates (LEVAQUIN® minus comparator) was [-6, 19]. In the second study, 264 patients were enrolled in a prospective, multi-center, non-comparative trial of 500 mg LEVAQUIN® administered orally or intravenously once daily for 7 to 14 days. Clinical success for clinically evaluable patients was 93%. For both studies, the clinical success rate in patients with atypical pneumonia due to Chlamydophila pneumoniae, Mycoplasma pneumoniae, and Legionella pneumophila were 96%, 96%, and 70%, respectively. Microbiologic eradication rates across both studies are presented in Table 10.

Table 10: Bacteriological Eradication Rates Across 2 Community Acquired Pneumonia Clinical Studies
Pathogen No. Pathogens Bacteriological Eradication Rate (%)
H. influenzae 55 98
S. pneumoniae 83 95
S. aureus 17 88
M. catarrhalis 18 94
H. parainfluenzae 19 95
K. pneumoniae 10 100.0

Community-Acquired Pneumonia Due to Multi-Drug Resistant Streptococcus pneumoniae

LEVAQUIN® was effective for the treatment of community-acquired pneumonia caused by multi-drug resistant Streptococcus pneumoniae (MDRSP). MDRSP isolates are isolates resistant to two or more of the following antibacterials: penicillin (MIC ≥2 mcg/mL), 2nd generation cephalosporins (e.g., cefuroxime, macrolides, tetracyclines and trimethoprim/sulfamethoxazole). Of 40 microbiologically evaluable patients with MDRSP isolates, 38 patients (95.0%) achieved clinical and bacteriologic success at post-therapy. The clinical and bacterial success rates are shown in Table 11.

Table 11: Clinical and Bacterial Success Rates for LEVAQUIN ®-Treated MDRSP in Community Acquired Pneumonia Patients (Population Valid for Efficacy)
Screening Susceptibility Clinical Success Bacteriological Success
One patient had a respiratory isolate that was resistant to tetracycline, cefuroxime, macrolides and TMP/SMX and intermediate to penicillin and a blood isolate that was intermediate to penicillin and cefuroxime and resistant to the other classes. The patient is included in the database based on respiratory isolate.
n/N
n = the number of microbiologically evaluable patients who were clinical successes; N = number of microbiologically evaluable patients in the designated resistance group.
% n/N
n = the number of MDRSP isolates eradicated or presumed eradicated in microbiologically evaluable patients; N = number of MDRSP isolates in a designated resistance group.
%
Penicillin-resistant 16/17 94.1 16/17 94.1
2nd generation Cephalosporin resistant 31/32 96.9 31/32 96.9
Macrolide-resistant 28/29 96.6 28/29 96.6
Trimethoprim/ Sulfamethoxazole resistant 17/19 89.5 17/19 89.5
Tetracycline-resistant 12/12 100 12/12 100

Not all isolates were resistant to all antimicrobial classes tested. Success and eradication rates are summarized in Table 12.

Table 12: Clinical Success and Bacteriologic Eradication Rates for Resistant Streptococcus pneumoniae (Community Acquired Pneumonia)
Type of Resistance Clinical Success Bacteriologic Eradication
Resistant to 2 antibacterials 17/18 (94.4%) 17/18 (94.4%)
Resistant to 3 antibacterials 14/15 (93.3%) 14/15 (93.3%)
Resistant to 4 antibacterials 7/7 (100%) 7/7 (100%)
Resistant to 5 antibacterials 0 0
Bacteremia with MDRSP 8/9 (89%) 8/9 (89%)

community-acquired pneumonia: 5-day treatment regimen

To evaluate the safety and efficacy of the higher dose and shorter course of LEVAQUIN®, 528 outpatient and hospitalized adults with clinically and radiologically determined mild to severe community-acquired pneumonia were evaluated in a double-blind, randomized, prospective, multicenter study comparing LEVAQUIN® 750 mg, IV or orally, every day for five days or LEVAQUIN® 500 mg IV or orally, every day for 10 days.

Clinical success rates (cure plus improvement) in the clinically evaluable population were 90.9% in the LEVAQUIN® 750 mg group and 91.1% in the LEVAQUIN® 500 mg group. The 95% CI for the difference of response rates (LEVAQUIN® 750 minus LEVAQUIN® 500) was [-5.9, 5.4]. In the clinically evaluable population (31–38 days after enrollment) pneumonia was observed in 7 out of 151 patients in the LEVAQUIN® 750 mg group and 2 out of 147 patients in the LEVAQUIN® 500 mg group. Given the small numbers observed, the significance of this finding cannot be determined statistically. The microbiological efficacy of the 5-day regimen was documented for infections listed in Table 13.

Table 13: Bacteriological Eradication Rates (Community-Acquired Pneumonia)
S. pneumoniae 19/20 (95%)
Haemophilus influenzae 12/12 (100%)
Haemophilus parainfluenzae 10/10 (100%)
Mycoplasma pneumoniae 26/27 (96%)
Chlamydophila pneumoniae 13/15 (87%)

acute bacterial sinusitis: 5-day & 10–14 day treatment regimens

LEVAQUIN® is approved for the treatment of acute bacterial sinusitis (ABS) using either 750 mg by mouth × 5 days or 500 mg by mouth once daily × 10–14 days. To evaluate the safety and efficacy of a high dose short course of LEVAQUIN®, 780 outpatient adults with clinically and radiologically determined acute bacterial sinusitis were evaluated in a double-blind, randomized, prospective, multicenter study comparing LEVAQUIN® 750 mg by mouth once daily for five days to LEVAQUIN® 500 mg by mouth once daily for 10 days.

Clinical success rates (defined as complete or partial resolution of the pre-treatment signs and symptoms of ABS to such an extent that no further antibiotic treatment was deemed necessary) in the microbiologically evaluable population were 91.4% (139/152) in the LEVAQUIN® 750 mg group and 88.6% (132/149) in the LEVAQUIN® 500 mg group at the test-of-cure (TOC) visit (95% CI [-4.2, 10.0] for LEVAQUIN® 750 mg minus LEVAQUIN® 500 mg).

Rates of clinical success by pathogen in the microbiologically evaluable population who had specimens obtained by antral tap at study entry showed comparable results for the five- and ten-day regimens at the test-of-cure visit 22 days post treatment (see Table 14).

Table 14: Clinical Success Rate by Pathogen at the TOC in Microbiologically Evaluable Subjects Who Underwent Antral Puncture (Acute Bacterial Sinusitis)
Pathogen LEVAQUIN® 750 mg × 5 days LEVAQUIN® 500 mg × 10 days
Streptococcus pneumoniae
Note: Forty percent of the subjects in this trial had specimens obtained by sinus endoscopy. The efficacy data for subjects whose specimen was obtained endoscopically were comparable to those presented in the above table.
25/27 (92.6%) 26/27 (96.3%)
Haemophilus influenzae
19/21 (90.5%) 25/27 (92.6%)
Moraxella catarrhalis
10/11 (90.9%) 13/13 (100%)

complicated skin & skin structure infections

Three hundred ninety-nine patients were enrolled in an open-label, randomized, comparative study for complicated skin and skin structure infections. The patients were randomized to receive either LEVAQUIN® 750 mg once daily (IV followed by oral), or an approved comparator for a median of 10 ± 4.7 days. As is expected in complicated skin and skin structure infections, surgical procedures were performed in the LEVAQUIN® and comparator groups. Surgery (incision and drainage or debridement) was performed on 45% of the LEVAQUIN®-treated patients and 44% of the comparator-treated patients, either shortly before or during antibiotic treatment and formed an integral part of therapy for this indication.

Among those who could be evaluated clinically 2–5 days after completion of study drug, overall success rates (improved or cured) were 116/138 (84.1%) for patients treated with LEVAQUIN® and 106/132 (80.3%) for patients treated with the comparator.

Success rates varied with the type of diagnosis ranging from 68% in patients with infected ulcers to 90% in patients with infected wounds and abscesses. These rates were equivalent to those seen with comparator drugs.

chronic bacterial prostatitis

Adult patients with a clinical diagnosis of prostatitis and microbiological culture results from urine sample collected after prostatic massage (VB3) or expressed prostatic secretion (EPS) specimens obtained via the Meares-Stamey procedure were enrolled in a multicenter, randomized, double-blind study comparing oral LEVAQUIN® 500 mg, once daily for a total of 28 days to oral ciprofloxacin 500 mg, twice daily for a total of 28 days. The primary efficacy endpoint was microbiologic efficacy in microbiologically evaluable patients. A total of 136 and 125 microbiologically evaluable patients were enrolled in the LEVAQUIN® and ciprofloxacin groups, respectively. The microbiologic eradication rate by patient infection at 5–18 days after completion of therapy was 75.0% in the LEVAQUIN® group and 76.8% in the ciprofloxacin group (95% CI [-12.58, 8.98] for LEVAQUIN® minus ciprofloxacin). The overall eradication rates for pathogens of interest are presented in Table 15.

Table 15: Bacteriological Eradication Rates (Chronic Bacterial Prostatitis)
LEVAQUIN® (N = 136) Ciprofloxacin (N = 125)
Pathogen N Eradication N Eradication
E. coli 15 14 (93.3%) 11 9 (81.8%)
E. faecalis 54 39 (72.2%) 44 33 (75.0%)
S. epidermidis
Eradication rates shown are for patients who had a sole pathogen only; mixed cultures were excluded.
11 9 (81.8%) 14 11 (78.6%)

Eradication rates for S. epidermidis when found with other co-pathogens are consistent with rates seen in pure isolates.

Clinical success (cure + improvement with no need for further antibiotic therapy) rates in microbiologically evaluable population 5–18 days after completion of therapy were 75.0% for LEVAQUIN®-treated patients and 72.8% for ciprofloxacin-treated patients (95% CI [-8.87, 13.27] for LEVAQUIN® minus ciprofloxacin). Clinical long-term success (24–45 days after completion of therapy) rates were 66.7% for the LEVAQUIN®-treated patients and 76.9% for the ciprofloxacin-treated patients (95% CI [-23.40, 2.89] for LEVAQUIN® minus ciprofloxacin).

complicated urinary tract infections & acute pyelonephritis: 5-day treatment regimen

To evaluate the safety and efficacy of the higher dose and shorter course of LEVAQUIN®, 1109 patients with cUTI and AP were enrolled in a randomized, double-blind, multicenter clinical trial conducted in the US from November 2004 to April 2006 comparing LEVAQUIN® 750 mg IV or orally once daily for 5 days (546 patients) with ciprofloxacin 400 mg IV or 500 mg orally twice daily for 10 days (563 patients). Patients with AP complicated by underlying renal diseases or conditions such as complete obstruction, surgery, transplantation, concurrent infection or congenital malformation were excluded. Efficacy was measured by bacteriologic eradication of the baseline organism(s) at the post-therapy visit in patients with a pathogen identified at baseline. The post-therapy (test-of-cure) visit occurred 10 to 14 days after the last active dose of LEVAQUIN® and 5 to 9 days after the last dose of active ciprofloxacin.

The bacteriologic cure rates overall for LEVAQUIN® and control at the test-of-cure (TOC) visit for the group of all patients with a documented pathogen at baseline (modified intent to treat or mITT) and the group of patients in the mITT population who closely followed the protocol (Microbiologically Evaluable) are summarized in Table 16.

Table 16: Bacteriological Eradication at Test-of-Cure
LEVAQUIN® 750 mg orally or IV once daily for 5 days Ciprofloxacin 400 mg IV/500 mg orally twice daily for 10 days Overall Difference [95% CI]
n/N % n/N % LEVAQUIN®-Ciprofloxacin
mITT Population
The mITT population included patients who received study medication and who had a positive (≥10 5 CFU/mL) urine culture with no more than 2 uropathogens at baseline. Patients with missing response were counted as failures in this analysis.
Overall (cUTI or AP) 252/333 75.7 239/318 75.2 0.5 (-6.1, 7.1)
cUTI 168/230 73.0 157/213 73.7
AP 84/103 81.6 82/105 78.1
Microbiologically Evaluable Population
The Microbiologically Evaluable population included patients with a confirmed diagnosis of cUTI or AP, a causative organism(s) at baseline present at ≥10 5 CFU/mL, a valid test-of-cure urine culture, no pathogen isolated from blood resistant to study drug, no premature discontinuation or loss to follow-up, and compliance with treatment (among other criteria).
Overall (cUTI or AP) 228/265 86.0 215/241 89.2 -3.2 [-8.9, 2.5]
cUTI 154/185 83.2 144/165 87.3
AP 74/80 92.5 71/76 93.4

Microbiologic eradication rates in the Microbiologically Evaluable population at TOC for individual pathogens recovered from patients randomized to LEVAQUIN® treatment are presented in Table 17.

Table 17: Bacteriological Eradication Rates for Individual Pathogens Recovered From Patients Randomized to LEVAQUIN ® 750 mg QD for 5 Days Treatment
Pathogen Bacteriological Eradication Rate
(n/N)
%
Escherichia coli
The predominant organism isolated from patients with AP was E. coli: 91% (63/69) eradication in AP and 89% (92/103) in patients with cUTI.
155/172 90
Klebsiella pneumoniae 20/23 87
Proteus mirabilis 12/12 100

complicated urinary tract infections & acute pyelonephritis: 10-day treatment regimen

To evaluate the safety and efficacy of the 250 mg dose, 10 day regimen of LEVAQUIN®, 567 patients with uncomplicated UTI, mild-to-moderate cUTI, and mild-to-moderate AP were enrolled in a randomized, double-blind, multicenter clinical trial conducted in the US from June 1993 to January 1995 comparing LEVAQUIN® 250 mg orally once daily for 10 days (285 patients) with ciprofloxacin 500 mg orally twice daily for 10 days (282 patients). Patients with a resistant pathogen, recurrent UTI, women over age 55 years, and with an indwelling catheter were initially excluded, prior to protocol amendment which took place after 30% of enrollment. Microbiological efficacy was measured by bacteriologic eradication of the baseline organism(s) at 1–12 days post-therapy in patients with a pathogen identified at baseline.

The bacteriologic cure rates overall for LEVAQUIN® and control at the test-of-cure (TOC) visit for the group of all patients with a documented pathogen at baseline (modified intent to treat or mITT) and the group of patients in the mITT population who closely followed the protocol (Microbiologically Evaluable) are summarized in Table 18.

Table 18: Bacteriological Eradication Overall (cUTI or AP) at Test-Of-Cure
1–9 days posttherapy for 30% of subjects enrolled prior to a protocol amendment; 5–12 days posttherapy for 70% of subjects.
LEVAQUIN®
250 mg once daily for 10 days
Ciprofloxacin
500 mg twice daily for 10 days
n/N % n/N %
mITT Population
The mITT population included patients who had a pathogen isolated at baseline. Patients with missing response were counted as failures in this analysis.
174/209 83.3 184/219 84.0
Microbiologically Evaluable Population
The Microbiologically Evaluable population included mITT patients who met protocol-specified evaluability criteria.
164/177 92.7 159/171 93.0

inhalational anthrax (post-exposure)

The effectiveness of LEVAQUIN® for this indication is based on plasma concentrations achieved in humans, a surrogate endpoint reasonably likely to predict clinical benefit. LEVAQUIN® has not been tested in humans for the post-exposure prevention of inhalation anthrax. The mean plasma concentrations of LEVAQUIN® associated with a statistically significant improvement in survival over placebo in the rhesus monkey model of inhalational anthrax are reached or exceeded in adult and pediatric patients receiving the recommended oral and intravenous dosage regimens [see Indications and Usage (1.13) and Dosage and Administration (2.1 , 2.2)].

Levofloxacin pharmacokinetics have been evaluated in adult and pediatric patients. The mean (± SD) steady state peak plasma concentration in human adults receiving 500 mg orally or intravenously once daily is 5.7 ± 1.4 and 6.4 ± 0.8 mcg/mL, respectively; and the corresponding total plasma exposure (AUC0–24) is 47.5 ± 6.7 and 54.6 ± 11.1 mcg.h/mL, respectively. The predicted steady-state pharmacokinetic parameters in pediatric patients ranging in age from 6 months to 17 years receiving 8 mg/kg orally every 12 hours (not to exceed 250 mg per dose) were calculated to be comparable to those observed in adults receiving 500 mg orally once daily [see Clinical Pharmacology (12.3)]. LEVAQUIN® Tablets can only be administered to pediatric patients with inhalational anthrax (post-exposure) or plague who are 30 kg or greater due to the limitations of the available strengths [see Dosage and Administration (2.2)].

In adults, the safety of LEVAQUIN® for treatment durations of up to 28 days is well characterized. However, information pertaining to extended use at 500 mg daily up to 60 days is limited. Prolonged LEVAQUIN® therapy in adults should only be used when the benefit outweighs the risk.

In pediatric patients, the safety of levofloxacin for treatment durations of more than 14 days has not been studied. An increased incidence of musculoskeletal adverse events (arthralgia, arthritis, tendinopathy, gait abnormality) compared to controls has been observed in clinical studies with treatment duration of up to 14 days. Long-term safety data, including effects on cartilage, following the administration of levofloxacin to pediatric patients is limited [see Warnings and Precautions (5.12) and Use in Specific Populations (8.4)].

A placebo-controlled animal study in rhesus monkeys exposed to an inhaled mean dose of 49 LD50 (~2.7 × 106) spores (range 17 – 118 LD50) of B. anthracis (Ames strain) was conducted. The minimal inhibitory concentration (MIC) of levofloxacin for the anthrax strain used in this study was 0.125 mcg/mL. In the animals studied, mean plasma concentrations of levofloxacin achieved at expected Tmax (1 hour post-dose) following oral dosing to steady state ranged from 2.79 to 4.87 mcg/mL. Steady state trough concentrations at 24 hours post-dose ranged from 0.107 to 0.164 mcg/mL. Mean (SD) steady state AUC0–24 was 33.4 ± 3.2 mcg.h/mL (range 30.4 to 36.0 mcg.h/mL). Mortality due to anthrax for animals that received a 30 day regimen of oral LEVAQUIN® beginning 24 hrs post exposure was significantly lower (1/10), compared to the placebo group (9/10) [P = 0.0011, 2-sided Fisher's Exact Test]. The one levofloxacin treated animal that died of anthrax did so following the 30-day drug administration period.

plague

Efficacy studies of LEVAQUIN® could not be conducted in humans with pneumonic plague for ethical and feasibility reasons. Therefore, approval of this indication was based on an efficacy study conducted in animals.

The mean plasma concentrations of LEVAQUIN® associated with a statistically significant improvement in survival over placebo in an African green monkey model of pneumonic plague are reached or exceeded in adult and pediatric patients receiving the recommended oral and intravenous dosage regimens [see Indications and Usage (1.14) and Dosage and Administration (2.1) , (2.2)].

Levofloxacin pharmacokinetics have been evaluated in adult and pediatric patients. The mean (± SD) steady state peak plasma concentration in human adults receiving 500 mg orally or intravenously once daily is 5.7 ± 1.4 and 6.4 ± 0.8 mcg/mL, respectively; and the corresponding total plasma exposure (AUC0–24) is 47.5 ± 6.7 and 54.6 ± 11.1 mcg.h/mL, respectively. The predicted steady-state pharmacokinetic parameters in pediatric patients ranging in age from 6 months to 17 years receiving 8 mg/kg orally every 12 hours (not to exceed 250 mg per dose) were calculated to be comparable to those observed in adults receiving 500 mg orally once daily [see Clinical Pharmacology (12.3)]. LEVAQUIN® Tablets can only be administered to pediatric patients with inhalational anthrax (post-exposure) or plague who are 30 kg or greater due to the limitations of the available strengths [see Dosage and Administration (2.2)].

A placebo-controlled animal study in African green monkeys exposed to an inhaled mean dose of 65 LD50 (range 3 to 145 LD50) of Yersinia pestis (CO92 strain) was conducted. The minimal inhibitory concentration (MIC) of levofloxacin for the Y. pestis strain used in this study was 0.03 mcg/mL. Mean plasma concentrations of levofloxacin achieved at the end of a single 30-min infusion ranged from 2.84 to 3.50 mcg/mL in African green monkeys. Trough concentrations at 24 hours post-dose ranged from <0.03 to 0.06 mcg/mL. Mean (SD) AUC0–24 was 11.9 (3.1) mcg.h/mL (range 9.50 to 16.86 mcg.h/mL). Animals were randomized to receive either a 10-day regimen of i.v. LEVAQUIN® or placebo beginning within 6 hrs of the onset of telemetered fever (≥ 39°C for more than 1 hour). Mortality in the LEVAQUIN® group was significantly lower (1/17) compared to the placebo group (7/7) [p<0.001, Fisher's Exact Test; exact 95% confidence interval (-99.9%, -55.5%) for the difference in mortality]. One levofloxacin-treated animal was euthanized on Day 9 post-exposure to Y. pestis due to a gastric complication; it had a blood culture positive for Y. pestis on Day 3 and all subsequent daily blood cultures from Day 4 through Day 7 were negative.

This drug label information is as submitted to the Food and Drug Administration (FDA) and is intended for informational purposes only. If you think you may have a medical emergency, immediately call your doctor or dial 911. You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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