CLINICAL PHARMACOLOGY
Average plasma concentrations of ceftriaxone following a
single 30-minute intravenous (IV) infusion of a 0.5, 1 or 2 g dose and
intramuscular (IM) administration of a single 0.5 (250 mg/mL or 350 mg/mL concentrations)
or 1 g dose in healthy subjects are presented in Table 1.
TABLE 1. Ceftriaxone Plasma Concentrations After
Single Dose Administration
Dose/Route |
Average Plasma Concentrations (mcg/mL) |
0.5 hr |
1 hr |
2 hr |
4 hr |
6 hr |
8 hr |
12 hr |
16 hr |
24 hr |
0.5 g IV* |
82 |
59 |
48 |
37 |
29 |
23 |
15 |
10 |
5 |
0.5 g IM 250 mg/mL |
22 |
33 |
38 |
35 |
30 |
26 |
16 |
ND |
5 |
0.5 g IM 350 mg/mL |
20 |
32 |
38 |
34 |
31 |
24 |
16 |
ND |
5 |
1 g IV* |
151 |
111 |
88 |
67 |
53 |
43 |
28 |
18 |
9 |
1 g IM |
40 |
68 |
76 |
68 |
56 |
44 |
29 |
ND |
ND |
2 g IV* |
257 |
192 |
154 |
117 |
89 |
74 |
46 |
31 |
15 |
ND = Not determined
* IVÂ doses were infused at a constant rate over 30 minutes |
Ceftriaxone was completely absorbed following IM
administration with mean maximum plasma concentrations occurring between 2 and
3 hours post-dose. Multiple IV or IM doses ranging from 0.5 to 2 g at 12- to
24-hour intervals resulted in 15% to 36% accumulation of ceftriaxone above
single dose values.
Ceftriaxone concentrations in urine are shown in Table 2.
TABLE 2: Urinary Concentrations of Ceftriaxone After
Single Dose Administration
Dose/Route |
Average Urinary Concentrations (mcg/mL) |
0 to2 hr |
2 to 4 hr |
4 to8 hr |
8 to12 hr |
12 to 24 hr |
24 to 48 hr |
0.5 g IV |
526 |
366 |
142 |
87 |
70 |
15 |
0.5 g IM |
115 |
425 |
308 |
127 |
96 |
28 |
1 g IV |
995 |
855 |
293 |
147 |
132 |
32 |
1 g IM |
504 |
628 |
418 |
237 |
ND |
ND |
2 g IV |
2692 |
1976 |
757 |
274 |
198 |
40 |
ND = Not determined |
Thirty-three percent to 67% of a ceftriaxone dose was
excreted in the urine as unchanged drug and the remainder was secreted in the
bile and ultimately found in the feces as microbiologically inactive compounds.
After a 1 g IV dose, average concentrations of ceftriaxone, determined from 1
to 3 hours after dosing, were 581 mcg/mL in the gallbladder bile, 788 mcg/mL in
the common duct bile, 898 mcg/mL in the cystic duct bile, 78.2 mcg/g in the
gallbladder wall and 62.1 mcg/mL in the concurrent plasma.
Over a 0.15 to 3 g dose range in healthy adult subjects,
the values of elimination half-life ranged from 5.8 to 8.7 hours; apparent
volume of distribution from 5.78 to 13.5 L; plasma clearance from 0.58 to 1.45
L/hour; and renal clearance from 0.32 to 0.73 L/hour. Ceftriaxone is reversibly
bound to human plasma proteins, and the binding decreased from a value of 95%
bound at plasma concentrations of <25 mcg/mL to a value of 85% bound at 300
mcg/mL Ceftriaxone crosses the blood placenta barrier.
The average values of maximum plasma concentration,
elimination half-life, plasma clearance and volume of distribution after a 50
mg/kg IV dose and after a 75 mg/kg IV dose in pediatric patients suffering from
bacterial meningitis are shown in Table 3. Ceftriaxone penetrated the inflamed
meninges of infants and pediatric patients; CSF concentrations after a 50 mg/kg
IV dose and after a 75 mg/kg IV dose are also shown in Table 3.
TABLE 3: Average Pharmacokinetic Parameters of
Ceftriaxone in Pediatric Patients With Meningitis
|
50 mg/kg IV |
75 mg/kg IV |
Maximum Plasma Concentration (mcg/mL) |
216 |
275 |
Elimination Half-life (hr) |
4.6 |
4.3 |
Plasma Clearance (mL/hr/kg) |
49 |
60 |
Volume of Distribution (mL/kg) |
338 |
373 |
CSF Concentration-inflamed meninges (mcg/mL) |
5.6 |
6.4 |
Range (mcg/mL) |
1.3 to18.5 |
1.3to 44 |
Time after dose (hr) |
3.7 (±1.6) |
3.3 (±1.4) |
Compared to that in healthy adult subjects, the
pharmacokinetics of ceftriaxone were only minimally altered in elderly subjects
and in patients with renal impairment or hepatic dysfunction (Table 4); therefore,
dosage adjustments are not necessary for these patients with ceftriaxone
dosages up to 2 g per day. Ceftriaxone was not removed to any significant
extent from the plasma by hemodialysis. In 6 of 26 dialysis patients, the
elimination rate of ceftriaxone was markedly reduced.
TABLE 4: Average Pharmacokinetic Parameters of
Ceftriaxone in Humans
Subject Group |
Elimination Half-Life (hr) |
Plasma Clearance (L/hr) |
Volume of Distribution (L) |
Healthy Subjects |
5.8 to 8.7 |
0.58 to 1.45 |
5.8 to13.5 |
Elderly Subjects (mean age, 70.5 yr) Patients With Renal Impairment |
8.9 |
0.83 |
10.7 |
Hemodialysis Patients (0 to 5 mL/min)* |
14.7 |
0.65 |
13.7 |
Severe (5 to15 mL/min) |
15.7 |
0.56 |
12.5 |
Moderate (16 to 30 mL/min) |
11.4 |
0.72 |
11.8 |
Mild (31 to 60 mL/min) |
12.4 |
0.70 |
13.3 |
Patients With Liver Disease |
8.8 |
1.1 |
13.6 |
* Creatinine clearance. |
The elimination of ceftriaxone is not altered when
ceftriaxone is co-administered with probenecid.
Pharmacokinetics In The Middle Ear Fluid
In one study, total ceftriaxone concentrations (bound and
unbound) were measured in middle ear fluid obtained during the insertion of
tympanostomy tubes in 42 pediatric patients with otitis media. Sampling times
were from 1 to 50 hours after a single intramuscular injection of 50 mg/kg of
ceftriaxone. Mean (±SD) ceftriaxone levels in the middle ear reached a peak of
35 (±12) mcg/mL at 24 hours, and remained at 19 (±7) mcg/mL at 48 hours. Based
on middle ear fluid ceftriaxone concentrations in the 23 to 25 hour and the 46
to 50 hour sampling time intervals, a half-life of 25 hours was calculated.
Ceftriaxone is highly bound to plasma proteins. The extent of binding to
proteins in the middle ear fluid is unknown.
Interaction With Calcium
Two in vitro studies, one using adult plasma and the
other neonatal plasma from umbilical cord blood have been carried out to assess
interaction of ceftriaxone and calcium. Ceftriaxone concentrations up to 1 mM
(in excess of concentrations achieved in vivo following administration of 2 g
ceftriaxone infused over 30 minutes) were used in combination with calcium
concentrations up to 12 mM (48 mg/dL). Recovery of ceftriaxone from plasma was
reduced with calcium concentrations of 6 mM (24 mg/dL) or higher in adult
plasma or 4 mM (16 mg/dL) or higher in neonatal plasma. This may be reflective
of ceftriaxone-calcium precipitation.
Microbiology
Mechanism Of Action
Ceftriaxone is a bactericidal agent that acts by
inhibition of bacterial cell wall synthesis. Ceftriaxone has activity in the
presence of some beta-lactamases, both penicillinases and cephalosporinases, of
Gram-negative and Gram-positive bacteria.
Mechanism Of Resistance
Resistance to ceftriaxone is primarily through hydrolysis
by beta-lactamase, alterations of penicillinbinding proteins (PBPs), and
decreased permeability.
Interaction With Other Antimicrobials
In an in vitro study antagonistic effects have been
observed with the combination of chloramphenicol and ceftriaxone.
Ceftriaxone has been shown to be active against most
strains of the following bacteria, both in vitro and in clinical infections
described in the INDICATIONS AND USAGE section:
Gram Negative Bacteria
Acinetobacter calcoaceticus
Enterobacter aerogenes
Enterobacter cloacae
Escherichia coli
Haemophilus influenzae
Haemophilus parainfluenzae
Klebsiella oxytoca
Klebsiella pneumoniae
Moraxella catarrhalis
Morganella morganii
Neisseria gonorrhoeae
Neisseria meningitidis
Proteus mirabilis
Proteus vulgaris
Pseudomonas aeruginosa
Serratia marcescens
Gram-Positive Bacteria
Staphylococcus aureus
Staphylococcus epidermidis
Streptococcus pneumoniae
Streptococcus pyogenes
Viridans group streptococci
Anaerobic Bacteria
Bacteroides fragilis
Clostridium species
Peptostreptococcus species
The following in vitro data are available, but their
clinical s ignificance is unknown. At least 90 percent of the following
microorganisms exhibit an in-vitro minimum inhibitory concentration (MIC) less than
or equal to the susceptible breakpoint for ceftriaxone. However, the efficacy
of ceftriaxone in treating clinical infections due to these microorganisms has
not been established in adequate and wellcontrolled clinical trails.
Gram-Negative Bacteria
Citrobacter diversus
Citrobacter freundii
Providencia species (including Providencia
rettgeri)
Salmonella species (including Salmonella typhi)
Shigella species
Gram-Positive Bacteria
Streptococcus agalactiae
Anaerobic Bacteria
Porphyromonas (Bacteroides) melaninogenicus
Prevotella (Bacteroides) bivius
Susceptibility Test Methods
When available, the clinical microbiology laboratory
should provide the results of in vitro susceptibility test results for
antimicrobial drug products used in resident hospitals 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 product for treatment.
Dilution Techniques
Quantitative methods are used to determine antimicrobial
minimal inhibitory concentrations (MICs). These MICs provide estimates of the
susceptibility of bacteria to antimicrobial compounds. The MICs should be
determined using a standardized test method1,3. The MIC values
should be interpreted according to criteria provided in Table 5.
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 provides an estimate of the susceptibility
of bacteria to antimicrobial compounds. The zone size should be determined
using a standardized test method2,3. This procedure uses paper disks
impregnated with 30 mcg ceftriaxone to test the susceptibility of
microorganisms to ceftriaxone. The disk diffusion interpretive criteria are provided
in Table 5.
Anaerobic Techniques
For anaerobic bacteria, the susceptibility to ceftriaxone
as MICs can be determined by a standardized agar test method. The MIC values
obtained should be interpreted according to the criteria provided in Table 5.
Table 5: Susceptibility Test Interpretive Criteria for
Ceftriaxone.
Pathogen |
Minimum Inhibitory Concentrations (mcg/ml) |
Disk Diffusion Zone Diameters (mm) |
(S) Susceptible |
(I) Intermediate |
(R) Resistant |
(S) Susceptible |
(I) Intermediate |
(R) Resistant |
Enterobacteriaceae |
≤1 |
2 |
≥4 |
≥23 |
20 to 22 |
≤19 |
Haemophilus influenzaea |
≤2 |
- |
- |
≥26 |
- |
- |
Neisseria gonorrhoeaea |
≤0.25 |
- |
- |
≥35 |
- |
- |
Neisseria meningitidisa |
≤0.12 |
- |
- |
≥34 |
- |
- |
Streptococcus Pneumoniaeb meningitis isolates |
≤0.5 |
1 |
≥2 |
- |
- |
- |
Streptococcus pneumoniaeb non-meningitis isolates |
≤1 |
2 |
≥4 |
- |
- |
- |
Streptococcus species beta-hemolytic groupa |
≤0.5 |
- |
- |
≥24 |
- |
- |
Viridians group streptococci |
≤1 |
2 |
≥4 |
≥27 |
25 to 26 |
≤24 |
Anaerobic bacteria (agar method) |
≤16 |
32 |
≥64 |
- |
- |
- |
Susceptibility of staphylococci to ceftriaxone may be
deduced from testing only penicillin and either cefoxitin or oxacillin.
a The current absence of data on resistant isolates precludes
defining any category other than 'Susceptible'. If isolates yield MIC results
other than susceptible, they should be submitted to a reference laboratory for
additional testing.
b Disc diffusion interpretive criteria for ceftriaxone discs against
Streptococcus pneumoniae are not available, however, isolates of pneumococci
with oxacillin zone diameters of ≥ 20 mm are susceptible (MIC≤0.06
mcg/mL) to penicillin and can be considered susceptible to ceftriaxone. Streptococcus
pneumoniae isolates should not be reported as penicillin (ceftriaxone)
resistant or intermediate based solely on an oxacillin zone diameter of ≤
19 mm. The ceftriaxone MIC should be determined for those isolates with
oxacillin zone diameters ≤ 19 mm. |
A report of Susceptible indicates that the antimicrobial
is likely to inhibit growth of the pathogen if the antimicrobial compound
reaches the concentration at the infection site necessary to inhibit growth of
the pathogen. 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 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 indicates that the antimicrobial is not
likely to inhibit growth of the pathogen if the antimicrobial compound reaches
the concentrations usually achievable at the infection site; 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 individual
performing the test1,2,3,4. Standard ceftriaxone powder should
provide the following range of MIC values noted in Table 6. For the diffusion
technique using the 30 mcg disk, the criteria in Table 6 should be achieved.
Table 6: Acceptable Quality Control Ranges for
Ceftriaxone
QC Strain |
Minimum Inhibitory Concentrations (mcg/ml) |
Disk Diffusion Zone Diameters (mm) |
Escherichia coli ATCC 25922 |
0.03 to 0.12 |
29 to 35 |
Staphylococcus aureus ATCC 25923 |
- |
22 to 28 |
Staphylococcus aureus ATCC 29213 |
1to 8 |
- |
Haemophilus influenzae ATCC 49247 |
0.06 to 0.25 |
31 to 39 |
Neisseria gonorrhoeae ATCC 49226 |
0.004 to 0.015 |
39 to 51 |
Pseudomonas aeruginosa ATCC 27853 |
8 to 64 |
17 to 23 |
Streptococcus pneumoniae ATCC 49619 |
0.03 to 0.12 |
30 to 35 |
Bacteroides fragilis ATCC 25285 (agar method) |
32 to 128 |
- |
Bacteroides thetaiotamicron ATCC 29741 (aaar method) |
64 to 256 |
- |
ATCC® is a
registered trademark of the American Type Culture Collection. |
Animal Pharmacology
Concretions consisting of the precipitated calcium salt
of ceftriaxone have been found in the gallbladder bile of dogs and baboons
treated with ceftriaxone.
These appeared as gritty sediment in dogs that received
100 mg/kg/day for 4 weeks. A similar phenomenon has been observed in baboons
but only after a protracted dosing period (6 months) at higher dose levels (335
mg/kg/day or more). The likelihood of this occurrence in humans is considered to
be low, since ceftriaxone has a greater plasma half-life in humans, the calcium
salt of ceftriaxone is more soluble in human gallbladder bile and the calcium
content of human gallbladder bile is relatively low.
Clinical Studies
Clinical Trials in Pediatric Patients With Acute
Bacterial Otitis Media: In two adequate and well-controlled U.S. clinical
trials a single IM dose of ceftriaxone was compared with a 10 day course of
oral antibiotic in pediatric patients between the ages of 3 months and 6 years.
The clinical cure rates and statistical outcome appear in the table below:
Study Day |
Clinical Efficacy in Evaluable Population |
Ceftriaxone Single Dose |
Comparator - 10 Days of Oral Therapy |
95% Confidence Interval |
Statistical Outcome |
Study 1-U.S. |
amoxicillin/clavulanate |
Ceftriaxone is lower than control at study day 14 and 28. |
14 |
74% (220/296) |
82% (247/302) |
(-14.4%, -0.5%) |
28 |
58% (167/288) |
67% (200/297) |
(-17.5%, -1.2%) |
Study 2-U.S.5 |
|
TMP-SMZ |
|
Ceftriaxone is equivalent to control at study day 14 and 28. |
14 |
54% (113/210) |
60% (124/206) |
(-16.4%, 3.6%) |
28 |
35% (73/206) |
45% (93/205) |
(-19.9%, 0.0%) |
An open-label bacteriologic study of ceftriaxone without
a comparator enrolled 108 pediatric patients, 79 of whom had positive baseline
cultures for one or more of the common pathogens. The results of this study are
tabulated as follows:
Week 2 and 4 Bacteriologic Eradication Rates in the Per
Protocol Analysis in the Roche Bacteriologic Study by pathogen:
Organism |
Study Day 13 to 15 |
Study Day 30+2 |
No. Analyzed |
No. Erad. (%) |
No. Analyzed |
No. Erad. (%) |
Streptococcus pneumoniae |
38 |
32 (84) |
35 |
25 (71) |
Haemophilus influenzae |
33 |
28 (85) |
31 |
22 (71) |
Moraxella catarrhalis |
15 |
12 (80) |
15 |
9 (60) |
REFERENCES
1. Clinical and Laboratory Standards Institute (CLSI). Methods
for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow
Aerobically; Approved Standard to Ninth Edition. CLSI document M07- A9,
Clinical and Laboratory Standards Institute, 950 West Valley Road, Suite 2500,
Wayne, Pennsylvania 19087, USA, 2012.
2. Clinical and Laboratory Standards Institute (CLSI). Performance
Standards for Antimicrobial Susceptibility Testing; Twenty-third Informational
Supplement, CLSI document M100-S23. CLSI document M100-S23, Clinical and
Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne,
Pennsylvania 19087, USA, 2013.
3. Clinical and Laboratory Standards Institute (CLSI). Performance
Standards for Antimicrobial Disk Susceptibility Tests; Approved Standard to
Eleventh Edition CLSI document M02-A11, Clinical and Laboratory Standards
Institute, 950 West Valley Road, Suite 2500, Wayne, Pennsylvania 19087, USA,
2012.
4. Clinical and Laboratory Standards Institute (CLSI). Methods
for Antimicrobial Susceptibility Testing of Anaerobic Bacteria; Approved
Standard to Eight Edition. CLSI document M11-A8. Clinical and Laboratory
Standards Institute, 950 West Valley Road, Suite 2500, Wayne, PA 19087 USA,
2012
5. Barnett ED, Teele DW, Klein JO, et al. Comparison of
Ceftriaxone and Trimethoprim- Sulfamethoxazole for Acute Otitis Media. Pediatrics.
Vol. 99, No. 1, January 1997.