The pharmacokinetic data were derived from the capsule
formulation; however, bioequivalence has been demonstrated for the oral
solution, capsule, tablet, and suspension formulations under fasting
conditions.
Following oral administration of cefprozil to fasting subjects, approximately
95% of the dose was absorbed. The average plasma half-life in normal subjects
was 1.3 hours, while the steady-state volume of distribution was estimated to be
0.23 L/kg. The total body clearance and renal clearance rates were approximately
3 mL/min/kg and 2.3 mL/min/kg, respectively.
Average peak plasma concentrations after administration of 250 mg, 500 mg, or
1 g doses of cefprozil to fasting subjects were approximately 6.1, 10.5, and
18.3 mcg/mL, respectively, and were obtained within 1.5 hours after dosing.
Urinary recovery accounted for approximately 60% of the administered dose. (See
Table.)
| Dosage (mg)
| Mean Plasma Cefprozil | 8 hour Urinary Excretion (%) |
| Concentrations (mcg/mL)* |
|
| Peak appx.
|
|
| 1.5 h | 4 h | 8 h |
|
| 250 mg | 6.1 | 1.7 | 0.2 | 60% |
| 500 mg | 10.5 | 3.2 | 0.4 | 62% |
| 1000 mg | 18.3 | 8.4 | 1.0 | 54% |
*Data represent mean values of 12 healthy volunteers.
During the first 4 hour period after drug administration, the average urine
concentrations following 250 mg, 500 mg, and 1 g doses were approximately 700
mcg/mL, 1000 mcg/mL, and 2900 mcg/mL, respectively.
Administration of cefprozil with food did not affect the extent of absorption
(AUC) or the peak plasma concentration (Cmax) of
cefprozil. However, there was an increase of 0.25 to 0.75 hours in the time to
maximum plasma concentration of cefprozil (Tmax).
The bioavailability of the capsule formulation of cefprozil was not affected
when administered 5 minutes following an antacid.
Plasma protein binding is approximately 36% and is independent of
concentration in the range of 2 mcg/mL to 20 mcg/mL.
There was no evidence of accumulation of cefprozil in the plasma in
individuals with normal renal function following multiple oral doses of up to
1000 mg every 8 hours for 10 days.
In patients with reduced renal function, the plasma half-life may be
prolonged up to 5.2 hours depending on the degree of the renal dysfunction. In
patients with complete absence of renal function, the plasma half-life of
cefprozil has been shown to be as long as 5.9 hours. The half-life is shortened
during hemodialysis. Excretion pathways in patients with markedly impaired renal
function have not been determined. (See PRECAUTIONS and DOSAGE AND ADMINISTRATION.)
In patients with impaired hepatic function, the half-life increases to
approximately 2 hours. The magnitude of the changes does not warrant a dosage
adjustment for patients with impaired hepatic function.
Healthy geriatric volunteers (≥65years old) who received a single 1 g dose of
cefprozil had 35% to 60% higher AUC and 40% lower renal clearance values
compared with healthy adult volunteers 20 to 40 years of age. The average AUC in
young and elderly female subjects was approximately 15% to 20% higher than in
young and elderly male subjects. The magnitude of these age- and gender-related
changes in the pharmacokinetics of cefprozil is not sufficient to necessitate
dosage adjustments.
Adequate data on CSF levels of cefprozil are not available.
Comparable pharmacokinetic parameters of cefprozil are observed between
pediatric patients (6 months to 12 years) and adults following oral
administration of selected matched doses. The maximum concentrations are
achieved at 1to 2 hours after dosing. The plasma elimination half-life is
approximately 1.5 hours. In general, the observed plasma concentrations of
cefprozil in pediatric patients at the 7.5, 15, and 30 mg/kg doses are similar
to those observed within the same time frame in normal adult subjects at the
250, 500, and 1000 mg doses, respectively. The comparative plasma concentrations
of cefprozil in pediatric patients and adult subjects at the equivalent dose
level are presented in the table below.
| Mean (SD) Plasma Cefprozil |
| Concentrations (mcg/mL) |
| Population | Dose | 1 h | 2 h | 4 h | 6 h | T½ (h) |
| children | 7.5 mg/kg | 4.70 | 3.99 | 0.91 | 0.23 a | 0.94 |
| (n=18) |
| (1.57) | (1.24) | (0.30) | (0.13) | (0.32) |
| adults | 250 mg | 4.82 | 4.92 | 1.70b | 0.53 | 1.28 |
| (n=12) |
| (2.13) | (1.13) | (0.53) | (0.17) | (0.34) |
| children | 15 mg/kg | 10.86 | 8.47 | 2.75 | 0.61c | 1.24 |
| (n=19) |
| (2.55) | (2.03) | (1.07) | (0.27) | (0.43) |
| adults | 500 mg | 8.39 | 9.42 | 3.18d | 1.00d | 1.29 |
| (n=12) |
| (1.95) | (0.98) | (0.76) | (0.24) | (0.14) |
| children | 30 mg/kg | 16.69 | 17.61 | 8.66 | -- | 2.06 |
| (n=10) |
| (4.26) | (6.39) | (2.70) |
| (0.21) |
| adults | 1000 mg | 11.99 | 16.95 | 8.36 | 2.79 | 1.27 |
| (n=12) |
| (4.67) | (4.07) | (4.13) | (1.77) | (0.12) |
an=11
bn=5
cn=9
dn=11
Microbiology:
Cefprozil has in vitro activity
against a broad range of gram-positive and gram-negative bacteria. The
bactericidal action of cefprozil results from inhibition of cell-wall synthesis.
Cefprozil 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.
Aerobic Gram-Positive Microorganisms:
Staphylococcus aureus
(including ß-lactamase-producing strains)
NOTE: Cefprozil is inactive against
methicillin-resistant staphylococci.
Streptococcus pneumoniae
Streptococcus pyogenes
Aerobic Gram-Negative Microorganisms:
Haemophilus influenzae
(including ß-lactamase-producing strains)
Moraxella (Branhamella) catarrhalis
(including ß-lactamase-producing strains)
The following in vitro data are available;
however, their clinical significance is unknown. Cefprozil exhibits in vitro minimum inhibitory concentrations (MICs) of 8
mcg/mL or less against most (≥90%) strains of the following microorganisms;
however, the safety and effectiveness of cefprozil in treating clinical
infections due to these microorganisms have not been established in adequate and
well-controlled clinical trials.
Aerobic Gram-Positive Microorganisms:
Enterococcus durans
Enterococcus faecalis
Listeria monocytogenes
Staphylococcus epidermidis
Staphylococcus saprophyticus
Staphylococcus warneri
Streptococcus agalactiae
Streptococci (Groups C, D, F, and G)
viridans group Streptococci
NOTE: Cefprozil is inactive against Enterococcus faecium.
Aerobic Gram-Negative Microorganisms:
Citrobacter diversus
Escherichia coli
Klebsiella pneumoniae
Neisseria gonorrhoeae
(including ß-lactamase-producing strains)
Proteus mirabilis
Salmonella spp.
Shigella spp .
Vibrio spp.
NOTE: Cefprozil is inactive against most strains of
Acinetobacter, Enterobacter, Morganella morganii, Proteus
vulgaris, Providencia, Pseudomonas, and Serratia.
Anaerobic Microorganisms:
Prevotella (Bacteroides)
melaninogenicus
Clostridium difficile
Clostridium perfringens
Fusobacterium spp.
Peptostreptococcus spp.
Propionibacterium acnes
NOTE: Most strains of the Bacteroides fragilis group are resistant to
cefprozil.
Susceptibility Tests:
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 procedure. Standardized procedures are based on
a dilution method1,2 (broth or agar) or equivalent with
standardized inoculum concentrations and standardized concentrations of
cefprozil powder. The MIC values should be interpreted according to the
following criteria:
MIC (mcg/mL) | Interpretation
|
| ≤8 | Susceptible (S) |
| 16 | Intermediate (I) |
| ≥32 | Resistant (R) |
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 which 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 cefprozil powder should provide the following MIC
values:
Microorganism
| MIC (mcg/mL)
|
Enterococcus faecalis ATCC 29212 | 4-16 |
Escherichia coli ATCC 25922
| 1-4 |
Haemophilus influenzae ATCC 49766 | 1-4 |
Staphylococcus aureus ATCC 29213 | 0.25-1
|
Streptococcus pneumoniae ATCC 49619 | 0.25-1
|
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 procedure3
requires the use of standardized inoculum concentrations. This procedure uses
paper disks impregnated with 30 mcg cefprozil to test the susceptibility of
microorganisms to cefprozil.
Reports from the laboratory providing results of the standard single-disk
susceptibility test with a 30 mcg cefprozil disk should be interpreted according
to the following criteria:
Zone diameter (mm) | Interpretation
|
| ≥18 | Susceptible (S) |
| 15-17 | Intermediate (I) |
| ≤14 | Resistant (R) |
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 cefprozil.
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 30 mcg
cefprozil disk should provide the following zone diameters in these laboratory
test quality control strains.
Microorganism
| Zone diameter (mm)
|
Escherichia coli ATCC 25922
| 21-27 |
Haemophilus influenzae ATCC 49766 | 20-27 |
Staphylococcus aureus ATCC 25923 | 27-33 |
Streptococcus pneumoniae ATCC 49619 | 25-32
|