CLINICAL PHARMACOLOGY
The pharmacokinetics of amoxicillin and clavulanate were determined in a study
of 19 pediatric patients, 8 months to 11 years, given AUGMENTIN ES-600 at an
amoxicillin dose of 45 mg/kg every 12 hours with a snack or meal. The mean plasma
amoxicillin and clavulanate pharmacokinetic parameter values are listed in the
following table.
Table 1: Mean (±SD) Plasma Amoxicillin and Clavulanate
Pharmacokinetic Parameter Values Following Administration of 45 mg/kg of AUGMENTIN
ES-600 Every 12 Hours to Pediatric Patients
Parametera |
Amoxicillin |
Clavulanate |
Cmax (mcg/mL) |
15.7 ±7.7 |
1.7 ±0.9 |
Tmax (hr) |
2.0 (1.0 – 4.0) |
1.1 (1.0 – 4.0) |
AUC0-t (mcg•hr/mL) |
59.8 ±20.0 |
4.0 ±1.9 |
T½ (hr) |
1.4 ±0.3 |
1.1 ±0.3 |
CL/F (L/hr/kg) |
0.9 ±0.4 |
1.1 ±1.1 |
a Arithmetic mean ± standard
deviation, except Tmax values which are medians (ranges). |
The effect of food on the oral absorption of AUGMENTIN ES-600 has not been
studied.
Approximately 50% to 70% of the amoxicillin and approximately 25% to 40% of
the clavulanic acid are excreted unchanged in urine during the first 6 hours
after administration of 10 mL of 250 mg/5 mL suspension of AUGMENTIN.
Concurrent administration of probenecid delays amoxicillin excretion but does
not delay renal excretion of clavulanic acid.
Neither component in AUGMENTIN ES-600 is highly protein-bound; clavulanic acid
has been found to be approximately 25% bound to human serum and amoxicillin
approximately 18% bound.
Oral administration of a single dose of AUGMENTIN ES-600 at 45 mg/kg (based
on the amoxicillin component) to pediatric patients, 9 months to 8 years, yielded
the following pharmacokinetic data for amoxicillin in plasma and middle ear
fluid (MEF).
Table 2: Amoxicillin Concentrations in Plasma and Middle
Ear Fluid Following Administration of 45 mg/kg of AUGMENTIN ES-600 to Pediatric
Patients
Timepoint |
Amoxicillin concentration in plasma (mcg/mL) |
Amoxicillin concentration in MEF (mcg/mL) |
1 hour |
mean |
7.7 |
3.2 |
median |
9.3 |
3.5 |
range |
1.5 – 14.0 |
0.2 – 5.5 |
(n = 5) |
(n = 4) |
2 hour |
mean |
15.7 |
3.3 |
median |
13.0 |
2.4 |
range |
11.0 – 25.0 |
1.9 – 6 |
(n = 7) |
(n = 5) |
3 hour |
mean |
13.0 |
5.8 |
median |
12.0 |
6.5 |
range |
5.5 – 21.0 |
3.9 – 7.4 |
(n = 5) |
(n = 5) |
Dose administered immediately prior to eating.
Amoxicillin diffuses readily into most body tissues and fluids with the exception
of the brain and spinal fluid. The results of experiments involving the administration
of clavulanic acid to animals suggest that this compound, like amoxicillin,
is well distributed in body tissues.
Microbiology
Amoxicillin is a semisynthetic antibiotic with a broad spectrum of bactericidal
activity against many gram-positive and gram-negative microorganisms. Amoxicillin
is, however, susceptible to degradation by β-lactamases, and therefore,
its spectrum of activity does not include organisms which produce these enzymes.
Clavulanic acid is a β-lactam, structurally related to penicillin, 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 found responsible for transferred drug resistance.
The clavulanic acid component of AUGMENTIN ES-600 protects amoxicillin from
degradation by β-lactamase enzymes and effectively extends the antibiotic
spectrum of amoxicillin to include many bacteria normally resistant to amoxicillin
and other β-lactam antibiotics. Thus, AUGMENTIN ES-600 possesses the distinctive
properties of a broad-spectrum antibiotic and a β-lactamase inhibitor.
Amoxicillin/clavulanic acid has been shown to be active against most isolates
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 isolates with penicillin MICs ≤
2 mcg/mL)
Aerobic Gram-Negative Microorganisms
Haemophilus influenzae (including β-lactamase–producing isolates)
Moraxella catarrhalis (including β-lactamase–producing isolates)
The following in vitro data are available, but their clinical significance
is unknown.
At least 90% of the following microorganisms exhibit in vitro minimum
inhibitory concentrations (MICs) less than or equal to the susceptible breakpoint
for amoxicillin/clavulanic acid. However, the safety and efficacy of amoxicillin/clavulanic
acid in treating infections due to these microorganisms have not been established
in adequate and well-controlled trials.
Aerobic Gram-Positive Microorganisms
Staphylococcus aureus (including β-lactamase–producing isolates)
NOTE: Staphylococci which are resistant to methicillin/oxacillin must
be considered resistant to amoxicillin/clavulanic acid. Streptococcus pyogenes
NOTE: S. pyogenes do not produce β-lactamase, and therefore, are
susceptible to amoxicillin alone. Adequate and well-controlled clinical trials
have established the effectiveness of amoxicillin alone in treating certain
clinical infections due to S. pyogenes.
Susceptibility Test Methods
When available, the clinical microbiology laboratory should provide cumulative
results of 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 Technique: 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.1,2 Standardized procedures are based
on dilution methods (broth for S. pneumoniae and H. influenzae)
or equivalent with standardized inoculum concentration and standardized concentrations
of amoxicillin/clavulanate potassium powder.
The recommended dilution pattern utilizes a constant amoxicillin/clavulanate
potassium ratio of 2 to 1 in all tubes with varying amounts of amoxicillin.
MICs are expressed in terms of the amoxicillin concentration in the presence
of clavulanic acid at a constant 2 parts amoxicillin to 1 part clavulanic acid.
The MIC values should be interpreted according to criteria provided in Table
3.
Diffusion Technique: Quantitative methods that require measurement of
zone diameters also provides reproducible estimates of the susceptibility of
bacteria to antimicrobials. One such standardized technique requires the use
of a standardized inoculum concentration.2,3 This procedure uses
paper disks impregnated with 30 mcg amoxicillin/clavulanate potassium (20 mcg
amoxicillin plus 10 mcg clavulanate potassium) to test susceptibility of microorganisms
to amoxicillin/clavulanate potassium. Disk diffusion zone sizes should be interpreted
according to criteria provided in Table 3.
Table 3: Susceptibility Test Result Interpretive Criteria
for Amoxicillin/Clavulanate Potassium
Pathogen |
Minimum Inhibitory Concentration (mcg/mL) |
Disk Diffusion (Zone Diameter in mm) |
S |
I |
R |
S |
I |
R |
Streptococcus pneumoniae (nonÂmeningitis isolates) |
≤ 2/1 |
4/2 |
≥ 8/4 |
|
Not applicable (NA) |
|
Haemophilus influenzae |
≤ 4/2 |
NA |
≥ 8/4 |
≥ 20 |
NA |
≤ 19 |
NOTE: Susceptibility of S. pneumoniae should be determined using a 1-mcg
oxacillin disk. Isolates with oxacillin zone sizes of ≥ 20 mm are susceptible
to amoxicillin/clavulanic acid. An amoxicillin/clavulanic acid MIC should be
determined on isolates of S. pneumoniae with oxacillin zone sizes of ≤ 19
mm.
NOTE: β-lactamase–negative, ampicillin-resistant H. influenzae
isolates must be considered resistant to amoxicillin/clavulanic acid.
A report of S (“Susceptible”) indicates that the antimicrobial
is likely to inhibit growth of the pathogen if the antimicrobial compound in
the blood reaches the concentration usually achievable. A report of I (“Intermediate”)
indicates that the result should be considered equivocal, and, if the microorganism
is not fully susceptible to alternative, clinically feasible antimicrobials,
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 doses of antimicrobial 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 R (“Resistant”)
indicates that the antimicrobial is not likely to inhibit growth of the pathogen
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 quality control
microorganisms to determine the performance of the test procedures.1-3
Standard amoxicillin/clavulanate potassium powder should provide the MIC ranges
for the quality control organisms in Table 4. For the disk diffusion technique,
the 30 mcg-amoxicillin/clavulanate potassium disk should provide the zone diameter
ranges for the quality control organisms in Table 4.
Table 4: Acceptable Quality Control Ranges for Amoxicillin/Clavulanate
Potassium
Quality Control Organism |
Minimum Inhibitory Concentration Range (mcg/mL) |
Disk Diffusion (Zone Diameter Range in mm) |
Escherichia coli ATCC®a 35218b (H. influenzae
quality control) |
4/2 to 16/8 |
17 to 22 |
Haemophilus influenzae ATCC 49247 |
2/1 to 16/8 |
15 to 23 |
Streptococcus pneumoniae ATCC 49619 |
0.03/0.016 to 0.12/0.06 |
NA |
a ATCC is a trademark of the American
Type Culture Collection.
b When using Haemophilus Test Medium (HTM). |
Description of Clinical Studies
Two clinical studies were conducted in pediatric patients with acute otitis
media.
A non-comparative, open-label study assessed the bacteriologic and clinical
efficacy of AUGMENTIN ES-600 (90/6.4 mg/kg/day, divided every 12 hours) for
10 days in 521 pediatric patients (3 to 50 months) with acute otitis media.
The primary objective was to assess bacteriological response in children with
acute otitis media due to S. pneumoniae with amoxicillin/clavulanic acid
MICs of 4 mcg/mL. The study sought the enrollment of patients with the following
risk factors: Failure of antibiotic therapy for acute otitis media in the previous
3 months, history of recurrent episodes of acute otitis media, ≤ 2 years,
or daycare attendance. Prior to receiving AUGMENTIN ES-600, all patients had
tympanocentesis to obtain middle ear fluid for bacteriological evaluation. Patients
from whom S. pneumoniae (alone or in combination with other bacteria)
was isolated had a second tympanocentesis 4 to 6 days after the start of therapy.
Clinical assessments were planned for all patients during treatment (4-6 days
after starting therapy), as well as 2-4 days post-treatment and 15-18 days post-treatment.
Bacteriological success was defined as the absence of the pretreatment pathogen
from the on-therapy tympanocentesis specimen. Clinical success was defined as
improvement or resolution of signs and symptoms. Clinical failure was defined
as lack of improvement or worsening of signs and/or symptoms at any time following
at least 72 hours of AUGMENTN ES-600 (amoxicillin/clavulanate potassium); patients
who received an additional systemic antibacterial drug for otitis media after
3 days of therapy were considered clinical failures. Bacteriological eradication
on therapy (day 4-6 visit) in the per protocol population is summarized in Table
5.
Table 5: Bacteriologic Eradication Rates in the Per Protocol
Population
Pathogen |
Bacteriologic Eradication on Therapy |
n/N |
% |
95% CI a |
All S. pneumoniae |
121/123 |
98.4 |
(94.3, 99.8) |
S. pneumoniae with penicillin MIC = 2 mcg/mL |
19/19 |
100 |
(82.4, 100.0) |
S. pneumoniae with penicillin MIC = 4 mcg/mL |
12/14 |
85.7 |
(57.2, 98.2) |
H. influenzae |
75/81 |
92.6 |
(84.6, 97.2) |
M. catarrhalis |
11/11 |
100 |
(71.5, 100.0) |
a CI = confidence intervals; 95%
CIs are not adjusted for multiple comparisons. |
Clinical assessments were made in the per protocol population 2-4 days post-therapy
and 15-18 days post-therapy. Patients who responded to therapy 2-4 days post-therapy
were followed for 15-18 days post-therapy to assess them for acute otitis media.
Nonresponders at 2-4 days post-therapy were considered failures at the latter
timepoint.
Table 6: Clinical Assessments in the Per Protocol Population
(Includes S. pneumoniae Patients With Penicillin MICs = 2 or 4 mcg/mLa)
Pathogen |
2-4 Days Post-Therapy (Primary Endpoint) |
n/N |
% |
95% CI b |
All S. pneumoniae |
122/137 |
89.1 |
(82.6, 93.7) |
S. pneumoniae with penicillin MIC = 2 mcg/mL |
17/20 |
85.0 |
(62.1, 96.8) |
S. pneumoniae with penicillin MIC = 4 mcg/mL |
11/14 |
78.6 |
(49.2, 95.3) |
H. influenzae |
141/162 |
87.0 |
(80.9, 91.8) |
M. catarrhalis |
22/26 |
84.6 |
(65.1, 95.6) |
|
15-18 Days Post-Therapyc (Secondary
Endpoint) |
Pathogen |
n/N |
% |
95% CI † |
All S. pneumoniae |
95/136 |
69.9 |
(61.4, 77.4) |
S. pneumoniae with penicillin MIC = 2 mcg/mL |
11/20 |
55.0 |
(31.5, 76.9) |
S. pneumoniae with penicillin MIC = 4 mcg/mL |
5/14 |
35.7 |
(12.8, 64.9) |
H. influenzae |
106/156 |
67.9 |
(60.0, 75.2) |
M. catarrhalis |
14/25 |
56.0 |
(34.9, 75.6) |
a S. pneumoniae strains
with penicillin MICs of 2 or 4 mcg/mL are considered resistant to penicillin.
b CI = confidence intervals; 95% CIs are not adjusted for multiple
comparisons.
c Clinical assessments at 15-18 days post-therapy may have
been confounded by viral infections and new episodes of acute otitis media
with time elapsed post-treatment. |
In the intent-to-treat analysis, overall clinical outcomes at 2-4 days and
15-18 days post-treatment in patients with S. pneumoniae with penicillin
MIC = 2 mcg/mL and 4 mcg/mL were 29/41 (71%) and 17/41 (41.5%), respectively.
In the intent-to-treat population of 521 patients, the most frequently reported
adverse events were vomiting (6.9%), fever (6.1%), contact dermatitis (i.e.,
diaper rash) (6.1%), upper respiratory tract infection (4.0%), and diarrhea
(3.8%). Protocol-defined diarrhea (i.e., 3 or more watery stools in one day
or 2 watery stools per day for 2 consecutive days as recorded on diary cards)
occurred in 12.9% of patients.
A double-blind, randomized, clinical study compared AUGMENTIN ES-600 (90/6.4
mg/kg/day, divided every 12 hours) to AUGMENTIN (45/6.4 mg/kg/day, divided every
12 hours) for 10 days in 450 pediatric patients (3 months to 12 years) with
acute otitis media. The primary objective of the study was to compare the safety
of AUGMENTIN ES-600 to AUGMENTIN. There was no statistically significant difference
between treatments in the proportion of patients with 1 or more adverse events.
The most frequently reported adverse events for AUGMENTIN ES-600 and the comparator
of AUGMENTIN were coughing (11.9% versus 6.8%), vomiting (6.5% versus 7.7%),
contact dermatitis (i.e., diaper rash, 6.0% versus 4.8%), fever (5.5% versus
3.9%), and upper respiratory infection (3.0% versus 9.2%), respectively. The
frequencies of protocol-defined diarrhea with AUGMENTIN ES-600 (11.1%) and AUGMENTIN
(9.4%) were similar (95% confidence interval on difference: -4.2% to 7.7%).
Only 2 patients in the group treated with AUGMENTIN ES-600 and 1 patient in
the group treated with AUGMENTIN were withdrawn due to diarrhea.
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