Mechanism of Action
Tigecycline is an antibacterial drug.
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 2. Intravenous infusions of tigecycline were
administered over approximately 30 to 60 minutes.
Table 2. 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) |
- |
4.70 (36%) |
| Cmin (mcg/mL) |
- |
0.13 (59%) |
| t˝ (h) |
27.1 (53%) |
42.4 (83%) |
| CL (L/h) |
21.8 (40%) |
23.8 (33%) |
| CLτ (mL/min) (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.
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.
Elimination
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
Patients with 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].
Patients with 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 TYGACIL 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 65-75; n=13, age > 75) and younger subjects (n=18)
receiving a single 100-mg dose of TYGACIL. Therefore, no dosage adjustment is
necessary based on age [see Use in Specific Populations].
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 (23.0±7.8 L/h), Hispanic subjects
(24.3±6.5 L/h), White subjects (22.1±8.9 L/h), and “other” subjects (25.0±4.8
L/h). Therefore, no dosage adjustment is necessary based on race.
Drug Interactions
TYGACIL (100 mg followed by 50 mg every 12 hours) and digoxin (0.5 mg followed
by 0.25 mg, orally, every 24 hours) were coadministered 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 TYGACIL is administered with digoxin.
Concomitant administration of TYGACIL (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,
TYGACIL 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, a glycylcycline, 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. Tigecycline
carries a glycylamido moiety attached to the 9-position of minocycline. The
substitution pattern is not present in any naturally occurring or semisynthetic
tetracycline and imparts certain microbiologic properties to tigecycline. In
general, tigecycline is considered bacteriostatic; however, TYGACIL has
demonstrated bactericidal activity against isolates of S. pneumoniae and L.
pneumophila.
Mechanism(s) of Resistance
To date there has been no cross-resistance observed between
tigecycline and other antibacterials. Tigecycline is not 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 beta-lactamases), target-site
modifications, macrolide efflux pumps or enzyme target changes (e.g.
gyrase/topoisomerases). 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.
Tigecycline has been shown to be active against most of the following bacteria,
both in vitro and in clinical infections [see INDICATIONS
AND USAGE].
Facultative Gram-positive bacteria
Enterococcus faecalis (vancomycin-susceptible isolates)
Staphylococcus aureus (methicillin-susceptible and -resistant isolates)
Streptococcus agalactiae
Streptococcus anginosus grp. (includes S. anginosus,
S. intermedius, and S. constellatus)
Streptococcus pneumoniae (penicillin-susceptible isolates)
Streptococcus pyogenes
Facultative Gram-negative bacteria
Citrobacter freundii
Enterobacter cloacae
Escherichia coli
Haemophilus influenzae (beta-lactamase negative isolates)
Klebsiella oxytoca
Klebsiella pneumoniae
Legionella
pneumophila
Anaerobic bacteria
Bacteroides fragilis
Bacteroides thetaiotaomicron
Bacteroides uniformis
Bacteroides vulgatus
Clostridium perfringens
Peptostreptococcus micros
At least 90% of the following bacteria exhibit in vitro
minimum inhibitory concentrations (MICs) that are at concentrations that are
achievable using the prescribed dosing regimens. However, the clinical significance
of this is unknown because the safety and effectiveness of tigecycline in
treating clinical infections due to these bacteria have not been established in
adequate and well-controlled clinical trials.
Facultative 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
Facultative 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 the most effective antimicrobial.
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 based on dilution methods (broth,
agar, or microdilution)1,3,4 or equivalent using standardized inoculum and
concentrations of tigecycline. 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 3.
Diffusion Techniques
Quantitative methods that require measurement of zone
diameters also provide reproducible estimates of the susceptibility of bacteria
to antimicrobial compounds. The standardized procedure2,4 requires the use of
standardized inoculum concentrations. This procedure uses paper disks
impregnated with 15 mcg tigecycline to test the susceptibility of bacteria to
tigecycline. Interpretation involves correlation of the diameter obtained in
the disk test with the MIC for tigecycline. Reports from the laboratory
providing results of the standard single-disk susceptibility test with a 15 mcg
tigecycline disk should be interpreted according to the criteria in Table 3.
Anaerobic Techniques
Anaerobic susceptibility testing with tigecycline should be
done by the agar dilution method3 since quality control parameters for
broth-dilution are not established.
Table 3. 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 (vancomycinsusceptible isolates) |
≤ 0.25a |
- |
- |
≥ 19 |
- |
- |
| Enterobacteriaceaeb |
≤ 2 |
4 |
≥ 8 |
≥ 19 |
15-18 |
≤ 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” indicates that the pathogen is
likely to be inhibited if the antimicrobial compound reaches the concentrations
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 that 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 reaches the concentrations usually achievable; other
therapy should be selected.
Quality Control
As with other susceptibility techniques, the use of
laboratory control microorganisms is required to control the technical aspects
of the laboratory standardized procedures.1,2,3,4 Standard tigecycline powder
should provide the MIC values provided in Table 4. For the diffusion technique
using the 15 mcg tigecycline disk the criteria provided in Table 4 should be
achieved.
Table 4. Acceptable Quality Control Ranges for
Susceptibility Testing
| QC organism |
Minimum Inhibitory
Concentrations (mcg/mL) |
Disk Diffusion
(zone diameters in mm) |
| Staphylococcus aureus ATCC 25923 |
Not Applicable |
20-25 |
| Staphylococcus aureus ATCC 29213 |
0.03-0.25 |
Not Applicable |
| Escherichia coli ATCC 25922 |
0.03-0.25 |
20-27 |
| Enterococcus faecalis ATCC 29212 |
0.03-0.12 |
Not Applicable |
| Streptococcus pneumoniae ATCC 49619 |
0.016-0.12 |
23-29 |
| Haemophilus influenzae ATCC 49247 |
0.06-0.5 |
23-31 |
| Bacteroides fragilisa ATCC 25285 |
0.12-1 |
Not Applicable |
| Bacteroides thetaiotaomicrona ATCC 29741 |
0.5-2 |
Not Applicable |
| Eubacterium lentuma ATCC 43055 |
0.06-0.5 |
Not Applicable |
| Clostridium difficilea ATCC 70057 |
0.12-1 |
Not Applicable |
ATCC = American Type Culture Collection
a Agar dilution |
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
TYGACIL 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 TYGACIL (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 5. Clinical cure rates at TOC by pathogen in the microbiologically
evaluable patients are presented in Table 6.
Table 5. Clinical Cure Rates from Two Studies in Complicated
Skin and Skin Structure Infections after 5 to 14 Days of Therapy
| |
TYGACILa
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
bVancomycin (1 g every 12 hours)/Aztreonam (2 g every 12 hours) |
Table 6. Clinical Cure Rates By Infecting Pathogen in
Microbiologically Evaluable Patients with Complicated Skin and Skin Structure
Infectionsa
| Pathogen |
TYGACIL
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 grp.b |
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
TYGACIL 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 TYGACIL (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 7. Clinical
cure rates at TOC by pathogen in the microbiologically evaluable patients are
presented in Table 8.
Table 7. Clinical Cure Rates from Two Studies in Complicated
Intra-abdominal Infections after 5 to 14 Days of Therapy
| |
TYGACILa
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
bImipenem/Cilastatin (500 mg every 6 hours) |
Table 8. Clinical Cure Rates By Infecting Pathogen in
Microbiologically Evaluable Patients with Complicated Intra-abdominal
Infectionsa
| Pathogen |
TYGACIL
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 grp.b |
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
TYGACIL 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 TYGACIL (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 9. Clinical cure rates at TOC by pathogen in the
microbiologically evaluable patients are presented in Table 10.
Table 9. Clinical Cure Rates from Two Studies in
Community-Acquired Bacterial Pneumonia after 7 to 14 Days of Total Therapy
| |
TYGACILa
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) |
(-5.0, 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
bLevofloxacin (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 10. Clinical Cure Rates By Infecting Pathogen in
Microbiologically Evaluable Patients with Community-Acquired Bacterial
Pneumoniaa
| Pathogen |
TYGACIL
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 TYGACIL 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 11. Age
≥ 50 was the most common risk factor in the higher-risk group.
Table 11. Post-hoc Analysis of Clinical Cure Rates in
Patients with Community-Acquired Bacterial Pneumonia Based on Risk of
Mortalitya
| |
TYGACIL
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 year 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 – 8th ed. Approved Standard, CLSI document M07-A8, CLSI, 940 West Valley Road, Suite 1400, Wayne, PA 19087-1898. January 2009.
2. Clinical and Laboratory Standards Institute (CLSI).
Performance Standards for Antimicrobial Disk Diffusion Susceptibility Tests –
10th ed. Approved Standard, CLSI document M02-A10, CLSI, 940 West Valley Road,
Suite 1400, Wayne, PA 19087-1898. January 2009.
3. Clinical and Laboratory Standards Institute (CLSI). Methods
for Antimicrobial Susceptibility Testing of Anaerobic Bacteria – 7th ed.
Approved Standard, CLSI document M11-A7, CLSI, 940 West Valley Road, Suite 1400,
Wayne, PA 19087-1898. January 2007.
4. Clinical and Laboratory Standards Institute (CLSI).
Performance Standards for Antimicrobial Susceptibility Testing – 19th
Informational Supplement. Approved Standard, CLSI document M100-S19, CLSI, 940 West Valley Road, Suite 1400, Wayne, PA 19087-1898. January 2009.
Last updated on RxList: 4/16/2009