CLINICAL PHARMACOLOGY
Mechanism Of Action
Tigecycline is a tetracycline
class antibacterial [see Microbiology].
Pharmacodynamics
Cardiac Electrophysiology
No significant effect of a
single intravenous dose of tigecycline 50 mg or 200 mg on QTc interval was detected in a randomized, placebo-and
active-controlled four-arm crossover thorough QTc study of 46 healthy subjects.
Pharmacokinetics
The mean pharmacokinetic
parameters of tigecycline after single and multiple intravenous doses based on
pooled data from clinical pharmacology studies are summarized in Table 3.
Intravenous infusions of tigecycline were administered over approximately 30 to
60 minutes.
Table 3: Mean (CV%) Pharmacokinetic
Parameters of Tigecycline
|
Single Dose 100 mg
(N=224) |
Multiple Dosea 50 mg every 12h
(N=103) |
Cmax (mcg/mL)b |
1.45 (22%) |
0.87 (27%) |
Cmax (mcg/mL)c |
0.90 (30%) |
0.63 (15%) |
AUC (mcg•h/mL) |
5.19 (36%) |
-- |
AUC0-24h (mcg•h/mL) |
- - |
4.7 (36%) |
Cmin (mcg/mL) |
- - |
0.13 (59%) |
t½ (h) |
27.1 (53%) |
42.4 (83%) |
CL (L/h) |
21.8 (40%) |
23.8 (33%) |
CLr (mL/min) |
38.0 (82%) |
51.0 (58%) |
Vss (L) |
568 (43%) |
639 (48%) |
a 100 mg initially, followed by 50 mg every 12
hours
b 30-minute infusion
c 60-minute infusion |
Distribution
The in vitro plasma protein
binding of tigecycline ranges from approximately 71% to 89% at concentrations
observed in clinical studies (0.1 to 1.0 mcg/mL). The steady-state volume of
distribution of tigecycline averaged 500 to 700 L (7 to 9 L/kg), indicating
tigecycline is extensively distributed beyond the plasma volume and into the
tissues.
Following the administration of
tigecycline 100 mg followed by 50 mg every 12 hours to 33 healthy volunteers,
the tigecycline AUC0-12h (134 mcg•h/mL) in alveolar cells was approximately
78-fold higher than the AUC0-12h in the serum, and the AUC0-12h (2.28 mcg•h/mL)
in epithelial lining fluid was approximately 32% higher than the AUC0-12h in
serum. The AUC0-12h (1.61 mcg•h/mL) of tigecycline in skin blister fluid was
approximately 26% lower than the AUC0-12h in the serum of 10 healthy subjects.
In a single-dose study,
tigecycline 100 mg was administered to subjects prior to undergoing elective
surgery or medical procedure for tissue extraction. Concentrations at 4 hours
after tigecycline administration were higher in gallbladder (38-fold, n=6),
lung (3.7-fold, n=5), and colon (2.3-fold, n=6), and lower in synovial
fluid (0.58-fold, n=5), and bone (0.35-fold, n=6) relative to serum. The
concentration of tigecycline in these tissues after multiple doses has not been
studied.
Elimination
Metabolism
Tigecycline is not extensively metabolized. In vitro studies
with tigecycline using human liver microsomes, liver slices, and hepatocytes
led to the formation of only trace amounts of metabolites. In healthy male
volunteers receiving 14C-tigecycline, tigecycline was the primary 14C-labeled
material recovered in urine and feces, but a glucuronide, an N-acetyl
metabolite, and a tigecycline epimer (each at no more than 10% of the
administered dose) were also present.
Excretion
The recovery of total radioactivity in feces and urine
following administration of 14C -tigecycline indicates that 59% of
the dose is eliminated by biliary/fecal excretion, and 33% is excreted in
urine. Approximately 22% of the total dose is excreted as unchanged tigecycline
in urine. Overall, the primary route of elimination for tigecycline is biliary
excretion of unchanged tigecycline and its metabolites. Glucuronidation and
renal excretion of unchanged tigecycline are secondary routes.
Specific Populations
Hepatic Impairment
In a study comparing 10 patients with mild hepatic
impairment (Child Pugh A), 10 patients with moderate hepatic impairment (Child
Pugh B), and 5 patients with severe hepatic impairment (Child Pugh C) to 23 age
and weight matched healthy control subjects, the single-dose pharmacokinetic
disposition of tigecycline was not altered in patients with mild hepatic
impairment. However, systemic clearance of tigecycline was reduced by 25% and
the half-life of tigecycline was prolonged by 23% in patients with moderate
hepatic impairment (Child Pugh B). Systemic clearance of tigecycline was
reduced by 55%, and the half-life of tigecycline was prolonged by 43% in
patients with severe hepatic impairment (Child Pugh C). Dosage adjustment is
necessary in patients with severe hepatic impairment (Child Pugh C) [see Use
in Specific Populations and DOSAGE AND ADMINISTRATION].
Renal Impairment
A single dose study compared 6 subjects with severe renal
impairment (creatinine clearance < 30 mL/min), 4 end stage renal disease
(ESRD) patients receiving tigecycline 2 hours before hemodialysis, 4 ESRD
patients receiving tigecycline 1 hour after hemodialysis, and 6 healthy control
subjects. The pharmacokinetic profile of tigecycline was not significantly
altered in any of the renally impaired patient groups, nor was tigecycline removed
by hemodialysis. No dosage adjustment of tigecycline is necessary in patients
with renal impairment or in patients undergoing hemodialysis.
Geriatric Patients
No significant differences in pharmacokinetics were
observed between healthy elderly subjects (n=15, age 65 to 75; n=13, age >
75) and younger subjects (n=18) receiving a single 100 mg dose of tigecycline.
Therefore, no dosage adjustment is necessary based on age [see Use in
Specific Populations].
Pediatric Patients
A single-dose safety, tolerability, and pharmacokinetic
study of tigecycline in pediatric patients aged 8 to 16 years who recently
recovered from infections was conducted. The doses administered were 0.5, 1, or
2 mg/kg. The study showed that for children aged 12 to 16 years (n = 16) a
dosage of 50 mg twice daily would likely result in exposures comparable to
those observed in adults with the approved dosing regimen. Large variability
observed in children aged 8 to 11 years of age (n = 8) required additional
study to determine the appropriate dosage.
A subsequent tigecycline dose-finding study was conducted
in 8 to 11 year old patients with cIAI, cSSSI, or CABP. The doses of
tigecycline studied were 0.75 mg/kg (n = 17), 1 mg/kg (n = 21), and 1.25 mg/kg
(n=20). This study showed that for children aged 8 to 11 years, a 1.2 mg/kg
dose would likely result in exposures comparable to those observed in adults
resulting with the approved dosing regimen [see DOSAGE AND ADMINISTRATION].
Gender
In a pooled analysis of 38 women and 298 men
participating in clinical pharmacology studies, there was no significant
difference in the mean (± SD) tigecycline clearance between women (20.7 ± 6.5
L/h) and men (22.8 ± 8.7 L/h). Therefore, no dosage adjustment is necessary
based on gender.
Race
In a pooled analysis of 73 Asian subjects, 53 Black
subjects, 15 Hispanic subjects, 190 White subjects, and 3 subjects classified
as “other” participating in clinical pharmacology studies, there was no
significant difference in the mean (± SD) tigecycline clearance among the Asian
subjects (28.8 ± 8.8 L/h), Black subjects (23 ± 7.8 L/h), Hispanic subjects
(24.3 ± 6.5 L/h), White subjects (22.1 ± 8.9 L/h), and “other”
subjects (25 ± 4.8 L/h). Therefore, no dosage adjustment is necessary based on
race.
Drug Interaction Studies
Digoxin
Tigecycline (100 mg followed by 50 mg every 12 hours) and
digoxin (0.5 mg followed by 0.25 mg, orally, every 24 hours) were
co-administered to healthy subjects in a drug interaction study. Tigecycline
slightly decreased the Cmax of digoxin by 13%, but did not affect the AUC or
clearance of digoxin. This small change in Cmax did not affect the steady-state
pharmacodynamic effects of digoxin as measured by changes in ECG intervals. In
addition, digoxin did not affect the pharmacokinetic profile of tigecycline.
Therefore, no dosage adjustment of either drug is necessary when tigecycline is
administered with digoxin.
Warfarin
Concomitant administration of tigecycline (100 mg
followed by 50 mg every 12 hours) and warfarin (25 mg single-dose) to healthy
subjects resulted in a decrease in clearance of R-warfarin and S-warfarin by
40% and 23%, an increase in Cmax by 38% and 43% and an increase in AUC by 68%
and 29%, respectively. Tigecycline did not significantly alter the effects of
warfarin on INR. In addition, warfarin did not affect the pharmacokinetic
profile of tigecycline. However, prothrombin time or other suitable anticoagulation
test should be monitored if tigecycline is administered with warfarin.
In vitro studies in human liver microsomes indicate that
tigecycline does not inhibit metabolism mediated by any of the following 6
cytochrome P450 (CYP) isoforms: 1A2, 2C8, 2C9, 2C19, 2D6, and 3A4. Therefore,
tigecycline is not expected to alter the metabolism of drugs metabolized by
these enzymes. In addition, because tigecycline is not extensively metabolized,
clearance of tigecycline is not expected to be affected by drugs that inhibit
or induce the activity of these CYP450 isoforms.
Microbiology
Mechanism Of Action
Tigecycline inhibits protein translation in bacteria by
binding to the 30S ribosomal subunit and blocking entry of amino-acyl tRNA
molecules into the A site of the ribosome. This prevents incorporation of amino
acid residues into elongating peptide chains. In general, tigecycline is
considered bacteriostatic; however, tigecycline has demonstrated bactericidal
activity against isolates of S. pneumoniae and L. pneumophila.
Resistance
To date there has been no cross-resistance observed
between tigecycline and other antibacterials. Tigecycline is less affected by
the two major tetracycline-resistance mechanisms, ribosomal protection and efflux.
Additionally, tigecycline is not affected by resistance mechanisms such as
beta-lactamases (including extended spectrum betalactamases), target-site
modifications, macrolide efflux pumps or enzyme target changes (e.g.
gyrase/topoisomerases). However, some ESBL-producing isolates may confer
resistance to tigecycline via other resistance mechanisms. Tigecycline
resistance in some bacteria (e.g. Acinetobacter calcoaceticus-Acinetobacter
baumannii complex) is associated with multi-drug resistant (MDR) efflux pumps.
Interaction With Other Antimicrobials
In vitro studies have not demonstrated antagonism between
tigecycline and other commonly used antibacterials.
Antimicrobial Activity
Tigecycline has been shown to be active against most of
the following bacteria, both in vitro and in clinical infections [see
INDICATIONS AND USAGE].
Gram-positive Bacteria
Enterococcus faecalis (vancomycin-susceptible
isolates)
Staphylococcus aureus (methicillin-susceptible and
-resistant isolates)
Streptococcus agalactiae
Streptococcus anginosus group (includes S.
anginosus, S. intermedius, and S. constellatus)
Streptococcus pneumoniae (penicillin-susceptible
isolates) Streptococcus pyogenes
Gram-negative Bacteria
Citrobacter freundii
Enterobacter cloacae
Escherichia coli
Haemophilus influenza
Klebsiella oxytoca
Klebsiella pneumonia
Legionella pneumophila
Anaerobic Bacteria
Bacteroides fragilis
Bacteroides thetaiotaomicron
Bacteroides uniformis
Bacteroides vulgates
Clostridium perfringens
Peptostreptococcus micros
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 concentration (MIC) less than or equal
to the susceptible breakpoint for tigecycline against isolates of similar genus
or organism group. However, the efficacy of tigecycline in treating clinical
infections due to these bacteria has not been established in adequate and
well-controlled clinical trials.
Gram-positive Bacteria
Enterococcus avium
Enterococcus casseliflavus
Enterococcus faecalis (vancomycin-resistant
isolates)
Enterococcus faecium (vancomycin-susceptible and
-resistant isolates)
Enterococcus gallinarum
Listeria monocytogenes
Staphylococcus epidermidis (methicillin-susceptible
and -resistant isolates)
Staphylococcus haemolyticus
Gram-negative Bacteria
Acinetobacter baumannii*
Aeromonas hydrophila
Citrobacter koseri
Enterobacter aerogenes
Haemophilus influenzae (ampicillin-resistant)
Haemophilus parainfluenzae
Pasteurella multocida
Serratia marcescens
Stenotrophomonas maltophilia
Anaerobic Bacteria
Bacteroides distasonis
Bacteroides ovatus
Peptostreptococcus spp.
Porphyromonas spp.
Prevotella spp.
Other Bacteria
Mycobacterium abscessus
Mycobacterium fortuitum
*There have been reports of the development of
tigecycline resistance in Acinetobacter infections seen during the course of
standard treatment. Such resistance appears to be attributable to an MDR efflux
pump mechanism. While monitoring for relapse of infection is important for all
infected patients, more frequent monitoring in this case is suggested. If
relapse is suspected, blood and other specimens should be obtained and cultured
for the presence of bacteria. All bacterial isolates should be identified and
tested for susceptibility to tigecycline and other appropriate antimicrobials.
Susceptibility Test Methods
When available, the clinical microbiology laboratory
should provide cumulative results of the in vitro susceptibility test results
for antimicrobial drugs used in local hospitals and practice areas to the
physician as periodic reports that describe the susceptibility profile of
nosocomial and community-acquired pathogens. These reports should aid the
physician in selecting an antibacterial drug for treatment.
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 test method (broth, and/or
agar, or microdilution)1,3,4. For broth dilution tests for aerobic
organisms, MICs must be determined in testing medium that is fresh ( < 12h
old). The MIC values should be interpreted according to the criteria provided
in Table 4.
Diffusion Techniques
Quantitative methods that require measurement of zone
diameters also provide reproducible estimates of the susceptibility of bacteria
to antimicrobial compounds. The zone size should be determined using a
standardized test method2,4. This procedure uses paper disks
impregnated with 15 mcg tigecycline to test the susceptibility of bacteria to
tigecycline. The disc diffusion breakpoints are noted in Table 4.
Anaerobic Techniques
Anaerobic susceptibility testing with tigecycline should
be done by the agar dilution method3,4 since quality control
parameters for broth-dilution are not established.
Table 4: Susceptibility Test Result Interpretive
Criteria for Tigecycline
Pathogen |
Minimum Inhibitory Concentrations (mcg/mL) |
Disk Diffusion (zone diameters in mm) |
S |
I |
R |
S |
I |
R |
Staphylococcus aureus (including methicillin-resistant isolates) |
≤ 0.5a |
- |
- |
≥ 19 |
- |
- |
Streptococcus spp. other than S. pneumoniae |
≤ 0.25a |
- |
- |
≥ 19 |
- |
- |
Streptococcus pneumoniae |
≤ 0.06a |
- |
- |
≥ 19 |
- |
- |
Enterococcus faecalis (vancomycin-susceptible isolates) |
≤ 0.25a |
- |
- |
≥ 19 |
- |
- |
Enterobacteriaceaeb |
≤ 2 |
4 |
≥ 8 |
≥ 19 |
15 to 18 |
≤ 14 |
Haemophilus influenzae |
≤ 0.25a |
- |
- |
≥ 19 |
- |
- |
Anaerobesc |
≤ 4 |
8 |
≥ 16 |
n/a |
n/a |
n/a |
a The current absence of resistant isolates
precludes defining any results other than “Susceptible.” Isolates yielding MIC
results suggestive of “Nonsusceptible” category should be submitted to
reference laboratory for further testing.
b Tigecycline has decreased in vitro activity against Morganella spp.,
Proteus spp. and Providencia spp.
c Agar dilution |
A report of “Susceptible”(S) indicates that the
antimicrobial drug is likely to inhibit growth of the pathogen if the
antimicrobial drug reaches the concentration usually achievable at the site of
infection. A report of “Intermediate”(I) 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 a high dosage of drug can be used. This category also provides a
buffer zone that prevents small uncontrolled technical factors from causing
major discrepancies in interpretation. A report of “Resistant”(R)
indicates that the antimicrobial drug is not likely to inhibit the growth of
the pathogen if the antimicrobial drug reaches the concentration usually
achievable; other therapy should be selected.
Quality Control
Standardized susceptibility test procedures require the
use of laboratory controls to monitor and ensure the accuracy and precision of
supplies and reagents used in the assay, and the techniques of the individuals
performing the test.1,2,3,4 Standard tigecycline powder should
provide the following range of MIC values noted in Table 5. For the diffusion technique using the 15 mcg tigecycline
disk, the criteria provided in Table 5 should be achieved.
Table 5: Acceptable Quality
Control Ranges for Tigecycline
QC Strain |
Minimum Inhibitory Concentrations (mcg/mL) |
Disk Diffusion (zone diameters in mm) |
Staphylococcus aureus ATCC 25923 |
Not Applicable |
20 to 25 |
Staphylococcus aureus ATCC 29213 |
0.03 to 0.25 |
Not Applicable |
Escherichia coli ATCC 25922 |
0.03 to 0.25 |
20 to 27 |
Enterococcus faecalis ATCC 29212 |
0.03 to 0.12 |
Not Applicable |
Streptococcus pneumoniae ATCC 49619 |
0.015 to 0.12 |
23 to 29 |
Haemophilus influenzae ATCC 49247 |
0.06 to 0.5 |
23 to 31 |
Neisseria gonorrhoeae ATCC 49226 |
Not Applicable |
30 to 40 |
Bacteroides fragilisa ATCC 25285 |
0.12 to 1 |
Not Applicable |
Bacteroides thetaiotaomicrona ATCC 29741 |
0.5 to 2 |
Not Applicable |
Eggerthella lentda ATCC 43055 |
0.06 to 0.5 |
Not Applicable |
Clostridium difficilea ATCC 70057 |
0.125 to 1 |
Not Applicable |
Pseudomonas aeruginosab ATCC 27853 |
Not Applicable |
9 to 13 |
ATCC = American Type Culture Collection
a Agar dilution
b Pseudomonas aeruginosa is included for quality control purpose
only |
Animal Toxicology And/Or
Pharmacology
In two week studies, decreased
erythrocytes, reticulocytes, leukocytes, and platelets, in association with
bone marrow hypocellularity, have been seen with tigecycline at exposures of 8
times and 10 times the human daily dose based on AUC in rats and dogs, (AUC of
approximately 50 and 60 mcg•hr/mL at doses of 30 and 12 mg/kg/day)
respectively. These alterations were shown to be reversible after two weeks of
dosing.
Clinical Studies
Complicated Skin And Skin
Structure Infections
Tigecycline was evaluated in
adults for the treatment of complicated skin and skin structure infections
(cSSSI) in two randomized, double-blind, active-controlled, multinational,
multicenter studies (Studies 300 and 305). These studies compared tigecycline
(100 mg intravenous initial dose followed by 50 mg every 12 hours) with
vancomycin (1 g intravenous every 12 hours)/aztreonam (2 g intravenous every 12
hours) for 5 to 14 days. Patients with complicated deep soft tissue infections
including wound infections and cellulitis ( ≥ 10 cm, requiring
surgery/drainage or with complicated underlying disease), major abscesses,
infected ulcers, and burns were enrolled in the studies. The primary efficacy
endpoint was the clinical response at the test of cure (TOC) visit in the
co-primary populations of the clinically evaluable (CE) and clinical modified
intent-to-treat (c-mITT) patients. See Table 6. Clinical cure rates at TOC by
pathogen in the microbiologically evaluable patients are presented in Table 7.
Table 6: Clinical Cure Rates from Two Studies in
Complicated Skin and Skin Structure Infections after 5 to 14 Days of Therapy
|
Tigecyclinea
n/N (%) |
Vancomycin/Aztreonamb
n/N (%) |
Study 300 |
CE |
165/199 (82.9) |
163/198 (82.3) |
c-mITT |
209/277 (75.5) |
200/260 (76.9) |
Study 305 |
CE |
200/223 (89.7) |
201/213 (94.4) |
c-mITT |
220/261 (84.3) |
225/259 (86.9) |
a 100 mg initially, followed by 50 mg every 12
hours
b Vancomycin (1 g every 12 hours)/Aztreonam (2 g every 12 hours) |
Table 7: Clinical Cure Rates by Infecting Pathogen in
Microbiologically Evaluable Patients with Complicated Skin and Skin Structure
Infectionsa
Pathogen |
Tigecycline
n/N (%) |
Vancomycin/Aztreonam
n/N (%) |
Escherichia coli |
29/36 (80.6) |
26/30 (86.7) |
Enterobacter cloacae |
10/12 (83.3) |
15/15 (100) |
Enterococcus faecalis (vancomycin-susceptible only) |
15/21 (71.4) |
19/24 (79.2) |
Klebsiella pneumoniae |
12/14 (85.7) |
15/16 (93.8) |
Methicillin-susceptible Staphylococcus aureus (MSSA) |
124/137 (90.5) |
113/120 (94.2) |
Methicillin-resistant Staphylococcus aureus (MRSA) |
79/95 (83.2) |
46/57 (80.7) |
Streptococcus agalactiae |
8/8 (100) |
11/14 (78.6) |
Streptococcus anginosus grpb |
17/21 (81.0) |
9/10 (90.0) |
Streptococcus pyogenes |
31/32 (96.9) |
24/27 (88.9) |
Bacteroides fragilis |
7/9 (77.8) |
4/5 (80.0) |
a Two cSSSI pivotal studies and two Resistant
Pathogen studies
b Includes Streptococcus anginosus, Streptococcus intermedius, and Streptococcus
constellatus |
Complicated Intra-abdominal
Infections
Tigecycline was evaluated in
adults for the treatment of complicated intra-abdominal infections (cIAI) in
two randomized, double-blind, active-controlled, multinational, multicenter
studies (Studies 301 and 306). These studies compared tigecycline (100 mg
intravenous initial dose followed by 50 mg every 12 hours) with
imipenem/cilastatin (500 mg intravenous every 6 hours) for 5 to 14 days. Patients
with complicated diagnoses including appendicitis, cholecystitis,
diverticulitis, gastric/duodenal perforation, intra-abdominal abscess,
perforation of intestine, and peritonitis were enrolled in the studies. The
primary efficacy endpoint was the clinical response at the TOC visit for the
co-primary populations of the microbiologically evaluable (ME) and the
microbiologic modified intent-to-treat (m-mITT) patients. See Table 8. Clinical
cure rates at TOC by pathogen in the microbiologically evaluable patients are
presented in Table 9.
Table 8: Clinical Cure Rates from Two Studies in
Complicated Intra-abdominal Infections after 5 to 14 Days of Therapy
|
Tigecyclinea
n/N (%) |
Imipenem/Cilastatinb
n/N (%) |
Study 301 |
ME |
199/247 (80.6) |
210/255 (82.4) |
m-mITT |
227/309 (73.5) |
244/312 (78.2) |
Study 306 |
ME |
242/265 (91.3) |
232/258 (89.9) |
m-mITT |
279/322 (86.6) |
270/319 (84.6) |
a 100 mg initially, followed by 50 mg every 12
hours
b Imipenem/Cilastatin (500 mg every 6 hours) |
Table 9: Clinical Cure Rates by Infecting Pathogen in
Microbiologically Evaluable Patients with Complicated Intra-abdominal
Infectionsa
Pathogen |
Tigecycline
n/N (%) |
Imipenem/Cilastatin
n/N (%) |
Citrobacter freundii |
12/16 (75.0) |
3/4 (75.0) |
Enterobacter cloacae |
15/17 (88.2) |
16/17 (94.1) |
Escherichia coli |
284/336 (84.5) |
297/342 (86.8) |
Klebsiella oxytoca |
19/20 (95.0) |
17/19 (89.5) |
Klebsiella pneumoniae |
42/47 (89.4) |
46/53 (86.8) |
Enterococcus faecalis |
29/38 (76.3) |
35/47 (74.5) |
Methicillin-susceptible Staphylococcus aureus (MSSA) |
26/28 (92.9) |
22/24 (91.7) |
Methicillin-resistant Staphylococcus aureus (MRSA) |
16/18 (88.9) |
1/3 (33.3) |
Streptococcus anginosus grpb |
101/119 (84.9) |
60/79 (75.9) |
Bacteroides fragilis |
68/88 (77.3) |
59/73 (80.8) |
Bacteroides thetaiotaomicron |
36/41 (87.8) |
31/36 (86.1) |
Bacteroides uniformis |
12/17 (70.6) |
14/16 (87.5) |
Bacteroides vulgatus |
14/16 (87.5) |
4/6 (66.7) |
Clostridium perfringens |
18/19 (94.7) |
20/22 (90.9) |
Peptostreptococcus micros |
13/17 (76.5) |
8/11 (72.7) |
a Two cIAI pivotal studies and two Resistant
Pathogen studies
b Includes Streptococcus anginosus, Streptococcus intermedius,
and Streptococcus constellatus |
Community-Acquired Bacterial
Pneumonia Tigecycline was evaluated in adults
for the treatment of community-acquired bacterial pneumonia (CABP) in two
randomized, double-blind, active-controlled, multinational, multicenter studies
(Studies 308 and 313). These studies compared tigecycline (100 mg intravenous
initial dose followed by 50 mg every 12 hours) with levofloxacin (500 mg
intravenous every 12 or 24 hours). In one study (Study 308), after at least 3
days of intravenous therapy, a switch to oral levofloxacin (500 mg daily) was
permitted for both treatment arms. Total therapy was 7 to 14 days. Patients
with community-acquired bacterial pneumonia who required hospitalization and
intravenous therapy were enrolled in the studies. The primary efficacy endpoint
was the clinical response at the test of cure  (TOC) visit in the
co-primary populations of the clinically evaluable (CE) and clinical modified
intent-to-treat (c-mITT) patients. See Table 10. Clinical cure rates at TOC by
pathogen in the microbiologically evaluable patients are presented in Table 11.
Table 10: Clinical Cure
Rates from Two Studies in Community-Acquired Bacterial Pneumonia after 7 to 14
Days of Total Therapy
|
Tigecyclinea
n/N (%) |
Levofloxacinb
n/N (%) |
95% CIc |
Study 308d |
CE |
125/138 (90.6) |
136/156 (87.2) |
(-4.4, 11.2) |
c-mITT |
149/191 (78) |
158/203 (77.8) |
(-8.5, 8.9) |
Study 313 |
CE |
128/144 (88.9) |
116/136 (85.3) |
(-5, 12.2) |
c-mITT |
170/203 (83.7) |
163/200 (81.5) |
(-5.6, 10.1) |
a 100 mg initially, followed by 50 mg every 12
hours
b Levofloxacin (500 mg intravenous every 12 or 24 hours)
c 95% confidence interval for the treatment difference
d After at least 3 days of intravenous therapy, a switch to oral
levofloxacin (500 mg daily) was permitted for both treatment arms in Study 308. |
Table 11: Clinical Cure Rates by Infecting Pathogen in
Microbiologically Evaluable Patients with Community-Acquired Bacterial
Pneumoniaa
Pathogen |
Tigecycline
n/N (%) |
Levofloxacin
n/N (%) |
Haemophilus influenzae |
14/17 (82.4) |
13/16 (81.3) |
Legionella pneumophila |
10/10 (100.0) |
6/6 (100.0) |
Streptococcus pneumoniae (penicillin-susceptible only)b |
44/46 (95.7) |
39/44 (88.6) |
a Two CABP studies
b Includes cases of concurrent bacteremia [cure rates of 20/22
(90.9%) versus 13/18 (72.2%) for tigecycline and levofloxacin respectively] |
To further evaluate the
treatment effect of tigecycline, a post-hoc analysis was conducted in CABP
patients with a higher risk of mortality, for whom the treatment effect of
antibiotics is supported by historical evidence. The higher-risk group included
CABP patients from the two studies with any of the following factors:
- Age ≥ 50 years
- PSI score ≥ 3
- Streptococcus pneumoniae bacteremia
The results of this analysis are shown in Table 12. Age
≥ 50 was the most common risk factor in the higher-risk group.
Table 12: Post-hoc Analysis of Clinical Cure Rates in
Patients with Community-Acquired Bacterial Pneumonia Based on Risk of Mortalitya
|
Tigecycline
n/N (%) |
Levofloxacin
n/N (%) |
95% CIb |
Study 308c |
CE |
Higher risk |
Yes |
93/103 (90.3) |
84/102 (82.4) |
(-2.3, 18.2) |
No |
32/35 (91.4) |
52/54 (96.3) |
(-20.8, 7.1) |
c-mITT |
Higher risk |
Yes |
111/142 (78.2) |
100/134 (74.6) |
(-6.9, 14) |
No |
38/49 (77.6) |
58/69 (84.1) |
(-22.8, 8.7) |
Study 313 |
CE |
Higher risk |
Yes |
95/107 (88.8) |
68/85 (80) |
(-2.2, 20.3) |
No |
33/37 (89.2) |
48/51 (94.1) |
(-21.1, 8.6) |
c-mITT |
Higher risk |
Yes |
112/134 (83.6) |
93/120 (77.5) |
(-4.2, 16.4) |
No |
58/69 (84.1) |
70/80 (87.5) |
(-16.2, 8.8) |
a Patients at higher risk of death include
patients with any one of the following: ≥ 50 years of age; PSI score
≥ 3; or bacteremia due to Streptococcus pneumoniae
b 95% confidence interval for the treatment difference
c After at least 3 days of intravenous therapy, a switch to oral
levofloxacin (500 mg daily) was permitted for both treatment arms in Study 308. |
REFERENCES
1. Clinical and Laboratory Standards Institute (CLSI). Methods
for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow
Aerobically; Approved Standard -Tenth Edition. CLSI document M07-A10, Clinical
and Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne,
Pennsylvania 19087, USA, 2015.
2. Clinical and Laboratory Standards Institute (CLSI). Performance
Standards for Antimicrobial Disk Diffusion Susceptibility Tests; Approved
Standard - Twelfth Edition. CLSI document M02-A12, Clinical and Laboratory
Standards Institute, 950 West Valley Road, Suite 2500, Wayne, Pennsylvania
19087, USA, 2015.
3. Clinical and Laboratory Standards Institute (CLSI). Methods
for Antimicrobial Susceptibility Testing of Anaerobic Bacteria; Approved
Standard - Eighth Edition. CLSI document M11-A8. Clinical and Laboratory
Standards Institute, 950 West Valley Road, Suite 2500, Wayne, PA 19087, USA,
2012.
4. Clinical and Laboratory Standards Institute (CLSI). Performance
Standards for Antimicrobial Susceptibility Testing; Twenty-fifth Informational
Supplement, CLSI document M100-S25. CLSI document M100-S23, Clinical and
Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne,
Pennsylvania 19087, USA, 2015.