CLINICAL PHARMACOLOGY
After an intravenous infusion (30 min.) of 3.1 grams of TIMENTIN, peak serum
concentrations of both ticarcillin and clavulanic acid are attained immediately
after completion of infusion. Ticarcillin serum levels are similar to those
produced by the administration of equivalent amounts of ticarcillin alone with
a mean peak serum level of 330 mcg/mL. The corresponding mean peak serum level
for clavulanic acid is 8 mcg/mL. (See following table.)
SERUM LEVELS IN ADULTS AFTER A 30-MINUTE IV INFUSION OF TIMENTIN®
TICARCILLIN SERUM LEVELS (mcg/mL)
Dose |
0 |
15 min. |
30 min. |
1 hr. |
1.5 hr. |
3.5 hr. |
5.5 hr. |
3.1 gram |
324 (293 to 388) |
223 (184 to 293) |
176 (135 to 235) |
131 (102 to 195) |
90 (65 to 119) |
27 (19 to 37) |
6 (5 to 7) |
|
CLAVULANIC ACID SERUM LEVELS (mcg/mL) |
Dose |
0 |
15 min. |
30 min. |
1 hr. |
1.5 hr. |
3.5 hr. |
5.5 hr. |
3.1 gram |
8.0 (5.3 to 10.3) |
4.6 (3.0 to 7.6) |
2.6 (1.8 to 3.4) |
1.8 (1.6 to 2.2) |
1.2 (0.8 to 1.6) |
0.3 (0.2 to 0.3) |
0 |
The mean area under the serum concentration curve was 485 mcg•hr/mL for
ticarcillin and 8.2 mcg•hr/mL for clavulanic acid.
The mean serum half-lives of ticarcillin and clavulanic acid in healthy volunteers
are 1.1 hours and 1.1 hours, respectively.
In pediatric patients receiving approximately 50 mg/kg of TIMENTIN (30:1 ratio
ticarcillin to clavulanate), mean ticarcillin serum half-lives were 4.4 hours
in neonates (n = 18) and 1.0 hour in infants and children (n = 41). The corresponding
clavulanate serum half-lives averaged 1.9 hours in neonates (n = 14) and 0.9
hour in infants and children (n = 40). Area under the serum concentration time
curves averaged 339 mcg•hr/mL in infants and children (n = 41), whereas
the corresponding mean clavulanate area under the serum concentration time curves
was approximately 7 mcg•hr/mL in the same population (n = 40).
Approximately 60% to 70% of ticarcillin and approximately 35% to 45% of clavulanic
acid are excreted unchanged in urine during the first 6 hours after administration
of a single dose of TIMENTIN to normal volunteers with normal renal function.
Two hours after an intravenous injection of 3.1 grams of TIMENTIN, concentrations
of ticarcillin in urine generally exceed 1,500 mcg/mL. The corresponding concentrations
of clavulanic acid in urine generally exceed 40 mcg/mL. By 4 to 6 hours after
injection, the urine concentrations of ticarcillin and clavulanic acid usually
decline to approximately 190 mcg/mL and 2 mcg/mL, respectively. Neither component
of TIMENTIN is highly protein bound; ticarcillin has been found to be approximately
45% bound to human serum protein and clavulanic acid approximately 25% bound.
Somewhat higher and more prolonged serum levels of ticarcillin can be achieved
with the concurrent administration of probenecid; however, probenecid does not
enhance the serum levels of clavulanic acid.
Ticarcillin can be detected in tissues and interstitial fluid following parenteral
administration.
Penetration of ticarcillin into bile and pleural fluid has been demonstrated.
The results of experiments involving the administration of clavulanic acid to
animals suggest that this compound, like ticarcillin, is well distributed in
body tissues.
An inverse relationship exists between the serum half-life of ticarcillin and creatinine clearance. The dosage of TIMENTIN need only be adjusted in cases
of severe renal impairment. (See DOSAGE AND ADMINISTRATION.)
Ticarcillin may be removed from patients undergoing dialysis; the actual amount
removed depends on the duration and type of dialysis.
Microbiology
Ticarcillin is a semisynthetic antibiotic with a broad spectrum of bactericidal
activity against many gram-positive and gram-negative aerobic and anaerobic
bacteria.
Ticarcillin is, however, susceptible to degradation by β-lactamases, and
therefore, the spectrum of activity does not normally include organisms which
produce these enzymes.
Clavulanic acid is a β-lactam, structurally related to the penicillins,
which possesses the ability to inactivate a wide range of β-lactamase enzymes
commonly found in microorganisms resistant to penicillins and cephalosporins.
In particular, it has good activity against the clinically important plasmid-mediated
β-lactamases frequently responsible for transferred drug resistance.
The formulation of ticarcillin with clavulanic acid in TIMENTIN protects ticarcillin
from degradation by β-lactamase enzymes and effectively extends the antibiotic
spectrum of ticarcillin to include many bacteria normally resistant to ticarcillin
and other β-lactam antibiotics. Thus, TIMENTIN possesses the distinctive
properties of a broad-spectrum antibiotic and a β-lactamase inhibitor.
Ticarcillin/clavulanic acid 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.
Gram-Positive Aerobes
Staphylococcus aureus (β-lactamase and non–β-lactamase–producing)*
Staphylococcus epidermidis (β-lactamase and non–β-lactamase–producing)*
*Staphylococci that are resistant to methicillin/oxacillin must be considered
resistant to ticarcillin/clavulanic acid.
Gram-Negative Aerobes
Citrobacter species (β-lactamase and non–β-lactamase–producing)
Enterobacter species including E. cloacae (β-lactamase and
non–β-lactamase–producing)
(Although most strains of Enterobacter species are resistant in vitro ,
clinical efficacy has been demonstrated with TIMENTIN in urinary tract infections
and gynecologic infections caused by these organisms.)
Escherichia coli (β-lactamase and non–β-lactamase–producing)
Haemophilus influenzae (β-lactamase and non–β-lactamase–producing)†
Klebsiella species including K. pneumoniae (β-lactamase
and non–β-lactamase–producing)
Pseudomonas species including P. aeruginosa (β-lactamase
and non–β-lactamase–producing)
Serratia marcescens (β-lactamase and non–β-lactamase–producing)
†β-lactamase–negative, ampicillin-resistant (BLNAR) strains of
H. influenzae must be considered resistant to ticarcillin/clavulanic acid.
Anaerobic Bacteria
Bacteroides fragilis group (β-lactamase and non–β-lactamase–producing)
Prevotella (formerly Bacteroides) melaninogenicus (β-lactamase
and non–β-lactamase– producing)
The following in vitro data are available, but their clinical significance
is unknown.
The following strains exhibit an in vitro minimum inhibitory concentration
(MIC) less than or equal to the susceptible breakpoint for ticarcillin/clavulanic
acid. However, with the exception of organisms shown to respond to ticarcillin
alone, the safety and effectiveness of ticarcillin/clavulanic acid in treating
infections due to these microorganisms have not been established in adequate
and well-controlled clinical trials.
Gram-Positive Aerobes
Staphylococcus saprophyticus (β-lactamase and non–β-lactamase–producing)
Streptococcus agalactiae‡ (Group B)
Streptococcus bovis‡
Streptococcus pneumoniae‡(penicillin-susceptible strains only)
Streptococcus pyogenes‡
Viridans group streptococci‡
Gram-Negative Aerobes
Acinetobacter baumannii (β-lactamase and non–β-lactamase–producing)
Acinetobacter calcoaceticus (β-lactamase and non–β-lactamase–producing)
Acinetobacter haemolyticus (β-lactamase and non–β-lactamase–producing)
Acinetobacter lwoffi (β-lactamase and non–β-lactamase–producing)
Moraxella catarrhalis (β-lactamase and non–β-lactamase–producing)
Morganella morganii (β-lactamase and non–β-lactamase–producing)
Neisseria gonorrhoeae (β-lactamase and non–β-lactamase–producing)
Pasteurella multocida (β-lactamase and non–β-lactamase–producing)
Proteus mirabilis (β-lactamase and non–β-lactamase–producing)
Proteus penneri (β-lactamase and non–β-lactamase–producing)
Proteus vulgaris (β-lactamase and non–β-lactamase–producing)
Providencia rettgeri (β-lactamase and non–β-lactamase–producing)
Providencia stuartii (β-lactamase and non–β-lactamase–producing)
Stenotrophomonas maltophilia (β-lactamase and non–β-lactamase–producing)
Anaerobic Bacteria
Clostridium species including C. perfringens, C. difficile,
C. sporogenes, C. ramosum, and C. bifermentans (β-lactamase
and non–β-lactamase–producing)
Eubacterium species
Fusobacterium species including F. nucleatum and F. necrophorum
(β-lactamase and non–βlactamase–producing)
Peptostreptococcus species‡
Veillonella species‡
‡These are non–β-lactamase–producing strains, and therefore, are
susceptible to ticarcillin.
In vitro synergism between TIMENTIN and gentamicin, tobramycin, or amikacin
against multiresistant strains of Pseudomonas aeruginosa has been demonstrated.
Susceptibility Testing
Dilution Techniques: Quantitative methods are used to determine antimicrobial
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 method1,3 (broth or agar) or equivalent
with standardized inoculum concentrations and standardized concentrations of
ticarcillin/clavulanate potassium powder.
The recommended dilution pattern utilizes a constant level of 2 mcg/mL clavulanic
acid in all tubes with varying amounts of ticarcillin. MICs are expressed in
terms of the ticarcillin concentration in the presence of clavulanic acid at
a constant 2 mcg/mL. The MIC values should be interpreted according to the following
criteria:
RECOMMENDED RANGES FOR TICARCILLIN/CLAVULANIC ACID SUSCEPTIBILITY TESTING*
For Pseudomonas aeruginosa:
MIC (mcg/mL) |
Interpretation |
≤ 64 |
Susceptible (S) |
≥ 128 |
Resistant (R) |
For Enterobacteriaceae:
MIC (mcg/mL) |
Interpretation |
≤ 16 |
Susceptible(S) |
32-64 |
Intermediate(I) |
≥ 128 |
Resistant(R) |
For Staphylococci†:
MIC (mcg/mL) |
Interpretation |
≤ 8 |
Susceptible(S) |
≥ 16 |
Resistant(R) |
*Expressed as concentration of ticarcillin in the presence of clavulanic acid
at a constant 2 mcg/mL.
† Staphylococci that are susceptible to ticarcillin/clavulanic acid but
resistant to methicillin/oxacillin must be considered as resistant.
A report of “Susceptible” indicates that the pathogen is likely
to be inhibited if the antimicrobial compound in the blood 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 in the blood reaches the concentrations 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 ticarcillin/clavulanate potassium powder should provide the following
MIC values3:
Microorganism |
|
MIC (mcg/mL)‡ |
Escherichia coli |
ATCC 25922 |
4-16 |
Escherichia coli |
ATCC 35218 |
8-32 |
Pseudomonas aeruginosa |
ATCC 27853 |
8-32 |
Staphylococcus aureus |
ATCC 29213 |
0.5-2 |
‡Expressed as concentration of ticarcillin
in the presence of clavulanic acid at a constant 2 mcg/mL. |
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 procedure2,3
requires the use of standardized inoculum concentrations. This procedure uses
paper disks impregnated with 85 mcg of ticarcillin/clavulanate potassium (75
mcg ticarcillin plus 10 mcg clavulanate potassium) to test the susceptibility
of microorganisms to ticarcillin/clavulanic acid.
Reports from the laboratory providing results of the standard single-disk susceptibility
test with an 85 mcg of ticarcillin/clavulanate potassium (75 mcg ticarcillin
plus 10 mcg clavulanate potassium) disk should be interpreted according to the
following criteria:
RECOMMENDED RANGES FOR TICARCILLIN/CLAVULANIC ACID SUSCEPTIBILITY TESTING
For Pseudomonas aeruginosa:
Zone Diameter (mm) |
Interpretation |
≥ 15 |
Susceptible(S) |
≤ 14 |
Resistant(R) |
For Enterobacteriaceae:
Zone Diameter (mm) |
Interpretation |
≥ 20 |
Susceptible(S) |
15-19 |
Intermediate(I) |
≤ 14 |
Resistant(R) |
For Staphylococci§:
Zone Diameter (mm) |
Interpretation |
≥ 23 |
Susceptible(S) |
≤ 22 |
Resistant(R) |
§ Staphylococci that are resistant to
methicillin/oxacillin must be considered as resistant to ticarcillin/clavulanic
acid. |
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 ticarcillin/clavulanic acid.
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 85 mcg
of ticarcillin/clavulanate potassium (75 mcg ticarcillin plus 10 mcg clavulanate
potassium) disk should provide the following zone diameters in these laboratory
test quality control strains:
Microorganism |
|
Zone Diameter (mm) |
Escherichia coli |
ATCC 25922 |
24-30 |
Escherichia coli |
ATCC 35218 |
21-25 |
Pseudomonas aeruginosa |
ATCC 27853 |
20-28 |
Staphylococcus aureus |
ATCC 25923 |
29-37 |
Anaerobic Techniques: For anaerobic bacteria, the susceptibility to
ticarcillin/clavulanic acid can be determined by standardized test methods3,4.
The MIC values obtained should be interpreted according to the following criteria:
RECOMMENDED RANGES FOR TICARCILLIN/CLAVULANIC ACID SUSCEPTIBILITY
TESTING||
MIC (mcg/mL) |
Interpretation |
≤ 32 |
Susceptible(S) |
64 |
Intermediate(I) |
≥ 128 |
Resistant(R) |
|| Expressed as concentration of ticarcillin
in the presence of clavulanic acid at a constant 2 mcg/mL. |
Interpretation is identical to that stated above for results using dilution
techniques.
As with other susceptibility techniques, the use of laboratory control microorganisms
is required to control the technical aspects of the laboratory standardized
procedures. Standardized ticarcillin/clavulanate potassium powder should provide
the following MIC values:
Microorganism |
|
Agar dilution MIC Range (mcg/mL)|| |
Broth microdilution MIC Range (mcg/mL)|| |
Bacteroides thetaiotaomicron |
ATCC 29741 |
0.5-2 |
0.5-2 |
Eubacterium lentum |
ATCC 43055 |
16-64 |
8-32 |
||Expressed as concentration of ticarcillin
in the presence of clavulanic acid at a constant 2 mcg/mL. |
Clinical Studies
TIMENTIN has been studied in a total of 296 pediatric patients (excluding neonates
and infants less than 3 months) in 6 controlled clinical trials. The majority
of patients studied had intra-abdominal infections, and the primary comparator
was clindamycin and gentamicin with or without ampicillin. At the end-of-therapy
visit, comparable efficacy was reported in the trial arms using TIMENTIN and
an appropriate comparator.
TIMENTIN was also evaluated in an additional 408 pediatric patients (excluding
neonates and infants less than 3 months) in 3 uncontrolled US clinical trials.
Patients were treated across a broad range of presenting diagnoses including:
Infections in bone and joint, skin and skin structure, lower respiratory tract,
urinary tract, as well as intra-abdominal and gynecologic infections. Patients
received TIMENTIN either 300 mg/kg/day (based on the ticarcillin component)
divided every 4 hours for severe infection or 200 mg/kg/day (based on the ticarcillin
component) divided every 6 hours for mild to moderate infections. The efficacy
rates were comparable to those obtained in the controlled trials.
The adverse event profile in these 704 pediatric patients treated with TIMENTIN
was comparable to that seen in adult patients.
REFERENCES
1. Clinical and Laboratory Standards Institute (CLSI). Methods
for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically
– Seventh Edition. Approved Standard CLSI Document M7-A7, Vol. 26, No. 2. CLSI,
Wayne, PA, Jan. 2006.
2. Clinical and Laboratory Standards Institute (CLSI). Performance
Standard for Antimicrobial Disk Susceptibility Tests – Ninth Edition. Approved
Standard CLSI Document M2-A9, Vol. 26, No. 1. CLSI, Wayne, PA, Jan. 2006.
3. Clinical and Laboratory Standards Institute (CLSI). Performance
Standards for Antimicrobial Susceptibility Testing: Eighteenth Informational
Supplement. Approved Standard CLSI Document M100-S18, Vol. 28, No. 1. CLSI,
Wayne, PA, Jan. 2008.
4. Clinical and Laboratory Standards Institute (CLSI). Methods
for Antimicrobial Susceptibility Testing of Anaerobic Bacteria – Seventh Edition. Approved Standard CSLI Document M11A7, Vol. 27, No. 2. CLSI, Wayne, PA, 2007.