CLINICAL PHARMACOLOGY
Mechanism Of Action
Daptomycin is an antibacterial
drug [see Microbiology].
Pharmacodynamics
Based on animal models of
infection, the antimicrobial activity of daptomycin appears to correlate with
the AUC/MIC (area under the concentration-time curve/minimum inhibitory
concentration) ratio for certain pathogens, including S. aureus. The
principal pharmacokinetic/pharmacodynamic parameter best associated with
clinical and microbiological cure has not been elucidated in clinical trials
with CUBICIN RF.
Pharmacokinetics
CUBICIN Administered Over A 30-Minute
Period In Adults
The mean and standard deviation
(SD) pharmacokinetic parameters of daptomycin at steady-state following
intravenous (IV) administration of CUBICIN over a 30-minute period at 4 to 12
mg/kg q24h to healthy young adults are summarized in Table 12.
Table 12: Mean (SD)
Daptomycin Pharmacokinetic Parameters in Healthy Adult Volunteers at
Steady-State
Dose*† (mg/kg) |
Pharmacokinetic Parameters‡ |
AUC0-24 (mcg•h/mL) |
t½ (h) |
Vss (L/kg) |
CLT (mL/h/kg) |
Cmax (mcg/mL) |
4 (N=6) |
494 (75) |
8.1 (1.0) |
0.096 (0.009) |
8.3 (1.3) |
57.8 (3.0) |
6 (N=6) |
632 (78) |
7.9 (1.0) |
0.101 (0.007) |
9.1 (1.5) |
93.9 (6.0) |
8 (N=6) |
858 (213) |
8.3 (2.2) |
0.101 (0.013) |
9.0 (3.0) |
123.3 (16.0) |
10 (N=9) |
1039 (178) |
7.9 (0.6) |
0.098 (0.017) |
8.8 (2.2) |
141.1 (24.0) |
12 (N=9) |
1277 (253) |
7.7 (1.1) |
0.097 (0.018) |
9.0 (2.8) |
183.7 (25.0) |
*CUBICIN was administered by IV
infusion over a 30-minute period.
†Doses of CUBICIN in excess of 6 mg/kg have not been approved.
‡AUC0-24, area under the concentration-time curve from 0 to 24 hours; t½,
elimination half-life; Vss, volume of distribution at steady-state; CLT, total
plasma clearance; Cmax, maximum plasma concentration. |
Daptomycin pharmacokinetics
were generally linear and time-independent at CUBICIN doses of 4 to 12 mg/kg
q24h administered by IV infusion over a 30-minute period for up to 14 days.
Steady-state trough concentrations were achieved by the third daily dose. The
mean (SD) steady-state trough concentrations attained following the
administration of 4, 6, 8, 10, and 12 mg/kg q24h were 5.9 (1.6), 6.7 (1.6),
10.3 (5.5), 12.9 (2.9), and 13.7 (5.2) mcg/mL, respectively.
CUBICIN Administered Over A 2-Minute
Period In Adults
Following IV administration of
CUBICIN over a 2-minute period to healthy adult volunteers at doses of 4 mg/kg
(N=8) and 6 mg/kg (N=12), the mean (SD) steady-state systemic exposure (AUC)
values were 475 (71) and 701 (82) mcg•h/mL, respectively. Values for maximum
plasma concentration (Cmax) at the end of the 2-minute period could not be
determined adequately in this study. However, using pharmacokinetic parameters
from 14 healthy adult volunteers who received a single dose of CUBICIN 6 mg/kg
IV administered over a 30-minute period in a separate study, steady-state Cmax values
were simulated for CUBICIN 4 and 6 mg/kg IV administered over a 2-minute
period. The simulated mean (SD) steady-state Cmax values were 77.7 (8.1) and
116.6 (12.2) mcg/mL, respectively.
Distribution
Daptomycin is reversibly bound
to human plasma proteins, primarily to serum albumin, in a
concentration-independent manner. The overall mean binding ranges from 90 to
93%.
In clinical studies, mean serum
protein binding in adult subjects with creatinine clearance (CLCR) ≥30
mL/min was comparable to that observed in healthy adult subjects with normal
renal function. However, there was a trend toward decreasing serum protein
binding among subjects with CLCR <30 mL/min (88%), including those receiving
hemodialysis (86%) and continuous ambulatory peritoneal dialysis (CAPD) (84%).
The protein binding of daptomycin in adult subjects with moderate hepatic
impairment (Child-Pugh Class B) was similar to that in healthy adult subjects.
The volume of distribution at
steady-state (Vss) of daptomycin in healthy adult subjects was approximately 0.1
L/kg and was independent of dose.
Metabolism
In in vitro studies, daptomycin
was not metabolized by human liver microsomes.
In 5 healthy adults after infusion of radiolabeled 14C-daptomycin,
the plasma total radioactivity was similar to the concentration determined by
microbiological assay. Inactive metabolites were detected in urine, as
determined by the difference between total radioactive concentrations and
microbiologically active concentrations. In a separate study, no metabolites
were observed in plasma on Day 1 following the administration of CUBICIN at 6
mg/kg to adult subjects. Minor amounts of three oxidative metabolites and one
unidentified compound were detected in urine. The site of metabolism has not
been identified.
Excretion
Daptomycin is excreted
primarily by the kidneys. In a mass balance study of 5 healthy adult subjects
using radiolabeled daptomycin, approximately 78% of the administered dose was
recovered from urine based on total radioactivity (approximately 52% of the
dose based on microbiologically active concentrations), and 5.7% of the
administered dose was recovered from feces (collected for up to 9 days) based
on total radioactivity.
Specific Populations
Renal Impairment
Population-derived
pharmacokinetic parameters were determined for infected adult patients
(complicated skin and skin structure infections [cSSSI] and S. aureus bacteremia)
and noninfected adult subjects with various degrees of renal function (Table
13). Total plasma clearance (CLT), elimination half-life (t½), and volume of
distribution at steady-state (Vss) in patients with cSSSI were similar to those
in patients with S. aureus bacteremia. Following administration of
CUBICIN 4 mg/kg q24h by IV infusion over a 30-minute period, the mean CLT was
9%, 22%, and 46% lower among subjects and patients with mild (CLCR 50 - 80
mL/min), moderate (CLCR 30 - <50 mL/min), and severe (CLCR <30 mL/min)
renal impairment, respectively, than in those with normal renal function (CLCR >80
mL/min). The mean steady-state systemic exposure (AUC), t½, and Vss increased
with decreasing renal function, although the mean AUC for patients with CLCR 30 - 80
mL/min was not markedly different from the mean AUC for patients with normal
renal function. The mean AUC for patients with CLCR <30 mL/min and for
patients on dialysis (CAPD and hemodialysis dosed post-dialysis) was
approximately 2 and 3 times higher, respectively, than for patients with normal
renal function. The mean Cmax ranged from 60 to 70 mcg/mL in patients with CLCR
≥30 mL/min, while the mean Cmax for patients with CLCR <30 mL/min
ranged from 41 to 58 mcg/mL. After administration of CUBICIN 6 mg/kg q24h by IV
infusion over a 30-minute period, the mean Cmax ranged from 80 to 114 mcg/mL in
patients with mild to moderate renal impairment and was similar to that of
patients with normal renal function.
Table 13: Mean (SD) Daptomycin Population
Pharmacokinetic Parameters Following Infusion of CUBICIN 4 mg/kg or 6 mg/kg to
Infected Adult Patients and Noninfected Adult Subjects with Various Degrees of
Renal Function
Renal Function |
Pharmacokinetic Parameters* |
t½† (h) 4 mg/kg |
Vss† (L/kg) 4 mg/kg |
CLT† (mL/h/kg) 4 mg/kg |
AUC0-∞† (mcg•h/mL) 4 mg/kg |
AUCss‡ (mcg•h/mL) 6 mg/kg |
Cmin.ss‡ (mcg/mL) 6 mg/kg |
Normal (CLCR >80 mL/min) |
9.39 (4.74) N=165 |
0.13 (0.05) N=165 |
10.9 (4.0) N=165 |
417 (155) N=165 |
545 (296) N=62 |
6.9 (3.5) N=61 |
Mild Renal Impairment (CLCR 5080 mL/min) |
10.75 (8.36) N=64 |
0.12 (0.05) N=64 |
9.9 (4.0) N=64 |
466 (177) N=64 |
637 (215) N=29 |
12.4 (5.6) N=29 |
Moderate Renal Impairment (CLCR 30-<50 mL/min) |
14.70 (10.50) N=24 |
0.15 (0.06) N=24 |
8.5 (3.4) N=24 |
560 (258) N=24 |
868 (349) N=15 |
19.0 (9.0) N=14 |
Severe Renal Impairment (CLCR <30 mL/min) |
27.83 (14.85) N=8 |
0.20 (0.15) N=8 |
5.9 (3.9) N=8 |
925 (467) N=8 |
1050 (892) N=2 |
24.4 (21.4) N=2 |
Hemodialysis |
30.51 (6.51) N=16 |
0.16 (0.04) N=16 |
3.9 (2.1) N=16 |
1193 (399) N=16 |
NA |
NA |
CAPD |
27.56 (4.53) N=5 |
0.11 (0.02) N=5 |
2.9 (0.4) N=5 |
1409 (238) N=5 |
NA |
NA |
Note: CUBICIN was administered
over a 30-minute period.
*CLCR, creatinine clearance estimated using the Cockcroft-Gault equation with
actual body weight; CAPD, continuous ambulatory peritoneal dialysis; AUC0-∞,
area under the concentration-time curve extrapolated to infinity; AUCss, area
under the concentration-time curve calculated over the 24-hour dosing interval
at steady-state; Cmin,ss, trough concentration at steady-state; NA, not
applicable.
†Parameters obtained following a single dose from patients with complicated
skin and skin structure infections and healthy subjects.
‡Parameters obtained at steady-state from patients with S. aureus bacteremia. |
Because renal excretion is the
primary route of elimination, adjustment of CUBICIN RF dosage interval is
necessary in adult patients with severe renal impairment (CLCR <30 mL/min) [see
DOSAGE AND ADMINISTRATION].
Hepatic Impairment
The pharmacokinetics of
daptomycin were evaluated in 10 adult subjects with moderate hepatic impairment
(Child-Pugh Class B) and compared with those in healthy adult volunteers (N=9)
matched for gender, age, and weight. The pharmacokinetics of daptomycin were
not altered in subjects with moderate hepatic impairment. No dosage adjustment
is warranted when CUBICIN RF is administered to patients with mild to moderate
hepatic impairment. The pharmacokinetics of daptomycin in patients with severe
hepatic impairment (Child-Pugh Class C) have not been evaluated.
Gender
No clinically significant
gender-related differences in daptomycin pharmacokinetics have been observed.
No dosage adjustment is warranted based on gender when CUBICIN RF is
administered.
Geriatric
The pharmacokinetics of
daptomycin were evaluated in 12 healthy elderly subjects (≥75 years of
age) and 11 healthy young adult controls (18 to 30 years of age). Following
administration of a single 4 mg/kg dose of CUBICIN by IV infusion over a
30-minute period, the mean total clearance of daptomycin was approximately 35%
lower and the mean AUC0-∞ was approximately 58% higher in elderly subjects than in
healthy young adult subjects. There were no differences in Cmax [see Use In Specific
Populations].
Obesity
The pharmacokinetics of daptomycin were evaluated in 6
moderately obese (Body Mass Index [BMI] 25 to 39.9 kg/m²) and 6 extremely obese
(BMI ≥40 kg/m²) adult subjects and controls matched for age, gender, and
renal function. Following administration of CUBICIN by IV infusion over a
30-minute period as a single 4 mg/kg dose based on total body weight, the total
plasma clearance of daptomycin normalized to total body weight was
approximately 15% lower in moderately obese subjects and 23% lower in extremely
obese subjects than in nonobese controls. The AUC0-∞ of daptomycin was
approximately 30% higher in moderately obese subjects and 31% higher in
extremely obese subjects than in nonobese controls. The differences were most
likely due to differences in the renal clearance of daptomycin. No adjustment
of CUBICIN RF dosage is warranted in obese patients.
Pediatric
The pharmacokinetics of
daptomycin in pediatric subjects was evaluated in 3 single-dose pharmacokinetic
studies. In general, body weight-normalized total body clearance in pediatric
patients was higher than in adults and increased with a decrease of age,
whereas elimination half-life tends to decrease with a decrease of age. Body
weight-normalized total body clearance and elimination half-life of daptomycin
in children 2 to 6 years of age were similar at different doses.
A study was conducted to assess
safety, efficacy, and pharmacokinetics of daptomycin in pediatric patients (1
to 17 years old, inclusive) with cSSSI caused by Gram-positive pathogens. Patients
were enrolled into 4 age groups [see Clinical Studies], and intravenous
CUBICIN doses of 5 to 10 mg/kg once daily were administered. Following
administration of multiple doses, daptomycin exposure (AUCss and Cmax,ss) was
similar across different age groups after dose adjustment based on body weight
and age (Table 14).
Table 14: Mean (SD) Daptomycin Population
Pharmacokinetic Parameters in cSSSI Pediatric Patients
Age |
Pharmacokinetic Parameters |
Dose (mg/kg) |
Infusion Duration (min) |
AUCss (mcg•h/mL) |
t½ (h) |
Vss (mL) |
CLT (mL/h/kg) |
Cmax,ss (mcg/mL) |
12 to 17 years (N=6) |
5 |
30 |
434 (67.9) |
7.1 (0.9) |
8200 (3250) |
11.8 (2.15) |
76.4 (6.75) |
7 to 11 years (N=2) |
7 |
30 |
543* |
6.8* |
4470* |
13.2* |
92.4* |
2 to 6 years (N=7) |
9 |
60 |
452 (93.1) |
4.6 (0.8) |
2750 (832) |
20.8 (4.29) |
90.3 (14.0) |
1 to less than 2 years (N=27) |
10 |
60 |
462 (138) |
4.8 (0.6) |
1670 (446) |
23.1 (5.43) |
81.6 (20.7) |
AUCss, area under the
concentration-time curve at steady state; CLT, clearance normalized to body
weight;
Vss, volume of distribution at steady state; t½, terminal half-life
*Mean is calculated from N=2 |
A study was conducted to assess
safety, efficacy, and pharmacokinetics of daptomycin in pediatric patients with
S. aureus bacteremia. Patients were enrolled into 3 age groups [see Clinical
Studies], and intravenous doses of 7 to 12 mg/kg once daily were
administered. Following administration of multiple doses, daptomycin exposure
(AUCss and Cmax,ss) was similar across different age groups after dose
adjustment based on body weight and age (Table 15).
Table 15: Mean (SD) of Daptomycin Pharmacokinetics in Bacteremia Pediatric Patients
Age |
Pharmacokinetic Parameters |
Dose (mg/kg) |
Infusion Duration (min) |
AUCss (mcg•h/mL) |
t½ (h) |
Vss (mL) |
CLT (mL/h/kg) |
Cmax,ss (mcg/mL) |
12 to 17 years (N=13) |
7 |
30 |
656 (334) |
7.5 (2.3) |
6420 (1980) |
12.4 (3.9) |
104 (35.5) |
7 to 11 years (N=19) |
9 |
30 |
579 (116) |
6.0 (0.8) |
4510 (1470) |
15.9 (2.8) |
104 (14.5) |
2 to 6 years (N=19) |
12 |
60 |
620 (109) |
5.1 (0.6) |
2200 (570) |
19.9 (3.4) |
106 (12.8) |
AUCss, area under the
concentration-time curve at steady state; CLT, clearance normalized to body
weight; Vss, volume of distribution at steady state; t½, terminal half-life |
No patients 1 to <2 years of
age were enrolled in the study. Simulation using a population pharmacokinetic
model demonstrated that the AUCss of daptomycin in pediatric patients 1 to
<2 years of age receiving 12 mg/kg once daily would be comparable to that in
adult patients receiving 6 mg/kg once daily.
Drug-Drug Interactions
In Vitro Studies
In vitro studies with human hepatocytes indicate that daptomycin
does not inhibit or induce the activities of the following human cytochrome
P450 isoforms: 1A2, 2A6, 2C9, 2C19, 2D6, 2E1, and 3A4. It is unlikely that
daptomycin will inhibit or induce the metabolism of drugs metabolized by the P450
system.
Aztreonam
In a study in which 15 healthy
adult subjects received a single dose of CUBICIN 6 mg/kg IV and a combination
dose of CUBICIN 6 mg/kg IV and aztreonam 1 g IV, administered over a 30-minute
period, the Cmax and AUC0-∞ of daptomycin were not significantly altered by aztreonam.
Tobramycin
In a study in which 6 healthy
adult males received a single dose of CUBICIN 2 mg/kg IV, tobramycin 1 mg/kg
IV, and both in combination, administered over a 30-minute period, the mean Cmax
and AUC0-∞ of daptomycin were 12.7% and 8.7% higher, respectively,
when CUBICIN was coadministered with tobramycin. The mean Cmax and AUC0-∞ of tobramycin
were 10.7% and 6.6% lower, respectively, when tobramycin was coadministered
with CUBICIN. These differences were not statistically significant. The
interaction between daptomycin and tobramycin with a clinical dose of CUBICIN
RF is unknown.
Warfarin
In 16 healthy adult subjects,
administration of CUBICIN 6 mg/kg q24h by IV infusion over a 30-minute period
for 5 days, with coadministration of a single oral dose of warfarin (25 mg) on
the 5th day, had no significant effect on the pharmacokinetics of either drug
and did not significantly alter the INR (International Normalized Ratio).
Simvastatin
In 20 healthy adult subjects on
a stable daily dose of simvastatin 40 mg, administration of CUBICIN 4 mg/kg
q24h by IV infusion over a 30-minute period for 14 days (N=10) had no effect on
plasma trough concentrations of simvastatin and was not associated with a
higher incidence of adverse events, including skeletal myopathy, than in
subjects receiving placebo once daily (N=10) [see WARNINGS AND PRECAUTIONS
and DRUG INTERACTIONS].
Probenecid
Concomitant administration of
probenecid (500 mg 4 times daily) and a single dose of CUBICIN 4 mg/kg by IV
infusion over a 30-minute period in adults did not significantly alter the Cmax
or AUC0-∞ of daptomycin.
Microbiology
Daptomycin belongs to the
cyclic lipopeptide class of antibacterials. Daptomycin has clinical utility in
the treatment of infections caused by aerobic, Gram-positive bacteria. The in
vitro spectrum of activity of daptomycin encompasses most clinically relevant
Gram-positive pathogenic bacteria.
Daptomycin exhibits rapid,
concentration-dependent bactericidal activity against Gram-positive bacteria in
vitro. This has been demonstrated both by time-kill curves and by MBC/MIC
(minimum bactericidal concentration/minimum inhibitory concentration) ratios
using broth dilution methodology.
Daptomycin maintained bactericidal activity in vitro against
stationary phase S. aureus in simulated endocardial vegetations. The
clinical significance of this is not known.
Mechanism Of Action
Daptomycin binds to bacterial cell membranes and causes a
rapid depolarization of membrane potential. This loss of membrane potential
causes inhibition of DNA, RNA, and protein synthesis, which results in
bacterial cell death.
Resistance
The mechanism(s) of daptomycin resistance is not fully
understood. Currently, there are no known transferable elements that confer
resistance to daptomycin.
Interactions With Other Antibacterials
In vitro studies have investigated daptomycin
interactions with other antibacterials. Antagonism, as determined by kill curve
studies, has not been observed. In vitro synergistic interactions of daptomycin
with aminoglycosides, β-lactam antibacterials, and rifampin have been
shown against some isolates of staphylococci (including some
methicillin-resistant isolates) and enterococci (including some
vancomycinresistant isolates).
Complicated Skin And Skin Structure Infection (cSSSI)
Trials In Adults
The emergence of daptomycin non-susceptible isolates
occurred in 2 infected patients across the set of Phase 2 and pivotal Phase 3
clinical trials of cSSSI in adult patients. In one case, a non-susceptible S.
aureus was isolated from a patient in a Phase 2 trial who received CUBICIN
at less than the protocol-specified dose for the initial 5 days of therapy. In
the second case, a non-susceptible Enterococcus faecalis was isolated from a
patient with an infected chronic decubitus ulcer who was enrolled in a salvage
trial.
S. aureus Bacteremia/Endocarditis And Other
Post-Approval Trials In Adults
In subsequent clinical trials in adult patients,
non-susceptible isolates were recovered. S. aureus was isolated from a
patient in a compassionate-use trial and from 7 patients in the S. aureus
bacteremia/endocarditis trial [see Clinical Studies]. An E. faecium was
isolated from a patient in a vancomycin-resistant enterococci trial.
Antimicrobial Activity
Daptomycin has been shown to be active against most
isolates of the following microorganisms both in vitro and in clinical
infections [see INDICATIONS AND USAGE].
Gram-Positive Bacteria
Enterococcus faecalis (vancomycin-susceptible
isolates only)
Staphylococcus aureus (including
methicillin-resistant isolates)
Streptococcus agalactiae
Streptococcus dysgalactiae subsp. equisimilis
Streptococcus pyogenes
The following in vitro data are available, but their
clinical significance is unknown. At least 90 percent of the following bacteria
exhibit an in vitro minimum inhibitory concentration (MIC) less than or equal
to the susceptible breakpoint for daptomycin against isolates of genus or
organism group. However, the efficacy of daptomycin in treating clinical
infections due to these bacteria has not been established in adequate and
well-controlled clinical trials.
Gram-Positive Bacteria
Corynebacterium jeikeium
Enterococcus faecalis (vancomycin-resistant
isolates)
Enterococcus faecium (including
vancomycin-resistant isolates)
Staphylococcus epidermidis (including
methicillin-resistant isolates)
Staphylococcus haemolyticus
Susceptibility Test Methods
When available, the clinical microbiology laboratory
should provide the results of in vitro susceptibility test for antimicrobial
drugs 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 in the selection of an appropriate
antibacterial drug for treatment.
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
broth test method5,6 with the broth adjusted to a calcium content of
50 mg/L. The use of the agar dilution method is not recommended with daptomycin5.
The MICs should be interpreted according to criteria provided in Table 16.
Diffusion Techniques
Quantitative methods that require measurement of zone
diameters have not been shown to provide reproducible estimates of the
susceptibility of bacteria to daptomycin. The use of the disk diffusion method
is not recommended with daptomycin6,7.
Table 16: Susceptibility Interpretive Criteria for
Daptomycin
Pathogen |
Broth Dilution MIC* (mcg/mL) |
S |
I |
R |
Staphylococcus aureus (methicillin-susceptible and methicillin-resistant) |
≤1 |
(†) |
(†) |
Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus dysgalactiae subsp. equisimilis |
≤1 |
(†) |
(†) |
Enterococcus faecalis (vancomycin-susceptible only) |
≤4 |
(†) |
(†) |
Note: S, Susceptible; I,
Intermediate; R, Resistant.
*The MIC interpretive criteria for S. aureus and E. faecalis are
applicable only to tests performed by broth dilution using Mueller-Hinton broth
adjusted to a calcium content of 50 mg/L; the MIC interpretive criteria for Streptococcus
spp. other than S. pneumoniae are applicable only to tests performed by broth
dilution using Mueller-Hinton broth adjusted to a calcium content of 50 mg/L,
supplemented with 2 to 5% lysed horse blood, inoculated with a direct colony
suspension and incubated in ambient air at 35°C for 20 to 24 hours.
†The current absence of data on daptomycin-resistant isolates precludes
defining any categories other than “Susceptible.” Isolates yielding test
results suggestive of a “Non-Susceptible” category should be retested, and if
the result is confirmed, the isolate should be submitted to a reference
laboratory for further testing. |
A report of Susceptible (S)
indicates that the antimicrobial drug is likely to inhibit the growth of the
pathogen if the antimicrobial drug reaches the concentration usually achievable
at the site of infection.
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 individuals
performing the test5,6. Standard daptomycin powder should provide
the ranges of MIC values noted in Table 17.
Table 17: Acceptable Quality Control Ranges for
Daptomycin to Be Used in Validation of Susceptibility Test Results
Quality Control Strain |
Broth Dilution MIC Range* (mcg/mL) |
Enterococcus faecalis ATCC 29212 |
1-4 |
Staphylococcus aureus ATCC 29213 |
0.12-1 |
Streptococcus pneumoniae ATCC 49619† |
0.06-0.5 |
*The quality control ranges for S. aureus and E. faecalis are applicable only to tests performed by
broth dilution using Mueller-Hinton broth adjusted to a calcium content of 50
mg/L; the quality control range for Streptococcus pneumoniae is applicable only
to tests performed by broth dilution using Mueller-Hinton broth adjusted to a
calcium content of 50 mg/L, supplemented with 2 to 5% lysed horse blood,
inoculated with a direct colony suspension and incubated in ambient air at 35°C
for 20 to 24 hours.
†This strain may be used for validation of susceptibility test results when
testing Streptococcus spp. other than S. pneumoniae. |
Animal Toxicology And/Or Pharmacology
Adult Animals
In animals, daptomycin
administration has been associated with effects on skeletal muscle. However,
there were no changes in cardiac or smooth muscle. Skeletal muscle effects were
characterized by microscopic degenerative/regenerative changes and variable
elevations in creatine phosphokinase (CPK). No fibrosis or rhabdomyolysis was
evident in repeat-dose studies up to the highest doses tested in rats (150
mg/kg/day) and dogs (100 mg/kg/day). The degree of skeletal myopathy showed no
increase when treatment was extended from 1 month to up to 6 months. Severity
was dose-dependent.
All muscle effects, including microscopic changes, were
fully reversible within 30 days following the cessation of dosing.
In adult animals, effects on peripheral nerve (characterized
by axonal degeneration and frequently accompanied by significant losses of
patellar reflex, gag reflex, and pain perception) were observed at daptomycin
doses higher than those associated with skeletal myopathy. Deficits in the
dogs' patellar reflexes were seen within 2 weeks after the start of treatment
at 40 mg/kg/day (9 times the human Cmax at the 6 mg/kg/day dose), with some
clinical improvement noted within 2 weeks after the cessation of dosing.
However, at 75 mg/kg/day for 1 month, 7 of 8 dogs failed to regain full
patellar reflex responses within a 3-month recovery period. In a separate study
in dogs receiving doses of 75 and 100 mg/kg/day for 2 weeks, minimal residual
histological changes were noted at 6 months after the cessation of dosing. However,
recovery of peripheral nerve function was evident.
Tissue distribution studies in rats showed that
daptomycin is retained in the kidney but appears to penetrate the blood-brain
barrier only minimally following single and multiple doses.
Juvenile Animals
Target organs of daptomycin-related effects in 7-week-old
juvenile dogs were skeletal muscle and nerve, the same target organs as in
adult dogs. In juvenile dogs, nerve effects were noted at lower daptomycin
blood concentrations than in adult dogs following 28 days of dosing. In
contrast to adult dogs, juvenile dogs also showed evidence of effects in nerves
of the spinal cord as well as peripheral nerves after 28 days of dosing. No
nerve effects were noted in juvenile dogs following 14 days of dosing at doses
up to 75 mg/kg/day.
Administration of daptomycin to 7-week-old juvenile dogs
for 28 days at doses of 50 mg/kg/day produced minimal degenerative effects on
the peripheral nerve and spinal cord in several animals, with no corresponding clinical
signs. A dose of 150 mg/kg/day for 28 days produced minimal degeneration in the
peripheral nerve and spinal cord as well as minimal to mild degeneration of the
skeletal muscle in a majority of animals, accompanied by slight to severe
muscle weakness evident in most dogs. Following a 28-day recovery phase,
microscopic examination revealed recovery of the skeletal muscle and the ulnar
nerve effects, but nerve degeneration in the sciatic nerve and spinal cord was
still observed in all 150 mg/kg/day dogs.
Following once-daily administration of daptomycin to
juvenile dogs for 28 days, microscopic effects in nerve tissue were noted at a
Cmax value of 417 mcg/mL, which is approximately 3-fold less than the Cmax value
associated with nerve effects in adult dogs treated once daily with daptomycin
for 28 days (1308 mcg/mL).
Neonatal Animals
Neonatal dogs (4 to 31 days old) were more sensitive to
daptomycin-related adverse nervous system and/or muscular system effects than
either juvenile or adult dogs. In neonatal dogs, adverse nervous system and/or
muscular system effects were associated with a Cmax value approximately 3-fold
less than the Cmax in juvenile dogs, and 9-fold less than the Cmax in adult
dogs following 28 days of dosing. At a dose of 25 mg/kg/day with associated Cmax
and AUCinf values of 147 mcg/mL and 717 mcg•h/mL, respectively (1.6 and
1.0-fold the adult human Cmax and AUC, respectively, at the 6 mg/kg/day dose),
mild clinical signs of twitching and one incidence of muscle rigidity were
observed with no corresponding effect on body weight. These effects were found
to be reversible within 28 days after treatment had stopped.
At higher dose levels of 50 and 75 mg/kg/day with
associated Cmax and AUCinf values of ≥321 mcg/mL and ≥1470
mcg•h/mL, respectively, marked clinical signs of twitching, muscle rigidity in
the limbs, and impaired use of limbs were observed. Resulting decreases in body
weights and overall body condition at doses ≥50 mg/kg/day necessitated
early discontinuation by PND19.
Histopathological assessment did not reveal any
daptomycin-related changes in the peripheral and central nervous system tissue,
as well as in the skeletal muscle or other tissues assessed, at any dose level.
No adverse effects were observed in the dogs that
received daptomycin at 10 mg/kg/day, the NOAEL, with associated Cmax and AUCinf
values of 62 mcg/mL and 247 mcg•h/mL, respectively (or 0.6 and 0.4-fold the
adult human Cmax and AUC, respectively at the 6 mg/kg dose).
Clinical Studies
Complicated Skin And Skin Structure Infections
Adults With cSSSI
Adult patients with clinically documented complicated
skin and skin structure infections (cSSSI) (Table 18) were enrolled in two
randomized, multinational, multicenter, investigator-blinded trials comparing
CUBICIN (4 mg/kg IV q24h) with either vancomycin (1 g IV q12h) or an
anti-staphylococcal semi-synthetic penicillin (i.e., nafcillin, oxacillin,
cloxacillin, or flucloxacillin; 4 to 12 g IV per day). Patients could switch to
oral therapy after a minimum of 4 days of IV treatment if clinical improvement
was demonstrated. Patients known to have bacteremia at baseline were excluded.
Patients with creatinine clearance (CLCR) between 30 and 70 mL/min were to
receive a lower dose of CUBICIN as specified in the protocol; however, the
majority of patients in this subpopulation did not have the dose of CUBICIN
adjusted.
Table 18: Investigator's
Primary Diagnosis in the cSSSI Trials in Adult Patients (Population: ITT)
Primary Diagnosis |
Adult Patients (CUBICIN / Comparator*) |
Study 9801
N=264 / N=266 |
Study 9901
N=270 / N=292 |
Pooled
N=534 / N=558 |
Wound Infection |
99 (38%) / 116 (44%) |
102 (38%) / 108 (37%) |
201 (38%) / 224 (40%) |
Major Abscess |
55 (21%) / 43 (16%) |
59 (22%) / 65 (22%) |
114 (21%) / 108 (19%) |
Ulcer Infection |
71 (27%) / 75 (28%) |
53 (20%) / 68 (23%) |
124 (23%) / 143 (26%) |
Other Infection† |
39 (15%) / 32 (12%) |
56 (21%) / 51 (18%) |
95 (18%) / 83 (15%) |
*Comparator: vancomycin (1 g IV
q12h) or an anti-staphylococcal semi-synthetic penicillin (i.e., nafcillin,
oxacillin, cloxacillin, or flucloxacillin; 4 to 12 g/day IV in divided doses).
†The majority of cases were subsequently categorized as complicated cellulitis,
major abscesses, or traumatic wound infections. |
One trial was conducted
primarily in the United States and South Africa (study 9801), and the second
was conducted at non-US sites only (study 9901). The two trials were similar in
design but differed in patient characteristics, including history of diabetes
and peripheral vascular disease. There were a total of 534 adult patients
treated with CUBICIN and 558 treated with comparator in the two trials. The
majority (89.7%) of patients received IV medication exclusively.
The efficacy endpoints in both
trials were the clinical success rates in the intent-to-treat (ITT) population
and in the clinically evaluable (CE) population. In study 9801, clinical
success rates in the ITT population were 62.5% (165/264) in patients treated
with CUBICIN and 60.9% (162/266) in patients treated with comparator drugs.
Clinical success rates in the CE population were 76.0% (158/208) in patients
treated with CUBICIN and 76.7% (158/206) in patients treated with comparator
drugs. In study 9901, clinical success rates in the ITT population were 80.4%
(217/270) in patients treated with CUBICIN and 80.5% (235/292) in patients
treated with comparator drugs. Clinical success rates in the CE population were
89.9% (214/238) in patients treated with CUBICIN and 90.4% (226/250) in
patients treated with comparator drugs.
The success rates by pathogen
for microbiologically evaluable patients are presented in Table 19.
Table 19: Clinical Success
Rates by Infecting Pathogen in the cSSSI Trials in Adult Patients (Population:
Microbiologically Evaluable)
Pathogen |
Success Rate n/N (%) |
CUBICIN |
Comparator* |
Methicillin-susceptible Staphylococcus aureus (MSSA)† |
170/198 (86%) |
180/207 (87%) |
Methicillin-resistant Staphylococcus aureus (MRSA)† |
21/28 (75%) |
25/36 (69%) |
Streptococcus pyogenes |
79/84 (94%) |
80/88 (91%) |
Streptococcus agalactiae |
23/27 (85%) |
22/29 (76%) |
Streptococcus dysgalactiae subsp. equisimilis |
8/8 (100%) |
9/11 (82%) |
Enterococcus faecalis (vancomycin-susceptible only) |
27/37 (73%) |
40/53 (76%) |
*Comparator: vancomycin (1 g IV
q12h) or an anti-staphylococcal semi-synthetic penicillin (i.e., nafcillin,
oxacillin, cloxacillin, or flucloxacillin; 4 to 12 g/day IV in divided doses).
†As determined by the central laboratory. |
Pediatric Patients (1 to 17 Years of Age) With cSSSI
The cSSSI pediatric trial was a
single prospective multi-center, randomized, comparative trial. A total of 396
pediatric patients aged 1 to 17 years with cSSSI caused by Gram positive
pathogens were enrolled into the study. Patients known to have bacteremia, osteomyelitis,
endocarditis, and pneumonia at baseline were excluded. Patients were enrolled
in a stepwise approach into four age groups and given age-dependent doses of
CUBICIN once daily for up to 14 days. The different age groups and doses
evaluated were as follows: Adolescents (12 to 17 years) treated with 5 mg/kg of
CUBICIN (n=113), Children (7 to 11 years) treated with 7 mg/kg of CUBICIN
(n=113), Children (2 to 6 years) treated with 9 mg/kg of CUBICIN (n=125) and
Infants (1 to <2 years) treated with 10 mg/kg (n= 45).
Patients were randomized 2:1 to
receive CUBICIN or a standard of care (SOC) comparator, which included
intravenous therapy with either vancomycin, clindamycin, or an
anti-staphylococcal semi-synthetic penicillin (nafcillin, oxacillin, or cloxacillin).
Patients could switch to oral therapy after clinical improvement was
demonstrated (no minimum IV dosing was required).
The primary objective of this
study was to evaluate the safety of CUBICIN. The clinical outcome was
determined by resolution or improvement of symptoms at the End-of-Treatment
(EOT), 3 days after the last dose, and Test-of-Cure (TOC), 7-14 days after the
last dose. Investigator observed outcomes were verified in a blinded fashion.
Of the 396 subjects randomized in the study, 389 subjects were treated with
CUBICIN or comparator and included in the ITT population. Of these, 257
subjects were randomized to the CUBICIN group and 132 subjects were randomized
to the comparator group. Approximately 95% of subjects switched to oral therapy.
The mean day of switch was day 4, and ranged from day 1 to day 14. The clinical
success rates determined at 7 - 14 days after last dose of therapy (IV and oral)
(TOC visit) were 88% (227/257) for CUBICIN and 86% (114/132) for comparator.
S. aureus Bacteremia/Endocarditis
Adults With S. aureus Bacteremia/Endocarditis
The efficacy of CUBICIN in the
treatment of adult patients with S. aureus bacteremia was demonstrated
in a randomized, controlled, multinational, multicenter, open-label trial. In
this trial, adult patients with at least one positive blood culture for S.
aureus obtained within 2 calendar days prior to the first dose of study
drug and irrespective of source were enrolled and randomized to either CUBICIN
(6 mg/kg IV q24h) or standard of care [an anti-staphylococcal semi-synthetic
penicillin 2 g IV q4h (nafcillin, oxacillin, cloxacillin, or flucloxacillin) or
vancomycin 1 g IV q12h, each with initial gentamicin 1 mg/kg IV every 8 hours
for first 4 days]. Of the patients in the comparator group, 93% received
initial gentamicin for a median of 4 days, compared with 1 patient (<1%) in
the CUBICIN group. Patients with prosthetic heart valves, intravascular foreign
material that was not planned for removal within 4 days after the first dose of
study medication, severe neutropenia, known osteomyelitis, polymicrobial
bloodstream infections, creatinine clearance <30 mL/min, and pneumonia were
excluded.
Upon entry, patients were classified for likelihood of
endocarditis using the modified Duke criteria (Possible, Definite, or Not
Endocarditis). Echocardiography, including a transesophageal echocardiogram
(TEE), was performed within 5 days following study enrollment. The choice of
comparator agent was based on the oxacillin susceptibility of the S. aureus
isolate. The duration of study treatment was based on the investigator's
clinical diagnosis. Final diagnoses and outcome assessments at Test of Cure (6
weeks after the last treatment dose) were made by a treatment-blinded
Adjudication Committee, using protocol-specified clinical definitions and a
composite primary efficacy endpoint (clinical and microbiological success) at
the Test of Cure visit.
A total of 246 patients ≥18 years of age (124
CUBICIN, 122 comparator) with S. aureus bacteremia were randomized from
48 centers in the US and Europe. In the ITT population, 120 patients received
CUBICIN and 115 received comparator (62 received an anti-staphylococcal
semi-synthetic penicillin and 53 received vancomycin). Thirty-five patients
treated with an anti-staphylococcal semi-synthetic penicillin received
vancomycin initially for 1 to 3 days, pending final susceptibility results for
the S. aureus isolates. The median age among the 235 patients in the ITT
population was 53 years (range: 21 to 91 years); 30/120 (25%) in the CUBICIN
group and 37/115 (32%) in the comparator group were ≥65 years of age. Of
the 235 ITT patients, there were 141 (60%) males and 156 (66%) Caucasians
across the two treatment groups. In addition, 176 (75%) of the ITT population
had systemic inflammatory response syndrome (SIRS) at baseline and 85 (36%) had
surgical procedures within 30 days prior to onset of the S. aureus bacteremia.
Eighty-nine patients (38%) had bacteremia caused by methicillin-resistant S.
aureus (MRSA). Entry diagnosis was based on the modified Duke criteria and
comprised 37 (16%) Definite, 144 (61%) Possible, and 54 (23%) Not Endocarditis.
Of the 37 patients with an entry diagnosis of Definite Endocarditis, all (100%)
had a final diagnosis of infective endocarditis, and of the 144 patients with
an entry diagnosis of Possible Endocarditis, 15 (10%) had a final diagnosis of
infective endocarditis as assessed by the Adjudication Committee. Of the 54
patients with an entry diagnosis of Not Endocarditis, 1 (2%) had a final
diagnosis of infective endocarditis as assessed by the Adjudication Committee.
In the ITT population, there were 182 patients with bacteremia
and 53 patients with infective endocarditis as assessed by the Adjudication
Committee, including 35 with right-sided endocarditis and 18 with left-sided
endocarditis. The 182 patients with bacteremia comprised 121 with complicated S.
aureus bacteremia and 61 with uncomplicated S. aureus bacteremia.
Complicated bacteremia was defined as S. aureus isolated
from blood cultures obtained on at least 2 different calendar days, and/or
metastatic foci of infection (deep tissue involvement), and classification of
the patient as not having endocarditis according to the modified Duke criteria.
Uncomplicated bacteremia was defined as S. aureus isolated from blood
culture(s) obtained on a single calendar day, no metastatic foci of infection,
no infection of prosthetic material, and classification of the patient as not
having endocarditis according to the modified Duke criteria. The definition of
right-sided infective endocarditis (RIE) used in the clinical trial was
Definite or Possible Endocarditis according to the modified Duke criteria and
no echocardiographic evidence of predisposing pathology or active involvement
of either the mitral or aortic valve. Complicated RIE comprised patients who
were not intravenous drug users, had a positive blood culture for MRSA, serum
creatinine ≥2.5 mg/dL, or evidence of extrapulmonary sites of infection.
Patients who were intravenous drug users, had a positive blood culture for
methicillin-susceptible S. aureus (MSSA), had serum creatinine <2.5
mg/dL, and were without evidence of extrapulmonary sites of infection were
considered to have uncomplicated RIE.
The coprimary efficacy endpoints in the trial were the
Adjudication Committee success rates at the Test of Cure visit (6 weeks after
the last treatment dose) in the ITT and Per Protocol (PP) populations. The
overall Adjudication Committee success rates in the ITT population were 44.2%
(53/120) in patients treated with CUBICIN and 41.7% (48/115) in patients
treated with comparator (difference = 2.4% [95% CI -10.2, 15.1]). The
success rates in the PP population were 54.4% (43/79) in patients treated with
CUBICIN and 53.3% (32/60) in patients treated with comparator (difference =
1.1% [95% CI -15.6, 17.8]).
Adjudication Committee success rates are shown in Table
20.
Table 20: Adjudication
Committee Success Rates at Test of Cure in the S. aureus Bacteremia/Endocarditis
Trial in Adult Patients (Population: ITT)
Population |
Success Rate n/N (%) |
Difference: CUBICIN-Comparator (Confidence Interval) |
CUBICIN 6 mg/kg |
Comparator* |
Overall |
53/120 (44%) |
48/115 (42%) |
2.4% (-10.2, 15.1)† |
Baseline Pathogen |
Methicillin-susceptible S. aureus |
33/74 (45%) |
34/70 (49%) |
-4.0% (-22.6, 14.6)‡ |
Methicillin-resistant S. aureus |
20/45 (44%) |
14/44 (32%) |
12.6% (-10.2, 35.5)‡ |
Entry Diagnosis§ |
Definite or Possible Infective Endocarditis |
41/90 (46%) |
37/91 (41%) |
4.9% (-11.6, 21.4)‡ |
Not Infective Endocarditis |
12/30 (40%) |
11/24 (46%) |
-5.8% (-36.2, 24.5)‡ |
Final Diagnosis |
Uncomplicated Bacteremia |
18/32 (56%) |
16/29 (55%) |
1.1% (-31.7, 33.9)¶ |
Complicated Bacteremia |
26/60 (43%) |
23/61 (38%) |
5.6% (-17.3, 28.6)¶ |
Right-Sided Infective Endocarditis |
8/19 (42%) |
7/16 (44%) |
-1.6% (-44.9, 41.6)¶ |
Uncomplicated Right-Sided Infective Endocarditis |
3/6 (50%) |
1/4 (25%) |
25.0% (-51.6, 100.0)¶ |
Complicated Right-Sided Infective Endocarditis |
5/13 (39%) |
6/12 (50%) |
-11.5% (-62.4, 39.4)¶ |
Left-Sided Infective Endocarditis |
1/9 (11%) |
2/9 (22%) |
-11.1% (-55.9, 33.6)¶ |
*Comparator: vancomycin (1 g IV
q12h) or an anti-staphylococcal semi-synthetic penicillin (i.e., nafcillin,
oxacillin, cloxacillin, or flucloxacillin; 2 g IV q4h), each with initial
low-dose gentamicin.
†95% Confidence Interval
‡97.5% Confidence Interval (adjusted for multiplicity)
§According to the modified Duke criteria8
¶99% Confidence Interval (adjusted for multiplicity) |
Eighteen (18/120) patients in the CUBICIN arm and 19/116
patients in the comparator arm died during the trial. These comprise 3/28
CUBICIN-treated patients and 8/26 comparator-treated patients with
endocarditis, as well as 15/92 CUBICIN-treated patients and 11/90
comparator-treated patients with bacteremia. Among patients with persisting or
relapsing S. aureus infections, 8/19 CUBICIN-treated patients and 7/11
comparator-treated patients died.
Overall, there was no difference in time to clearance of S.
aureus bacteremia between CUBICIN and comparator. The median time to
clearance in patients with MSSA was 4 days and in patients with MRSA was 8
days.
Failure of treatment due to persisting or relapsing S.
aureus infections was assessed by the Adjudication Committee in 19/120
(16%) CUBICIN-treated patients (12 with MRSA and 7 with MSSA) and 11/115 (10%)
comparator-treated patients (9 with MRSA treated with vancomycin and 2 with
MSSA treated with an anti-staphylococcal semi-synthetic penicillin). Among all
failures, isolates from 6 CUBICIN-treated patients and 1 vancomycin-treated
patient developed increasing MICs (reduced susceptibility) by central
laboratory testing during or following therapy. Most patients who failed due to
persisting or relapsing S. aureus infection had deep-seated infection
and did not receive necessary surgical intervention [see WARNINGS AND PRECAUTIONS].
Pediatric Patients (1 To 17 Years Of Age) With S. aureus Bacteremia
The pediatric S. aureus bacteremia study was
designed as a prospective multi-center, randomized, comparative trial to treat
pediatric patients aged 1 to 17 years with bacteremia. Patients known to have
endocarditis or pneumonia at baseline were excluded. Patients were enrolled in
a stepwise approach into three age groups and given age-dependent doses of
CUBICIN once daily for up to 42 days. The different age groups and doses
evaluated were as follows: Adolescents (12 to 17 years, n=14 patients) treated
with CUBICIN dosed at 7 mg/kg once daily, Children (7 to 11 years, n=19
patients) treated with CUBICIN dosed at 9 mg/kg once daily and Children (2 to 6
years, n=22 patients) treated with CUBICIN dosed at 12 mg/kg once daily. No
patients 1 to <2 years of age were enrolled.
Patients were randomized 2:1 to receive CUBICIN or a
standard of care comparator, which included intravenous therapy with
vancomycin, semi-synthetic penicillin, first generation cephalosporin or
clindamycin. Patients could switch to oral therapy after clinical improvement
was demonstrated (no minimum IV dosing was required).
The primary objective of this study was to assess the
safety of CUBICIN. The clinical outcome was determined by resolution or
improvement of symptoms at test-of-cure (TOC) visit, 7 to 14 days after the
last dose, which was assessed by the site level Blinded Evaluator.
Of the 82 subjects randomized in the study, 81 subjects
were treated with CUBICIN or comparator and included in the safety population,
and 73 had a proven S. aureus bacteremia at Baseline. Of these, 51
subjects were randomized to the CUBICIN group and 22 subjects were randomized
to the comparator group. The mean duration of IV therapy was 12 days, with a
range of 1 to 44 days. Forty-eight subjects switched to oral therapy, and the
mean duration of oral therapy was 21 days. The clinical success rates
determined at 7 to 14 days after last dose of therapy (IV and oral) (TOC visit)
were 88% (45/51) for CUBICIN and 77% (17/22) for comparator.
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