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CLINICAL PHARMACOLOGY

Pharmacokinetics

The pharmacokinetics of gemifloxacin are approximately linear over the dose range from 40 mg to 640 mg. There was minimal accumulation of gemifloxacin following multiple oral doses up to 640 mg a day for 7 days (mean accumulation <20%). Following repeat oral administration of 320 mg gemifloxacin once daily, steady-state is achieved by the third day of dosing.

Absorption and Bioavailability

Gemifloxacin, given as an oral tablet, is rapidly absorbed from the gastrointestinal tract. Peak plasma concentrations of gemifloxacin were observed between 0.5 and 2 hours following oral tablet administration and the absolute bioavailability of the 320 mg tablet averaged approximately 71% (95% CI 60%-84%). Following repeat oral doses of 320 mg to healthy subjects, the mean ± SD maximal gemifloxacin plasma concentrations (Cmax) and systemic drug exposure (AUC (0-24)) were 1.61 ± 0.51 μg/mL (range 0.70-2.62 μg/mL) and 9.93 ± 3.07 μg•hr/mL (range 4.71-20.1 μg•hr/mL), respectively. In patients with respiratory and urinary tract infections (n=1423), similar estimates of systemic drug exposure were determined using a population pharmacokinetics analysis (geometric mean AUC (0-24), 8.36 μg•hr/mL; range 3.2 – 47.7 μg•hr/mL).

The pharmacokinetics of gemifloxacin were not significantly altered when a 320 mg dose was administered with a high-fat meal. Therefore FACTIVE tablets may be administered without regard to meals.

Distribution

In vitro binding of gemifloxacin to plasma proteins in healthy subjects is approximately 60 to 70% and is concentration independent. After repeated doses, the in vivo plasma protein binding in healthy elderly and young subjects ranged from 55% to 73% and was unaffected by age. Renal impairment does not significantly affect the protein binding of gemifloxacin. The blood-to-plasma concentration ratio of gemifloxacin was 1.2:1. The geometric mean for Vdss/F is 4.18 L/kg (range, 1.66 – 12.12 L/kg).

Gemifloxacin is widely distributed throughout the body after oral administration. Concentrations of gemifloxacin in bronchoalveolar lavage fluid exceed those in the plasma. Gemifloxacin penetrates well into lung tissue and fluids. After five daily doses of 320 mg gemifloxacin, concentrations in plasma, bronchoalveolar macrophages, epithelial lining fluid and bronchial mucosa at approximately 2 hours were as in Table 1.

Table 1: Gemifloxacin Concentrations in Plasma and Tissues (320 mg Oral Dosing)

Tissue Concentration (mean ± SD) Ratio compared with plasma(mean ± SD)
Plasma 1.40 (0.442) μg/mL -
Bronchoalveolar Macrophages 107 (77) μg/g 90.5 (106.3)
Epithelial Lining Fluid 2.69 (1.96) μg/mL 1.99 (1.32)
Bronchial Mucosa 9.52 (5.15) μg/g 7.21 (4.03)

Metabolism

Gemifloxacin is metabolized to a limited extent by the liver. The unchanged compound is the predominant drug-related component detected in plasma (approximately 65%) up to 4 hours after dosing. All metabolites formed are minor (<10% of the administered oral dose); the principal ones are N-acetyl gemifloxacin, the E-isomer of gemifloxacin and the carbamyl glucuronide of gemifloxacin. Cytochrome P450 enzymes do not play an important role in gemifloxacin metabolism, and the metabolic activity of these enzymes is not significantly inhibited by gemifloxacin.

Excretion

Gemifloxacin and its metabolites are excreted via dual routes of excretion. Following oral administration of gemifloxacin to healthy subjects, a mean (± SD) of 61 ± 9.5% of the dose was excreted in the feces and 36 ± 9.3% in the urine as unchanged drug and metabolites. The mean (± SD) renal clearance following repeat doses of 320 mg was approximately 11.6 ± 3.9 L/hr (range 4.6-17.6 L/hr), which indicates active secretion is involved in the renal excretion of gemifloxacin. The mean (± SD) plasma elimination half-life at steady state following 320 mg to healthy subjects was approximately 7 ± 2 hours (range 4-12 hours).

Special Populations

Pediatric: The pharmacokinetics of gemifloxacin in pediatric subjects have not been studied.

Geriatric: In adult subjects, the pharmacokinetics of gemifloxacin are not affected by age.

Gender: There are no significant differences between gemifloxacin pharmacokinetics in males and females when differences in body weight are taken into account. Population pharmacokinetic studies indicated that following administration of 320 mg gemifloxacin, AUC values were approximately 10% higher in healthy female patients compared to males. Males and females had mean AUC values of 7.98 μg•hr/mL (range, 3.21 – 42.71 μg•hr/mL) and 8.80 μg•hr/mL (range, 3.33 – 47.73 μg•hr/mL), respectively. No gemifloxacin dosage adjustment based on gender is necessary.

Hepatic Insufficiency: The pharmacokinetics following a single 320 mg dose of gemifloxacin were studied in patients with mild (Child-Pugh Class A) to moderate (Child-Pugh Class B) liver disease. There was a mean increase in AUC (0-inf) of 34% and a mean increase in Cmax of 25% in these patients with hepatic impairment compared to healthy volunteers.

The pharmacokinetics of a single 320 mg dose of gemifloxacin were also studied in patients with severe hepatic impairment (Child-Pugh Class C). There was a mean increase in AUC (0-inf) of 45% and a mean increase in Cmax of 41% in these subjects with hepatic impairment compared to healthy volunteers.

These average pharmacokinetic increases are not considered to be clinically significant. There was no significant change in plasma elimination half-life in the mild, moderate or severe hepatic impairment patients. No dosage adjustment is recommended in patients with mild (Child-Pugh Class A), moderate (Child-Pugh Class B) or severe (Child-Pugh Class C) hepatic impairment. (See DOSAGE AND ADMINISTRATION.)

Renal Insufficiency: Results from population pharmacokinetic and clinical pharmacology studies with repeated 320 mg doses indicate the clearance of gemifloxacin is reduced and the plasma elimination is prolonged, leading to an average increase in AUC values of approximately 70% in patients with renal insufficiency. In the pharmacokinetic studies, gemifloxacin Cmax was not significantly altered in subjects with renal insufficiency. Dose adjustment in patients with creatinine clearance >40 mL/min is not required. Modification of the dosage is recommended for patients with creatinine clearance ≤40 mL/min. (See DOSAGE AND ADMINISTRATION.)

Hemodialysis removes approximately 20 to 30% of an oral dose of gemifloxacin from plasma.

Photosensitivity Potential

In a study of the skin response to ultraviolet and visible radiation conducted in 40 healthy volunteers, the minimum erythematous dose (MED) was assessed following administration of either gemifloxacin 160 mg once daily, gemifloxacin 320 mg once daily, ciprofloxacin 500 mg BID, or placebo for 7 days. At 5 of the 6 wavelengths tested (295-430 nm), the photosensitivity potential of gemifloxacin was not statistically different from placebo. At 365 nm (UVA region), gemifloxacin showed a photosensitivity potential similar to that of ciprofloxacin 500 mg BID and the photosensitivity potential for both drugs were statistically greater than that of placebo. Photosensitivity reactions were reported rarely in clinical trials with gemifloxacin (0.039%). (See ADVERSE REACTIONS.)

It is difficult to ascribe relative photosensitivity/phototoxicity among various fluoroquinolones during actual patient use because other factors play a role in determining a subject's susceptibility to this adverse event such as: a patient's skin pigmentation, frequency and duration of sun and artificial ultraviolet light (UV) exposure, wearing of sun screen and protective clothing, the use of other concomitant drugs and the dosage and duration of fluoroquinolone therapy. (See ADVERSE REACTIONS and ADVERSE REACTIONS: Post-Marketing Adverse Reactions.)

Drug-Drug Interactions

Antacids/Di-and Trivalent Cations: The systemic availability of gemifloxacin is significantly reduced when an aluminum-and magnesium-containing antacid is concomitantly administered (AUC decreased 85%; Cmax decreased 87%). Administration of an aluminum-and magnesium-containing antacid or ferrous sulfate (325 mg) at 3 hours before or at 2 hours after gemifloxacin did not significantly alter the systemic availability of gemifloxacin. Therefore, aluminum-and/or magnesium-containing antacids, ferrous sulfate (iron), multivitamin preparations containing zinc or other metal cations, or Videx®(didanosine) chewable/buffered tablets or the pediatric powder for oral solution should not be taken within 3 hours before or 2 hours after taking FACTIVE tablets.

Calcium carbonate (1000 mg) given either 2 hr before or 2 hr after gemifloxacin administration showed no notable reduction in gemifloxacin systemic availability. Calcium carbonate administered simultaneously with gemifloxacin resulted in a small, not clinically significant, decrease in gemifloxacin exposure [AUC (0-inf) decreased 21% and Cmax decreased].

Sucralfate: When sucralfate (2 g) was administered 3 hours prior to gemifloxacin, the oral bioavailability of gemifloxacin was significantly reduced (53% decrease in AUC; 69% decrease in Cmax). When sucralfate (2 g) was administered 2 hours after gemifloxacin, the oral bioavailability of gemifloxacin was not significantly affected; therefore FACTIVE should be taken at least 2 hours before sucralfate. (See PRECAUTIONS.)

In vitro Metabolism: Results of in vitro inhibition studies indicate that hepatic cytochrome P450 (CYP450) enzymes do not play an important role in gemifloxacin metabolism. Therefore gemifloxacin should not cause significant in vivo pharmacokinetic interactions with other drugs that are metabolized by CYP450 enzymes.

Theophylline: Gemifloxacin 320 mg at steady-state did not affect the repeat dose pharmacokinetics of theophylline (300 to 400 mg BID to healthy male subjects).

Digoxin: Gemifloxacin 320 mg at steady-state did not affect the repeat dose pharmacokinetics of digoxin (0.25 mg once daily to healthy elderly subjects).

Oral Contraceptives: The effect of an oral estrogen/progesterone contraceptive product (once daily for 21 days) on the pharmacokinetics of gemifloxacin (320 mg once daily for 6 days) in healthy female subjects indicates that concomitant administration caused an average reduction in gemifloxacin AUC and Cmax of 19% and 12%. These changes are not considered clinically significant. Gemifloxacin 320 mg at steady-state did not affect the repeat dose pharmacokinetics of an ethinylestradiol/levonorgestrol oral contraceptive product (30 μg/150 μg once daily for 21 days to healthy female subjects).

Cimetidine: Co-administration of a single dose of 320 mg gemifloxacin with cimetidine 400 mg four times daily for 7 days resulted in slight average increases in gemifloxacin AUC(0-inf) and Cmax of 10% and 6%, respectively. These increases are not considered clinically significant.

Omeprazole: Co-administration of a single dose of 320 mg gemifloxacin with omeprazole 40 mg once daily for 4 days resulted in slight average increases in gemifloxacin AUC(0-inf) and Cmax of 10% and 11%, respectively. These increases are not considered clinically significant.

Warfarin: Administration of repeated doses of gemifloxacin (320 mg once daily for 7 days) to healthy subjects on stable warfarin therapy had no significant effect on warfarin-induced anticoagulant activity (i.e., International Normalized Ratios for Prothrombin Time). (See PRECAUTIONS: DRUG INTERACTIONS.)

Probenecid: Administration of a single dose of 320 mg gemifloxacin to healthy subjects who also received repeat doses of probenecid (total dose = 4.5 g) reduced the mean renal clearance of gemifloxacin by approximately 50%, resulting in a mean increase of 45% in gemifloxacin AUC (0-inf) and a prolongation of mean half-life by 1.6 hours. Mean gemifloxacin Cmax increased 8%.

Microbiology

Gemifloxacin has in vitro activity against a wide range of Gram-negative and Gram-positive microorganisms. Gemifloxacin is bactericidal with minimum bactericidal concentrations (MBCs) generally within one dilution of the minimum inhibitory concentrations (MICs). Gemifloxacin acts by inhibiting DNA synthesis through the inhibition of both DNA gyrase and topoisomerase IV (TOPO IV), which are essential for bacterial growth. Streptococcus pneumoniae showing mutations in both DNA gyrase and TOPO IV (double mutants) are resistant to most fluoroquinolones. Gemifloxacin has the ability to inhibit both enzyme systems at therapeutically relevant drug levels in S. pneumoniae (dual targeting), and has MIC values that are still in the susceptible range for some of these double mutants. However, the presence of double mutants was not evaluated in clinical trials; therefore, the clinical significance of these in vitro data are unknown.

The mechanism of action of quinolones, including gemifloxacin, is different from that of macrolides, beta-lactams, aminoglycosides, or tetracyclines; therefore, microorganisms resistant to these classes of drugs may be susceptible to gemifloxacin and other quinolones. There is no known cross-resistance between gemifloxacin and the above mentioned classes of antimicrobials.

The main mechanism of fluoroquinolone resistance is due to mutations in DNA gyrase and/or TOPO IV. Resistance to gemifloxacin develops slowly via multistep mutations and efflux in a manner similar to other fluoroquinolones. The frequency of spontaneous mutation is low (10-7 to <10-10). Although cross-resistance has been observed between gemifloxacin and other fluoroquinolones, some microorganisms resistant to other fluoroquinolones may be susceptible to gemifloxacin.

Gemifloxacin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section.

Aerobic Gram-positive microorganisms

Streptococcus pneumoniae (including multi-drug resistant strains [MDRSP])*

*MDRSP: multi-drug resistant Streptococcus pneumoniae, includes isolates previously known as PRSP (penicillin-resistant Streptococcus pneumoniae), and are strains resistant to two or more of the following antibiotics: penicillin (MIC ≥2 μg/mL), 2nd generation cephalosporins (e.g., cefuroxime), macrolides, tetracyclines and trimethoprim/sulfamethoxazole.

Aerobic Gram-negative microorganisms

Haemophilus influenzae
Haemophilus parainfluenzae

Klebsiella pneumoniae
(many strains are only moderately susceptible)
Moraxella catarrhalis

Other microorganisms

Chlamydia pneumoniae
Mycoplasma pneumoniae

The following data are available, but their clinical significance is unknown.

Gemifloxacin exhibits in vitro minimal inhibitory concentrations (MICs) of 0.25 μg/mL or less against most (≥90%) strains of the following microorganisms; however, the safety and effectiveness of gemifloxacin in treating clinical infections due to these microorganisms has not been established in adequate and well-controlled clinical trials:

Aerobic Gram-positive microorganisms

Staphylococcus aureus (methicillin-susceptible strains only)
Streptococcus pyogenes

Aerobic Gram-negative microorganisms

Acinetobacter lwoffii
Klebsiella oxytoca

Legionella pneumophila

Proteus vulgaris

Susceptibility Tests

Dilution techniques: Quantitative methods are used to determine antimicrobial minimum inhibitory concentrations (MICs). These MICs provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MICs should be determined using a standardized procedure. Standardized procedures are based on a dilution method1 (broth or agar) or equivalent with standardized inoculum concentrations and standardized concentrations of gemifloxacin powder. The MICs should be interpreted according to the following criteria:

For testing Klebsiella pneumoniae:

MIC (ug/mL) Interpretation
≤0.25 Susceptible (S)
0.5 Intermediate (I)
≥1.0 Resistant (R)

For testing Haemophilus influenzae and Haemophilus parainfluenzaea:

MIC (ug/mL) Interpretation
≤0.12 Susceptible (S)

a This interpretive standard is applicable only to broth microdilution susceptibility testing with Haemophilus influenzae and Haemophilus parainfluenzae using Haemophilus Test Medium (HTM)1.

The current absence of data on resistant strains precludes defining any results other than “Susceptible”. Strains yielding MIC results suggestive of a “nonsusceptible” category should be submitted to a reference laboratory for further testing.

For testing Streptococcus pneumoniaeb:

MIC (ug/mL) Interpretation
≤0.12 Susceptible (S)
0.25 Intermediate (I)
≥0.5 Resistant (R)

b These interpretive standards are applicable only to broth microdilution susceptibility tests using cation-adjusted Mueller-Hinton broth with 2-5% lysed horse blood.

A report of “Susceptible” indicates that the pathogen is likely to be inhibited if the antimicrobial compound in the blood reaches the concentration usually achievable. A report of “Intermediate” indicates that the result should be considered equivocal, and if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where high dosage of drug can be used. This category also provides a buffer zone, which prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of “Resistant” indicates that the pathogen is not likely to be inhibited if the antimicrobial compound in the blood reaches the concentration usually achievable; other therapy should be selected.

Standardized susceptibility test procedures require the use of laboratory control microorganisms to control the technical aspects of the laboratory procedures. Standard gemifloxacin powder should provide the following MIC values:

Microoraanism   MIC Ranae (ua/mL)
Escherichia coli ATCC 25922 0.004-0.016
Haemophilus influenzae ATCC 49247 0.002-0.008c
Streptococcus pneumoniae ATCC 49619 0.008-0.03d
c This quality control range is applicable to only H. influenzae ATCC 49247 tested by a broth microdilution procedure using Haemophilus Test Medium (HTM)1.
d This quality control range is applicable to only S. pneumoniae ATCC 49619 tested by a broth microdilution procedure using cation-adjusted Mueller-Hinton broth with 2-5% lysed horse blood.

Diffusion Techniques: Quantitative methods that require measurement of zone diameters also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. One such standardized procedure2 requires the use of standardized inoculum concentrations. This procedure uses paper disks impregnated with 5 μg gemifloxacin to test the susceptibility of microorganisms to gemifloxacin.

Reports from the laboratory providing results of the standard single-disk susceptibility test with a 5 μg gemifloxacin disk should be interpreted according to the following criteria:

For testing Klebsiella pneumoniae:

Zone Diameter (mm) Interpretation
≤20 Susceptible (S)
16-19 Intermediate (I)
≤15 Resistant (R)

For testing Haemophilus influenzae and Haemophilus parainfluenzaee:

Zone Diameter (mm) Interpretation
≥18 Susceptible (S)

eThis interpretive standard is applicable only to disk diffusion susceptibility testing with Haemophilus influenzae and Haemophilus parainfluenzae using Haemophilus Test Medium (HTM).2

The current absence of data on resistant strains precludes defining any results other than “Susceptible”. Strains yielding zone diameter results suggestive of a “nonsusceptible” category should be submitted to a reference laboratory for further testing.

For testing Streptococcus pneumoniaef:

Zone Diameter (mm) Interpretation
≥23 Susceptible (S)
20-22 Intermediate (I)
≤19 Resistant (R)

fThese zone diameter standards apply only to tests performed using Mueller-Hinton agar supplemented with 5% defibrinated sheep blood incubated in 5% CO2.

Interpretation should be as stated above for results using dilution techniques. Interpretation involves correlation of the diameter obtained in the disk test with the MIC for gemifloxacin.

As with standardized dilution techniques, diffusion methods require the use of laboratory control microorganisms that are used to control the technical aspects of the laboratory procedures. For the diffusion technique, the 5 μg gemifloxacin disk should provide the following zone diameters in these laboratory quality control strains:

Microoraanism   Zone Diameter (mm)
Escherichia coli ATCC 25922 29-36
Haemophilus influenzae ATCC 49247 30-37g
Streptococcus pneumoniae ATCC 49619 28-34h
g This quality control range is applicable to only H. influenzae ATCC 49247 tested by a disk diffusion procedure using Haemophilus Test Medium (HTM)2.
h This quality control range is applicable to only S. pneumoniae ATCC 49619 tested by a disk diffusion procedure using Mueller-Hinton agar supplemented with 5% defibrinated sheep blood and incubated in 5% CO2.

Animal Pharmacology

Quinolones have been shown to cause arthropathy in immature animals. Degeneration of articular cartilage occurred in juvenile dogs given at least 192 mg/kg/day gemifloxacin in a 28day study (producing about 6 times the systemic exposure at the clinical dose), but not in mature dogs. There was no damage to the articular surfaces of joints in immature rats given repeated doses of up to 800 mg/kg/day.

Some quinolones have been reported to have proconvulsant properties that are potentiated by the concomitant administration of non-steroidal anti-inflammatory drugs (NSAIDs). Gemifloxacin alone had effects in tests of behavior or CNS interaction typically at doses of at least 160 mg/kg. No convulsions occurred in mice given the active metabolite of the NSAID, fenbufen, followed by 80 mg/kg gemifloxacin.

Dogs given 192 mg/kg/day (about 6 times the systemic exposure at the clinical dose) for 28 days, or 24 mg/kg/day (approximately equivalent to the systemic exposure at the clinical dose) for 13 weeks showed reversible increases in plasma ALT activities and local periportal liver changes associated with blockage of small bile ducts by crystals containing gemifloxacin.

Quinolones have been associated with prolongation of the electrocardiographic QT interval in dogs. Gemifloxacin produced no effect on the QT interval in dogs dosed orally to provide about 4 times human therapeutic plasma concentrations at Cmax, and transient prolongation after intravenous administration at more than 4 times human plasma levels at Cmax. Gemifloxacin exhibited weak activity in the cardiac IKr (hERG) channel inhibition assay, having an IC50 of approximately 270 μM.

Gemifloxacin, like many other quinolones, tends to crystallize at the alkaline pH of rodent urine, resulting in a nephropathy in rats that is reversible on drug withdrawal (oral no-effect dose 24 mg/kg/day).

Gemifloxacin was weakly phototoxic to hairless mice given a single 200 mg/kg oral dose and exposed to UVA radiation. However, no evidence of phototoxicity was observed at 100 mg/kg/day dosed orally for 13 weeks in a standard hairless mouse model, using simulated sunlight.

Clinical Studies

Acute Bacterial Exacerbation of Chronic Bronchitis (ABECB)

FACTIVE (320 mg once daily for 5 days) was evaluated for the treatment of acute bacterial exacerbation of chronic bronchitis in three pivotal double-blind, randomized, actively-controlled clinical trials (studies 068, 070, and 212). The primary efficacy parameter in these studies was the clinical response at follow-up (day 13 to 24). The results of the clinical response at follow-up for the principal ABECB studies demonstrate that FACTIVE 320 mg PO once daily for 5 days was at least as good as the comparators given for 7 days. The results are shown in Table 6 below.

Table 6: Clinical Response at Follow-Up (Test of Cure): Pivotal ABECB Studies

Drug Regimen Success Rate % (n/N) Treatment Difference (95% CI)
Study 068
  FACTIVE 320 mg x 5 days 86.0 (239/278) 1.2 (-4.7, 7.0)
  Clarithromycin 500 mg BID x 7 days 84.8 (240/283)
Study 070
  FACTIVE 320 mg x 5 days 93.6 (247/264) 0.4 (-3.9, 4.6)
  Amoxicillin/clavulanate 500 mg/125 mg TID x 7 days 93.2 (248/266)
Study 212
  FACTIVE 320 mg x 5 days 88.2 (134/152) 3.1 (-4.7, 10.7)
  Levofloxacin 500 mg x 7 days 85.1 (126/148)

Community Acquired Pneumonia (CAP)

5 Day Treatment Regimen

To evaluate the safety and efficacy of a 5-day course of FACTIVE, 510 outpatient and hospitalized adults with clinically and radiologically determined mild to moderate community-acquired pneumonia were clinically evaluated in a double-blind, randomized, prospective, multicenter study comparing FACTIVE 320 mg for five days to FACTIVE 320 mg for seven days (Study OP-634-001).

Clinical success rates in the clinically evaluable population were 95.0% in the 5 day group and 92.1% in the 7 day group.

Table 7: Clinical Response at Follow-Up (Test of Cure): Study OP-634-001

Drug Regimen Success Rate % (n/N) Treatment Difference (95% CI)
Study OP-634-001
  FACTIVE 320 mg x 5 days 95.0 (230/242) 3.0 (-1.5, 7.4)
  FACTIVE 320 mg x 7 days 92.1 (209/227)

The microbiological efficacy of the 5-day regimen was documented for pathogens listed in Table 8 below.

Table 8: Bacterial Eradication by Pathogen for Patients Treated with FACTIVE in Study OP-634-001

Pathogen 5-day 7-day
n/N % n/N %
Streptococcus pneumoniae 26/26 100 34/40 85
Mycoplasma pneumoniae 22/25 88 19/20 95
Haemophilus influenzae 21/22 95.5 18/18 100
Chlamydia pneumoniae 17/18 94.4 30/31 96.8

7 Day Treatment Regimen

Previous clinical studies evaluated the efficacy of FACTIVE in a 7-day treatment of CAP in adults. This clinical program consisted of three double-blind, randomized, actively-controlled clinical studies (studies 011, 012, and 049) and one open-label, actively-controlled study (study 185). In addition, two uncontrolled studies (studies 061 and 287) were conducted. Three of the studies, controlled study 011 and the uncontrolled studies, had a fixed 7-day duration of treatment for FACTIVE. Controlled study 011 compared a 7-day course of FACTIVE with a 10day treatment course of amoxicillin/clavulanate (1g/125 mg TID) and clinical success rates were similar between treatment arms. The results of comparative studies 049, 185, and 012 were supportive although treatment duration could have been 7 to 14 days. The results of the clinical studies with a fixed 7-day duration of FACTIVE are shown in Table 9.

Table 9: Clinical Response at Follow-Up (Test of Cure): CAP Studies with a Fixed 7-day Duration of Treatment

Drug Regimen Success Rate %
(n/N)
Treatment Difference (95% CI)*
Study 011
  FACTIVE 320 mg x 7 days 88.7 (102/115) 1.1 (-7.3, 9.5)
  Amoxicillin/clavulanate 1 g/125 mg TID x 10 days 87.6 (99/113)
Study 061
  FACTIVE 320 mg x 7 days 91.7 (154/168) (86.1, 95.2)
Study 287
  FACTIVE 320 mg x 7 days 89.8 (132/147) (84.9, 94.7)
*For uncontrolled studies, the 95% CI around the success rate is shown

The combined bacterial eradication rates for patients treated with a fixed 7-day treatment regimen of FACTIVE are shown in Table 10.

Table 10:Bacterial Eradication by Pathogen for Patients Treated with FACTIVE in Studieswith a Fixed 7-day Duration of Treatment

Pathogen n/N %
S. pneumoniae 102/117 87.2
M. pneumoniae 40/42 95.2
H. influenzae 48/53 90.6
C. pneumoniae 43/45 95.6
K. pneumoniae 18/20 90
M. catarrhalis 12-Nov 91.7

7 Day Treatment Regimen of Community-Acquired Pneumonia Due to Multi-Drug Resistant Streptococcus pneumoniae (MDRSP)

FACTIVE was also effective in the treatment of CAP due to multi-drug resistant Streptococcus pneumoniae (MDRSP*). Of 35 patients with MDRSP treated for 7 days, 29 (82.9%) achieved clinical and bacteriological success at follow-up. The clinical and bacteriological success for the 35 patients with MDRSP isolates are shown in Table 11.

*MDRSP: multi-drug resistant Streptococcus pneumoniae, includes isolates previously known as PRSP (penicillin-resistant Streptococcus pneumoniae), and are strains resistant to two or more of the following antibiotics: penicillin (MIC ≥2 μg/mL), 2nd generation cephalosporins (e.g., cefuroxime), macrolides, tetracyclines and trimethoprim/sulfamethoxazole.

Table 11: Clinical and Bacteriological Success for 35 Patients Treated with FACTIVE inCAP Studies with a 7-day Duration of Treatment for MDRSP

Screening Susceptibility Clinical Success Bacteriological Success
n/Na % n/Nb %
Penicillin-resistant 15/16 93.8 15/16 93.8
2nd generation cephalosporin-resistant 20/22 90.9 20/22 90.9
Macrolide-resistantc 24/28 85.7 23/28 82.1
Trimethoprim/sulfamethoxazole-resistant 23/26 88.5 23/26 88.5
Tetracycline-resistant 21/27 77.8 20/27 74.1
an = the number of patients successfully treated; N = number of patients with MDRSP
bn = the number of bacteriological isolates successfully treated; N = number of isolates studied
cMacrolide antibiotics tested include clarithromycin and erythromycin

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

Table 12:Resistant Streptococcus pneumoniae Clinical Success and Bacteriological Eradication Rates

S. pneumoniae with MDRSP Clinical Cure Rate Bacteriological Eradication Rate
n/N % n/N %
Resistant to 2 antimicrobials 8/11 72.7 7/11 63.6
Resistant to 3 antimicrobials 5/7 71.4 5/7 71.4
Resistant to 4 antimicrobials 8/9 88.9 8/9 88.9
Resistant to 5 antimicrobials 8/8 100 8/8 100
Bacteremia with MDRSP 3/3 100 3/3 100

Clinical Safety Study of Rash

To further characterize gemifloxacin-associated rash, which in early clinical studies appeared to be associated with age less than 40 and female gender, a clinical pharmacology study was conducted. The study enrolled 1,011 healthy female volunteers less than 40 years of age. Subjects were randomized in a 5:1 ratio to receive either FACTIVE 320 mg PO daily (819 subjects) or ciprofloxacin 500 mg PO twice daily for 10 days (164 subjects). This study was designed to enroll subjects at a high risk for rash (women <40 years of age and dosing beyond the recommended duration of therapy for FACTIVE [10 days]) and over estimates the risk to patients taking FACTIVE as prescribed. Subjects who received FACTIVE were 7 times more likely to develop rash than those who received ciprofloxacin. Of the 260 rashes in subjects receiving FACTIVE, the majority of rashes were maculopapular and of mild to moderate severity; 7% of the rashes were reported as severe, and severity appeared to correlate with the extent of the rash. In 68% of the subjects reporting a severe rash and approximately 25% of all those reporting rash, >60% of the body surface area was involved; the characteristics of the rash were otherwise indistinguishable from those subjects reporting a mild rash. The histopathology was consistent with the clinical observation of uncomplicated exanthematous morbilliform eruption. Approximately 11% of the rashes were described as being “urticaria-like”. There were no documented cases of hypersensitivity syndrome or findings suggestive of angioedema or other serious cutaneous reactions.

The majority of rashes (81.9%) occurred on days 8 through 10 of the planned 10 day course of FACTIVE; 2.7% of rash events occurred within one day of the start of dosing. The median duration of rash was 6 days. The rash resolved without treatment in the majority of subjects. Approximately 19% received antihistamines and 5% received steroids, although the therapeutic benefit of these therapies is uncertain.

In the second part of this study after a 4 to 6 week wash out period, subjects developing a rash on FACTIVE were treated with ciprofloxacin (n=136) or placebo (n=50); 5.9% developed rash when treated with ciprofloxacin and 2.0% developed rash when treated with placebo. The cross sensitization rate to other fluoroquinolones was not evaluated in this clinical study. There was no evidence of sub-clinical sensitization to FACTIVE on a second exposure (i.e., subjects who had not developed a rash to FACTIVE in the first part of the study were not at higher risk of developing a rash to FACTIVE with a second exposure).

There was no relationship between the incidence of rash and systemic exposure (Cmax and AUC) to either gemifloxacin or its major metabolite, N-acetyl gemifloxacin.

REFERENCES

1. Clinical and Laboratory Standards Institute. Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically-Seventh Edition. Clinical and Laboratory Standards Institute document M7-A7, Vol. 26, No. 2, CLSI, Wayne, PA, January 2006.

2. Clinical and Laboratory Standards Institute. Performance Standards for Antimicrobial Disk Susceptibility Tests-Ninth Edition. Clinical and Laboratory Standards Institute document m²-A9, Vol. 26, No. 1, CLSI, Wayne, PA, January 2006.

Last reviewed on RxList: 8/28/2013
This monograph has been modified to include the generic and brand name in many instances.

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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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