CLINICAL PHARMACOLOGY
Mechanism of Action
Enoxaparin is a low molecular weight heparin which has
antithrombotic properties.
Pharmacodynamics
In humans, enoxaparin given at a dose of 1.5 mg/kg
subcutaneously (SC) is characterized by a higher ratio of anti-Factor Xa to
anti-Factor IIa activity (mean ± SD, 14.0 ± 3.1) (based on areas under
anti-Factor activity versus time curves) compared to the ratios observed for
heparin (mean±SD, 1.22 ± 0.13). Increases of up to 1.8 times the control values
were seen in the thrombin time (TT) and the activated partial thromboplastin
time (aPTT). Enoxaparin at a 1 mg/kg dose (100 mg/mL concentration),
administered SC every 12 hours to patients in a large clinical trial resulted
in aPTT values of 45 seconds or less in the majority of patients (n = 1607). A
30 mg IV bolus immediately followed by a 1 mg/kg SC administration resulted in
aPTT post-injection values of 50 seconds. The average aPTT prolongation value
on Day 1 was about 16% higher than on Day 4.
Pharmacokinetics
Absorption
Pharmacokinetic trials were conducted using the 100 mg/mL
formulation. Maximum anti-Factor Xa and anti-thrombin (anti-Factor IIa)
activities occur 3 to 5 hours after SC injection of enoxaparin. Mean peak
anti-Factor Xa activity was 0.16 IU/mL (1.58 mcg/mL) and 0.38 IU/mL (3.83
mcg/mL) after the 20 mg and the 40 mg clinically tested SC doses, respectively.
Mean (n = 46) peak anti-Factor Xa activity was 1.1 IU/mL at steady state in
patients with unstable angina receiving 1 mg/kg SC every 12 hours for 14 days.
Mean absolute bioavailability of enoxaparin, after 1.5 mg/kg given SC, based on
anti-Factor Xa activity is approximately 100% in healthy subjects.
A 30 mg IV bolus immediately followed by a 1 mg/kg SC
every 12 hours provided initial peak anti-Factor Xa levels of 1.16 IU/mL (n=16)
and average exposure corresponding to 84% of steady-state levels. Steady state
is achieved on the second day of treatment.
Enoxaparin pharmacokinetics appear to be linear over the
recommended dosage ranges [see DOSAGE AND ADMINISTRATION]. After
repeated subcutaneous administration of 40 mg once daily and 1.5 mg/kg
once-daily regimens in healthy volunteers, the steady state is reached on day 2
with an average exposure ratio about 15% higher than after a single dose.
Steady-state enoxaparin activity levels are well predicted by single-dose
pharmacokinetics. After repeated subcutaneous administration of the 1 mg/kg
twice daily regimen, the steady state is reached from day 4 with mean exposure
about 65% higher than after a single dose and mean peak and trough levels of
about 1.2 and 0.52 IU/mL, respectively. Based on enoxaparin sodium
pharmacokinetics, this difference in steady state is expected and within the therapeutic
range.
Although not studied clinically, the 150 mg/mL
concentration of enoxaparin sodium is projected to result in anticoagulant
activities similar to those of 100 mg/mL and 200 mg/mL concentrations at the
same enoxaparin dose. When a daily 1.5 mg/kg SC injection of enoxaparin sodium
was given to 25 healthy male and female subjects using a 100 mg/mL or a 200
mg/mL concentration the following pharmacokinetic profiles were obtained [see
Table 13].
Table 13 : Pharmacokinetic Parameters* After 5 Days of
1.5 mg/kg SC Once Daily Doses of Enoxaparin Sodium Using 100 mg/mL or 200 mg/mL
Concentrations
|
Concentration |
Anti-Xa |
Anti-IIa |
Heptest |
aPTT |
Amax (IU/mL or Δ sec) |
100 mg/mL |
1.37 (±0.23) |
0.23 (±0.05) |
105 (±17) |
19 (±5) |
200 mg/mL |
1.45 (±0.22) |
0.26 (±0.05) |
111 (±17) |
22 (±7) |
90% CI |
102-110% |
|
102-111% |
|
tmax** (h) |
100 mg/mL |
3 (2-6) |
4 (2-5) |
2.5 (2-4.5) |
3 (2-4.5) |
200 mg/mL |
3.5 (2-6) |
4.5 (2.5-6) |
3.3 (2-5) |
3 (2-5) |
AUC (ss) (h*IU/mL or h* Δ sec) |
100 mg/mL |
14.26 (±2.93) |
1.54 (±0.61) |
1321 (±219) |
|
200 mg/mL |
15.43 (±2.96) |
1.77 (±0.67) |
1401 (±227) |
|
90% CI |
105-112% |
|
103-109% |
|
*Means ± SD at Day 5 and 90%
Confidence Interval (CI) of the ratio
**Median (range) |
Distribution
The volume of distribution of
anti-Factor Xa activity is about 4.3 L.
Elimination
Following intravenous (IV)
dosing, the total body clearance of enoxaparin is 26 mL/min. After IV dosing of
enoxaparin labeled with the gamma-emitter, 99mTc, 40% of
radioactivity and 8 to 20% of anti-Factor Xa activity were recovered in urine
in 24 hours. Elimination half-life based on anti-Factor Xa activity was 4.5
hours after a single SC dose to about 7 hours after repeated dosing.
Significant anti-Factor Xa activity persists in plasma for about 12 hours
following a 40 mg SC once a day dose.
Following SC dosing, the apparent clearance (CL/F) of
enoxaparin is approximately 15 mL/min.
Metabolism
Enoxaparin sodium is primarily metabolized in the liver
by desulfation and/or depolymerization to lower molecular weight species with
much reduced biological potency. Renal clearance of active fragments represents
about 10% of the administered dose and total renal excretion of active and
non-active fragments 40% of the dose.
Special Populations
Gender: Apparent clearance and Amax derived from
anti-Factor Xa values following single SC dosing (40 mg and 60 mg) were
slightly higher in males than in females. The source of the gender difference
in these parameters has not been conclusively identified; however, body weight
may be a contributing factor.
Geriatric: Apparent clearance and Amax derived
from anti-Factor Xa values following single and multiple SC dosing in geriatric
subjects were close to those observed in young subjects. Following once a day
SC dosing of 40 mg enoxaparin, the Day 10 mean area under anti-Factor Xa
activity versus time curve (AUC) was approximately 15% greater than the mean
Day 1 AUC value [see DOSAGE AND ADMINISTRATION and Use in Specific
Populations].
Renal Impairment: A linear relationship between
anti-Factor Xa plasma clearance and creatinine clearance at steady state has
been observed, which indicates decreased clearance of enoxaparin sodium in
patients with reduced renal function. Anti-Factor Xa exposure represented by
AUC, at steady state, is marginally increased in mild (creatinine clearance
50–80 mL/min) and moderate (creatinine clearance 30-50 mL/min) renal impairment
after repeated subcutaneous 40 mg once-daily doses. In patients with severe
renal impairment (creatinine clearance < 30 mL/min), the AUC at steady state
is significantly increased on average by 65% after repeated subcutaneous 40 mg
once-daily doses [see DOSAGE AND ADMINISTRATION and Use in Specific
Populations].
Hemodialysis: In a single study, elimination rate
appeared similar but AUC was two-fold higher than control population, after a
single 0.25 or 0.5 mg/kg intravenous dose.
Hepatic Impairment: Studies with enoxaparin in
patients with hepatic impairment have not been conducted and the impact of
hepatic impairment on the exposure to enoxaparin is unknown [see Use in
Specific Populations].
Weight: After repeated subcutaneous 1.5 mg/kg once
daily dosing, mean AUC of anti-Factor Xa activity is marginally higher at
steady state in obese healthy volunteers (BMI 30-48 kg/m²) compared
to non-obese control subjects, while Amax is not increased.
When non-weight adjusted dosing was administered, it was found
after a single-subcutaneous 40 mg dose, that anti-Factor Xa exposure is 52%
higher in low-weight women ( < 45 kg) and 27% higher in low-weight men ( < 57
kg) when compared to normal weight control subjects [see Use in Specific
Populations].
Pharmacokinetic interaction: No pharmacokinetic
interaction was observed between enoxaparin and thrombolytics when administered
concomitantly.
Animal Toxicology and/or Pharmacology
A single SC dose of 46.4 mg/kg enoxaparin was lethal to
rats. The symptoms of acute toxicity were ataxia, decreased motility, dyspnea,
cyanosis, and coma.
Reproductive and Developmental Toxicology
Teratology studies have been conducted in pregnant rats
and rabbits at SC doses of enoxaparin up to 30 mg/kg/day corresponding to 211
mg/m²/day and 410 mg/m²/day in rats and rabbits
respectively. There was no evidence of teratogenic effects or fetotoxicity due
to enoxaparin.
Clinical Studies
Prophylaxis of Deep Vein Thrombosis Following Abdominal
Surgery in Patients at Risk for Thromboembolic Complications
Abdominal surgery patients at risk include those who are
over 40 years of age, obese, undergoing surgery under general anesthesia
lasting longer than 30 minutes or who have additional risk factors such as
malignancy or a history of deep vein thrombosis (DVT) or pulmonary embolism
(PE).
In a double-blind, parallel group study of patients
undergoing elective cancer surgery of the gastrointestinal, urological, or
gynecological tract, a total of 1116 patients were enrolled in the study, and
1115 patients were treated. Patients ranged in age from 32 to 97 years (mean
age 67 years) with 52.7% men and 47.3% women. Patients were 98% Caucasian, 1.1%
Black, 0.4% Asian and 0.4% others. Lovenox 40 mg SC, administered once a day,
beginning 2 hours prior to surgery and continuing for a maximum of 12 days
after surgery, was comparable to heparin 5000 U every 8 hours SC in reducing
the risk of DVT. The efficacy data are provided below [see Table 14].
Table 14 : Efficacy of Lovenox in the Prophylaxis of
Deep Vein Thrombosis Following Abdominal Surgery
Indication |
Dosing Regimen |
Lovenox 40 mg q.d. SC
n (%) |
Heparin 5000 U q8h SC
n (%) |
All Treated Abdominal Surgery Patients |
555 (100) |
560 (100) |
Treatment Failures |
Total VTE1 (%) |
56 (10.1)
(95% CI2: 8 to 13) |
63 (11.3)
(95% CI: 9 to 14) |
DVT Only (%) |
54 (9.7)
(95% CI: 7 to 12) |
61 (10.9)
(95% CI: 8 to 13) |
1 VTE = Venous thromboembolic events which included DVT, PE,
and death considered to be thromboembolic in origin
2 CI = Confidence Interval |
In a second double-blind,
parallel group study, Lovenox 40 mg SC once a day was compared to heparin 5000
U every 8 hours SC in patients undergoing colorectal surgery (one-third with
cancer). A total of 1347 patients were randomized in the study and all patients
were treated. Patients ranged in age from 18 to 92 years (mean age 50.1 years)
with 54.2% men and 45.8% women. Treatment was initiated approximately 2 hours
prior to surgery and continued for approximately 7 to 10 days after surgery.
The efficacy data are provided below [see Table 15].
Table 15 : Efficacy of
Lovenox in the Prophylaxis of Deep Vein Thrombosis Following Colorectal Surgery
Indication |
Dosing Regimen |
Lovenox 40 mg q.d. SC
n (%) |
Heparin 5000 U q8h SC
n (%) |
All Treated Colorectal Surgery Patients |
673 (100) |
674 (100) |
Treatment Failures |
Total VTE1 (%) |
48 (7.1)
(95% CI2: 5 to 9) |
45 (6.7)
(95% CI: 5 to 9) |
DVT Only (%) |
47 (7.0)
(95% CI: 5 to 9) |
44 (6.5)
(95% CI: 5 to 8) |
1 VTE = Venous thromboembolic events which
included DVT, PE, and death considered to be thromboembolic in origin
2 CI = Confidence Interval |
Prophylaxis of Deep Vein
Thrombosis Following Hip or Knee Replacement Surgery
Lovenox has been shown to
reduce the risk of post-operative deep vein thrombosis (DVT) following hip or
knee replacement surgery.
In a double-blind study,
Lovenox 30 mg every 12 hours SC was compared to placebo in patients with hip
replacement. A total of 100 patients were randomized in the study and all
patients were treated. Patients ranged in age from 41 to 84 years (mean age
67.1 years) with 45% men and 55% women. After hemostasis was established,
treatment was initiated 12 to 24 hours after surgery and was continued for 10
to 14 days after surgery. The efficacy data are provided below [see Table 16].
Table 16 : Efficacy of
Lovenox in the Prophylaxis of Deep Vein Thrombosis Following Hip Replacement
Surgery
Indication |
Dosing Regimen |
Lovenox 30 mg q12h SC
n (%) |
Placebo q12h SC
n (%) |
All Treated Hip Replacement Patients |
50 (100) |
50 (100) |
Treatment Failures |
Total DVT (%) |
5 (10)1 |
23 (46) |
Proximal DVT (%) |
1 (2)2 |
11 (22) |
1 p value versus placebo = 0.0002
2 p value versus placebo = 0.0134 |
A double-blind, multicenter
study compared three dosing regimens of Lovenox in patients with hip
replacement. A total of 572 patients were randomized in the study and 568
patients were treated. Patients ranged in age from 31 to 88 years (mean age
64.7 years) with 63% men and 37% women. Patients were 93% Caucasian, 6% Black,
< 1% Asian, and 1% others. Treatment was initiated within two days after
surgery and was continued for 7 to 11 days after surgery. The efficacy data are
provided below [see Table 17].
Table 17 : Efficacy of
Lovenox in the Prophylaxis of Deep Vein Thrombosis Following Hip Replacement
Surgery
Indication |
Dosing Regimen |
10 mg q.d. SC
n (%) |
30 mg q12h SC
n (%) |
40 mg q.d. SC
n (%) |
All Treated Hip Replacement Patients |
161 (100) |
208 (100) |
199 (100) |
Treatment Failures |
Total DVT (%) |
40 (25) |
22 (11)1 |
27 (14) |
Proximal DVT (%) |
17 (11) |
8 (4)2 |
9 (5) |
1 p value versus Lovenox 10 mg once a day = 0.0008
2 p value versus Lovenox 10 mg once a day = 0.0168 |
There was no significant
difference between the 30 mg every 12 hours and 40 mg once a day regimens. In a
double-blind study, Lovenox 30 mg every 12 hours SC was compared to placebo in
patients undergoing knee replacement surgery. A total of 132 patients were
randomized in the study and 131 patients were treated, of which 99 had total
knee replacement and 32 had either unicompartmental knee replacement or tibial
osteotomy. The 99 patients with total knee replacement ranged in age from 42 to
85 years (mean age 70.2 years) with 36.4% men and 63.6% women. After hemostasis
was established, treatment was initiated 12 to 24 hours after surgery and was
continued up to 15 days after surgery. The incidence of proximal and total DVT
after surgery was significantly lower for Lovenox compared to placebo. The
efficacy data are provided below [see Table 18].
Table 18 : Efficacy of
Lovenox in the Prophylaxis of Deep Vein Thrombosis Following Total Knee
Replacement Surgery
Indication |
Dosing Regimen |
Lovenox 30 mg q12h SC
n (%) |
Placebo q12h SC
n (%) |
All Treated Total Knee Replacement Patients |
47 (100) |
52 (100) |
Treatment Failures |
Total DVT (%) |
5 (11)1
(95% CI2: 1 to 21) |
32 (62)
(95% CI: 47 to 76) |
Proximal DVT (%) |
0 (0)3
(95% Upper CL4: 5) |
7 (13)
(95% CI: 3 to 24) |
1 p value versus placebo = 0.0001
2 CI = Confidence Interval
3 p value versus placebo = 0.013
4 CL = Confidence Limit |
Additionally, in an open-label,
parallel group, randomized clinical study, Lovenox 30 mg every 12 hours SC in
patients undergoing elective knee replacement surgery was compared to heparin
5000 U every 8 hours SC. A total of 453 patients were randomized in the study
and all were treated. Patients ranged in age from 38 to 90 years (mean age 68.5
years) with 43.7% men and 56.3% women. Patients were 92.5% Caucasian, 5.3%
Black, and 0.6% others. Treatment was initiated after surgery and continued up
to 14 days. The incidence of deep vein thrombosis was significantly lower for
Lovenox compared to heparin.
Extended Prophylaxis of Deep Vein Thrombosis Following
Hip Replacement Surgery: In a study of extended prophylaxis for patients
undergoing hip replacement surgery, patients were treated, while hospitalized,
with Lovenox 40 mg SC, initiated up to 12 hours prior to surgery for the
prophylaxis of post-operative DVT. At the end of the peri-operative period, all
patients underwent bilateral venography. In a double-blind design, those
patients with no venous thromboembolic disease were randomized to a
post-discharge regimen of either Lovenox 40 mg (n = 90) once a day SC or to
placebo (n = 89) for 3 weeks. A total of 179 patients were randomized in the
double-blind phase of the study and all patients were treated. Patients ranged
in age from 47 to 87 years (mean age 69.4 years) with 57% men and 43% women. In
this population of patients, the incidence of DVT during extended prophylaxis
was significantly lower for Lovenox compared to placebo. The efficacy data are
provided below [see Table 19].
Table 19 : Efficacy of Lovenox in the Extended
Prophylaxis of Deep Vein Thrombosis Following Hip Replacement Surgery
Indication (Post-Discharge) |
Post-Discharge Dosing Regimen |
Lovenox 40 mg q.d. SC
n (%) |
Placebo q.d. SC
n (%) |
All Treated Extended Prophylaxis Patients |
90 (100) |
89 (100) |
Treatment Failures |
Total DVT (%) |
6 (7)1
(95% CI2: 3 to 14) |
18 (20)
(95% CI: 12 to 30) |
Proximal DVT (%) |
5 (6)3
(95% CI: 2 to 13) |
7 (8)
(95% CI: 3 to 16) |
1 p value versus placebo = 0.008
2 CI= Confidence Interval
3 p value versus placebo = 0.537 |
In a second study, patients
undergoing hip replacement surgery were treated, while hospitalized, with
Lovenox 40 mg SC, initiated up to 12 hours prior to surgery. All patients were
examined for clinical signs and symptoms of venous thromboembolic (VTE)
disease. In a double-blind design, patients without clinical signs and symptoms
of VTE disease were randomized to a post-discharge regimen of either Lovenox 40
mg (n = 131) once a day SC or to placebo (n = 131) for 3 weeks. A total of 262
patients were randomized in the study double-blind phase and all patients were
treated. Patients ranged in age from 44 to 87 years (mean age 68.5 years) with
43.1% men and 56.9% women. Similar to the first study the incidence of DVT
during extended prophylaxis was significantly lower for Lovenox compared to
placebo, with a statistically significant difference in both total DVT (Lovenox
21 [16%] versus placebo 45 [34%]; p = 0.001) and proximal DVT (Lovenox 8 [6%]
versus placebo 28 [21%]; p = < 0.001).
Prophylaxis of Deep Vein Thrombosis in Medical Patients
with Severely Restricted Mobility During Acute Illness
In a double blind multicenter, parallel group study,
Lovenox 20 mg or 40 mg once a day SC was compared to placebo in the prophylaxis
of deep vein thrombosis (DVT) in medical patients with severely restricted
mobility during acute illness (defined as walking distance of < 10 meters for
≤ 3 days). This study included patients with heart failure (NYHA Class
III or IV); acute respiratory failure or complicated chronic respiratory
insufficiency (not requiring ventilatory support): acute infection (excluding
septic shock); or acute rheumatic disorder [acute lumbar or sciatic pain,
vertebral compression (due to osteoporosis or tumor), acute arthritic episodes
of the lower extremities]. A total of 1102 patients were enrolled in the study,
and 1073 patients were treated. Patients ranged in age from 40 to 97 years
(mean age 73 years) with equal proportions of men and women. Treatment
continued for a maximum of 14 days (median duration 7 days). When given at a
dose of 40 mg once a day SC, Lovenox significantly reduced the incidence of DVT
as compared to placebo. The efficacy data are provided below [see Table 20].
Table 20 : Efficacy of Lovenox in the Prophylaxis of
Deep Vein Thrombosis in Medical Patients with Severely Restricted Mobility
During Acute Illness
Indication |
Dosing Regimen |
Lovenox 20 mg q.d. SC
n (%) |
Lovenox 40 mg q.d. SC
n (%) |
Placebo
n (%) |
All Treated Medical Patients During Acute Illness |
351 (100) |
360 (100) |
362 (100) |
Treatment Failure1 |
Total VTE2 (%) |
43 (12.3) |
16 (4.4) |
43 (11.9) |
Total DVT (%) |
43 (12.3)
(95% CI3 8.8 to 15.7) |
16 (4.4)
(95% CI3 2.3 to 6.6) |
41 (11.3)
(95% CI3 8.1 to 14.6) |
Proximal DVT (%) |
13 (3.7) |
5 (1.4) |
14 (3.9) |
1 Treatment failures during therapy, between Days 1 and 14
2 VTE = Venous thromboembolic events which included DVT, PE, and
death considered to be thromboembolic in origin
3 CI = Confidence Interval |
At approximately 3 months
following enrollment, the incidence of venous thromboembolism remained
significantly lower in the Lovenox 40 mg treatment group versus the placebo
treatment group.
Treatment of Deep Vein
Thrombosis with or without Pulmonary Embolism
In a multicenter, parallel group
study, 900 patients with acute lower extremity deep vein thrombosis (DVT) with
or without pulmonary embolism (PE) were randomized to an inpatient (hospital)
treatment of either (i) Lovenox 1.5 mg/kg once a day SC, (ii) Lovenox 1 mg/kg
every 12 hours SC, or (iii) heparin IV bolus (5000 IU) followed by a
continuous infusion (administered to achieve an aPTT of 55 to 85 seconds). A
total of 900 patients were randomized in the study and all patients were
treated. Patients ranged in age from 18 to 92 years (mean age 60.7 years) with
54.7% men and 45.3% women. All patients also received warfarin sodium (dose
adjusted according to PT to achieve an International Normalization Ratio [INR]
of 2.0 to 3.0), commencing within 72 hours of initiation of Lovenox or standard
heparin therapy, and continuing for 90 days. Lovenox or standard heparin
therapy was administered for a minimum of 5 days and until the targeted
warfarin sodium INR was achieved. Both Lovenox regimens were equivalent to standard
heparin therapy in reducing the risk of recurrent venous thromboembolism (DVT
and/or PE). The efficacy data are provided below [see Table 21].
Table 21 : Efficacy of
Lovenox in Treatment of Deep Vein Thrombosis with or without Pulmonary Embolism
Indication |
Dosing Regimen1 |
Lovenox 1.5 mg/kg q.d. SC
n (%) |
Lovenox 1 mg/kg q12h SC
n (%) |
Heparin aPTT Adjusted IV Therapy
n (%) |
All Treated DVT Patients with or without PE |
298 (100) |
312 (100) |
290 (100) |
Patient Outcome |
Total VTE2 (%) |
13 (4.4)3 |
9 (2.9) 3 |
12 (4.1) |
DVT Only (%) |
11 (3.7) |
7 (2.2) |
8 (2.8) |
Proximal DVT (%) |
9 (3.0) |
6 (1.9) |
7 (2.4) |
PE (%) |
2 (0.7) |
2 (0.6) |
4 (1.4) |
1 All patients were also treated with warfarin sodium
commencing within 72 hours of Lovenox or standard heparin therapy.
2 VTE = venous thromboembolic event (DVT and/or PE)
3 The 95% Confidence Intervals for the treatment differences for
total VTE were:
Lovenox once a day versus heparin (-3.0 to 3.5)
Lovenox every 12 hours versus heparin (-4.2 to 1.7). |
Similarly, in a multicenter,
open-label, parallel group study, patients with acute proximal DVT were
randomized to Lovenox or heparin. Patients who could not receive outpatient
therapy were excluded from entering the study. Outpatient exclusion criteria
included the following: inability to receive outpatient heparin therapy because
of associated co-morbid conditions or potential for non-compliance and inability
to attend follow-up visits as an outpatient because of geographic
inaccessibility. Eligible patients could be treated in the hospital, but ONLY
Lovenox patients were permitted to go home on therapy (72%). A total of 501
patients were randomized in the study and all patients were treated. Patients
ranged in age from 19 to 96 years (mean age 57.8 years) with 60.5% men and
39.5% women. Patients were randomized to either Lovenox 1 mg/kg every 12 hours
SC or heparin IV bolus (5000 IU) followed by a continuous infusion administered
to achieve an aPTT of 60 to 85 seconds (in-patient treatment). All patients
also received warfarin sodium as described in the previous study. Lovenox or
standard heparin therapy was administered for a minimum of 5 days. Lovenox was
equivalent to standard heparin therapy in reducing the risk of recurrent venous
thromboembolism. The efficacy data are provided below [see Table 22].
Table 22 : Efficacy of Lovenox in Treatment of Deep
Vein Thrombosis
Indication |
Dosing Regimen1 |
Lovenox 1 mg/kg q12h SC
n (%) |
Heparin aPTT Adjusted IV Therapy
n (%) |
All Treated DVT Patients |
247 (100) |
254 (100) |
Patient Outcome |
Total VTE2 (%) |
13 (5.3) 3 |
17 (6.7) |
DVT Only (%) |
11 (4.5) |
14 (5.5) |
Proximal DVT (%) |
10 (4.0) |
12 (4.7) |
PE (%) |
2 (0.8) |
3 (1.2) |
1 All patients were also treated with warfarin sodium
commencing on the evening of the second day of Lovenox or standard heparin
therapy.
2 VTE = venous thromboembolic event (deep vein thrombosis [DVT]
and/or pulmonary embolism [PE]).
3 The 95% Confidence Intervals for the treatment difference for
total VTE was: Lovenox versus heparin (- 5.6 to 2.7). |
Prophylaxis of Ischemic
Complications in Unstable Angina and Non-Q-Wave Myocardial Infarction
In a multicenter, double-blind,
parallel group study, patients who recently experienced unstable angina or
non-Q-wave myocardial infarction were randomized to either Lovenox 1 mg/kg
every 12 hours SC or heparin IV bolus (5000 U) followed by a continuous
infusion (adjusted to achieve an aPTT of 55 to 85 seconds). A total of 3171
patients were enrolled in the study, and 3107 patients were treated. Patients
ranged in age from 25-94 years (median age 64 years), with 33.4% of patients
female and 66.6% male. Race was distributed as follows: 89.8% Caucasian, 4.8%
Black, 2.0% Asian, and 3.5% other. All patients were also treated with
aspirin 100 to 325 mg per day. Treatment was initiated within 24 hours of the
event and continued until clinical stabilization, revascularization procedures,
or hospital discharge, with a maximal duration of 8 days of therapy. The
combined incidence of the triple endpoint of death, myocardial infarction, or
recurrent angina was lower for Lovenox compared with heparin therapy at 14 days
after initiation of treatment. The lower incidence of the triple endpoint was
sustained up to 30 days after initiation of treatment. These results were
observed in an analysis of both all-randomized and all-treated patients. The
efficacy data are provided below [see Table 23].
Table 23 : Efficacy of Lovenox in the Prophylaxis of
Ischemic Complications in Unstable Angina and Non-Q-Wave Myocardial Infarction
(Combined Endpoint of Death, Myocardial Infarction, or Recurrent Angina)
Indication |
Dosing Regimen1 |
Reduction (%) |
p Value |
Lovenox 1mg/kg q12h SC n (%) |
Heparin aPTT Adjusted IV Therapy n (%) |
All Treated Unstable Angina and Non-Q-Wave MI Patients |
1578 (100) |
1529 (100) |
|
|
Timepoint2 |
48 Hours |
96 (6.1) |
112 (7.3) |
1.2 |
0.12 |
14 Days |
261 (16.5) |
303 (19.8) |
3.3 |
0.017 |
30 Days |
313 (19.8) |
358 (23.4) |
3.6 |
0.014 |
1 All patients were also treated with aspirin 100 to 325 mg
per day.
2 Evaluation timepoints are after initiation of treatment. Therapy
continued for up to 8 days (median duration of 2.6 days). |
The combined incidence of death
or myocardial infarction at all time points was lower for Lovenox compared to
standard heparin therapy, but did not achieve statistical significance. The
efficacy data are provided below [see Table 24].
Table 24 : Efficacy of
Lovenox in the Prophylaxis of Ischemic Complications in Unstable Angina and
Non-Q-Wave Myocardial Infarction (Combined Endpoint of Death or Myocardial
Infarction)
Indication |
Dosing Regimen1 |
Reduction (%) |
p Value |
Lovenox 1 mg/kg q12h SC n (%) |
Heparin aPTT Adjusted IV Therapy n (%) |
All Treated Unstable Angina and Non-Q-Wave MI Patients |
1578 (100) |
1529 (100) |
|
|
Timepoint2 |
48 Hours |
16 (1.0) |
20 (1.3) |
0.3 |
0.126 |
14 Days |
76 (4.8) |
93 (6.1) |
1.3 |
0.115 |
30 Days |
96 (6.1) |
118 (7.7) |
1.6 |
0.069 |
1 All patients were also treated with aspirin
100 to 325 mg per day.
2 Evaluation
timepoints are after initiation of treatment. Therapy continued for up to 8
days (median duration of 2.6 days). |
In a survey one year following
treatment, with information available for 92% of enrolled patients, the
combined incidence of death, myocardial infarction, or recurrent angina
remained lower for Lovenox versus heparin (32.0% vs 35.7%).
Urgent revascularization
procedures were performed less frequently in the Lovenox group as compared to
the heparin group, 6.3% compared to 8.2% at 30 days (p = 0.047).
Treatment of Acute ST-Segment
Elevation Myocardial Infarction
In a multicenter, double-blind,
double-dummy, parallel group study, patients with acute ST-segment elevation
myocardial infarction (STEMI) who were to be hospitalized within 6 hours of
onset and were eligible to receive fibrinolytic therapy were randomized in a
1:1 ratio to receive either Lovenox or unfractionated heparin.
Study medication was initiated
between 15 minutes before and 30 minutes after the initiation of fibrinolytic
therapy. Unfractionated heparin was administered beginning with an IV bolus of
60 U/kg (maximum 4000 U) and followed with an infusion of 12 U/kg per hour
(initial maximum 1000 U per hour) that was adjusted to maintain an aPTT of 1.5
to 2 times the control value. The IV infusion was to be given for at least 48
hours. The enoxaparin dosing strategy was adjusted according to the patient's
age and renal function. For patients younger than 75 years of age, enoxaparin
was given as a single 30 mg intravenous bolus plus a 1 mg/kg SC dose followed
by an SC injection of 1 mg/kg every 12 hours. For patients at least 75 years of
age, the IV bolus was not given and the SC dose was reduced to 0.75 mg/kg every
12 hours. For patients with severe renal insufficiency (estimated creatinine
clearance of less than 30 mL per minute), the dose was to be modified to 1
mg/kg every 24 hours. The SC injections of enoxaparin were given until hospital
discharge or for a maximum of eight days (whichever came first). The mean
treatment duration for enoxaparin was 6.6 days. The mean treatment duration of
unfractionated heparin was 54 hours.
When percutaneous coronary
intervention was performed during study medication period, patients received
antithrombotic support with blinded study drug. For patients on enoxaparin, the
PCI was to be performed on enoxaparin (no switch) using the regimen established
in previous studies, i.e. no additional dosing, if the last SC administration
was less than 8 hours before balloon inflation, IV bolus of 0.3 mg/kg
enoxaparin if the last SC administration was more than 8 hours before balloon
inflation.
All patients were treated with
aspirin for a minimum of 30 days. Eighty percent of patients received a
fibrin-specific agent (19% tenecteplase, 5% reteplase and 55% alteplase) and
20% received streptokinase.
Among 20,479 patients in the
ITT population, the mean age was 60 years, and 76% were male. Racial
distribution was: 87% Caucasian, 9.8% Asian, 0.2% Black, and 2.8% other.
Medical history included previous MI (13%), hypertension (44%), diabetes (15%)
and angiographic evidence of CAD (5%). Concomitant medication included
aspirin (95%), beta-blockers (86%), ACE inhibitors (78%), statins (70%) and
clopidogrel (27%). The MI at entry was anterior in 43%, non-anterior in 56%,
and both in 1%.
The primary efficacy end point was the composite of death
from any cause or myocardial re-infarction in the first 30 days after
randomization. Total follow-up was one year.
The rate of the primary efficacy end point (death or
myocardial re-infarction) was 9.9% in the enoxaparin group, and 12.0% in the
unfractionated heparin group, a 17% reduction in the relative risk,
(P=0.000003) [see Table 25].
Table 25 : Efficacy of
Lovenox in the Treatment of Acute ST-Segment Elevation Myocardial Infarction
Outcome at 48 hours |
Enoxaparin
(N=10,256)
n (%) |
UFH
(N=10,223)
n (%) |
Relative Risk (95% CI) |
P Value |
Death or Myocardial Re-infarction |
478 (4.7) |
531 (5.2) |
0.90
(0.80 to 1.01) |
0.08 |
Death |
383 (3.7) |
390 (3.8) |
0.98
(0.85 to 1.12) |
0.76 |
Myocardial Re-infarction |
102 (1.0) |
156 (1.5) |
0.65
(0.51 to 0.84) |
< 0.001 |
Urgent Revascularization |
74 (0.7) |
96 (0.9) |
0.77
(0.57 to 1.04) |
0.09 |
Death or Myocardial Re-infarction or Urgent Revascularization |
548 (5.3) |
622 (6.1) |
0.88
(0.79 to 0.98) |
0.02 |
Outcome at 8 Days |
Death or Myocardial Re-infarction |
740 (7.2) |
954 (9.3) |
0.77
(0.71 to 0.85) |
< 0.001 |
Death |
559 (5.5) |
605 (5.9) |
0.92
(0.82 to 1.03) |
0.15 |
Myocardial Re-infarction |
204 (2.0) |
379 (3.7) |
0.54
(0.45 to 0.63) |
< 0.001 |
Urgent Revascularization |
145 (1.4) |
247 (2.4) |
0.59
(0.48 to 0.72) |
< 0.001 |
Death or Myocardial Re-infarction or Urgent Revascularization |
874 (8.5) |
1181 (11.6) |
0.74
(0.68 to 0.80) |
< 0.001 |
Outcome at 30 Days |
Primary efficacy endpoint (Death or Myocardial Re-infarction) |
1017 (9.9) |
1223 (12.0) |
0.83 (0.77 to 0.90) |
0.000003 |
Death |
708 (6.9) |
765 (7.5) |
0.92
(0.84 to 1.02) |
0.11 |
Myocardial Re-infarction |
352 (3.4) |
508 (5.0) |
0.69
(0.60 to 0.79) |
< 0.001 |
Urgent Revascularization |
213 (2.1) |
286 (2.8) |
0.74
(0.62 to 0.88) |
< 0.001 |
Death or Myocardial Re-infarction or Urgent Revascularization |
1199 (11.7) |
1479 (14.5) |
0.81
(0.75 to 0.87) |
< 0.001 |
Note: Urgent revascularization denotes episodes of
recurrent myocardial ischemia (without infarction) leading to the clinical
decision to perform coronary revascularization during the same hospitalization.
CI denotes confidence intervals.
The beneficial effect of
enoxaparin on the primary end point was consistent across key subgroups
including age, gender, infarct location, history of diabetes, history of prior
myocardial infarction, fibrinolytic agent administered, and time to treatment
with study drug (see Figure 1); however, it is necessary to interpret such
subgroup analyses with caution.
Figure 1: Relative Risks of
and Absolute Event Rates for the Primary End Point at 30 Days in Various
Subgroups *
* The primary efficacy end
point was the composite of death from any cause or myocardial re-infarction in
the first 30 days. The overall treatment effect of enoxaparin as compared to
the unfractionated heparin is shown at the bottom of the figure. For each
subgroup, the circle is proportional to the number and represents the point
estimate of the treatment effect and the horizontal lines represent the 95
percent confidence intervals. Fibrin-specific fibrinolytic agents included
alteplase, tenecteplase and reteplase. Time to treatment indicates the time
from the onset of symptoms to the administration of study drug (median, 3.2
hours).
The beneficial effect of
enoxaparin on the primary end point observed during the first 30 days was
maintained over a 12 month follow-up period (see Figure 2).
Figure 2 : Kaplan-Meier plot - death or myocardial
re-infarction at 30 days - ITT population
There is a trend in favor of
enoxaparin during the first 48 hours, but most of the treatment difference is
attributed to a step increase in the event rate in the UFH group at 48 hours
(seen in Figure 2), an effect that is more striking when comparing the event
rates just prior to and just subsequent to actual times of discontinuation.
These results provide evidence that UFH was effective and that it would be
better if used longer than 48 hours. There is a similar increase in endpoint
event rate when enoxaparin was discontinued, suggesting that it too was
discontinued too soon in this study.
The rates of major hemorrhages
(defined as requiring 5 or more units of blood for transfusion, or 15% drop in
hematocrit or clinically overt bleeding, including intracranial hemorrhage) at
30 days were 2.1% in the enoxaparin group and 1.4% in the unfractionated
heparin group. The rates of intracranial hemorrhage at 30 days were 0.8%
in the enoxaparin group 0.7% in the unfractionated heparin group. The 30-day
rate of the composite endpoint of death, myocardial re-infarction or ICH (a
measure of net clinical benefit) was significantly lower in the enoxaparin
group (10.1%) as compared to the heparin group (12.2%).