CLINICAL PHARMACOLOGY
Mechanism Of Action
The precise mechanism(s) by which levetiracetam exerts its
antiepileptic effect is unknown. The antiepileptic activity of levetiracetam
was assessed in a number of animal models of epileptic seizures. Levetiracetam
did not inhibit single seizures induced by maximal stimulation with electrical
current or different chemoconvulsants and showed only minimal activity in
submaximal stimulation and in threshold tests. Protection was observed,
however, against secondarily generalized activity from focal seizures induced
by pilocarpine and kainic acid, two chemoconvulsants that induce seizures that
mimic some features of human complex partial seizures with secondary
generalization. Levetiracetam also displayed inhibitory properties in the
kindling model in rats, another model of human complex partial seizures, both
during kindling development and in the fully kindled state. The predictive
value of these animal models for specific types of human epilepsy is uncertain.
In vitro and in vivo recordings of epileptiform activity
from the hippocampus have shown that levetiracetam inhibits burst firing
without affecting normal neuronal excitability, suggesting that levetiracetam
may selectively prevent hypersynchronization of epileptiform burst firing and
propagation of seizure activity.
Levetiracetam at concentrations of up to 10 μM did not
demonstrate binding affinity for a variety of known receptors, such as those
associated with benzodiazepines, GABA (gamma-aminobutyric acid), glycine, NMDA
(N-methyl-D-aspartate), re-uptake sites, and second messenger systems.
Furthermore, in vitro studies have failed to find an effect of levetiracetam on
neuronal voltage-gated sodium or Ttype calcium currents and levetiracetam does
not appear to directly facilitate GABAergic neurotransmission. However, in
vitro studies have demonstrated that levetiracetam opposes the activity of
negative modulators of GABA- and glycine-gated currents and partially inhibits
N-type calcium currents in neuronal cells.
A saturable and stereoselective neuronal binding site in rat
brain tissue has been described for levetiracetam. Experimental data indicate
that this binding site is the synaptic vesicle protein SV2A, thought to be
involved in the regulation of vesicle exocytosis. Although the molecular
significance of levetiracetam binding to synaptic vesicle protein SV2A is not
understood, levetiracetam and related analogs showed a rank order of affinity
for SV2A which correlated with the potency of their antiseizure activity in
audiogenic seizure-prone mice. These findings suggest that the interaction of levetiracetam
with the SV2A protein may contribute to the antiepileptic mechanism of action
of the drug.
Pharmacodynamics
Effects On QTc Interval
The effect of KEPPRA on QTc prolongation was evaluated in a
randomized, double-blind, positivecontrolled (moxifloxacin 400 mg) and
placebo-controlled crossover study of KEPPRA (1000 mg or 5000 mg) in 52 healthy
subjects. The upper bound of the 90% confidence interval for the largest placebo-adjusted,
baseline-corrected QTc was below 10 milliseconds. Therefore, there was no evidence
of significant QTc prolongation in this study.
Pharmacokinetics
Equivalent doses of intravenous (IV) levetiracetam and oral
levetiracetam result in equivalent Cmax, Cmin, and total systemic exposure to
levetiracetam when the IV levetiracetam is administered as a 15- minute
infusion.
The pharmacokinetics of levetiracetam have been studied in
healthy adult subjects, adults and pediatric patients with epilepsy, elderly
subjects, and subjects with renal and hepatic impairment.
Overview
Levetiracetam is rapidly and almost completely absorbed
after oral administration. Levetiracetam injection and tablets are
bioequivalent. The pharmacokinetics of levetiracetam are linear and
timeinvariant, with low intra- and inter-subject variability. Levetiracetam is
not significantly protein-bound ( < 10% bound) and its volume of distribution
is close to the volume of intracellular and extracellular water. Sixty-six
percent (66%) of the dose is renally excreted unchanged. The major metabolic
pathway of levetiracetam (24% of dose) is an enzymatic hydrolysis of the
acetamide group. It is not liver cytochrome P450 dependent. The metabolites
have no known pharmacological activity and are renally excreted. Plasma
half-life of levetiracetam across studies is approximately 6-8 hours. It is
increased in the elderly (primarily due to impaired renal clearance) and in
subjects with renal impairment.
Distribution
The equivalence of levetiracetam injection and the oral
formulation was demonstrated in a bioavailability study of 17 healthy volunteers.
In this study, levetiracetam 1500 mg was diluted in 100 mL 0.9% sterile saline
solution and was infused over 15 minutes. The selected infusion rate provided plasma
concentrations of levetiracetam at the end of the infusion period similar to
those achieved at Tmax after an equivalent oral dose. It is demonstrated that
levetiracetam 1500 mg intravenous infusion is equivalent to levetiracetam 3 Ã
500 mg oral tablets. The time independent pharmacokinetic profile of levetiracetam
was demonstrated following 1500 mg intravenous infusion for 4 days with BID
dosing. The AUC(0-12) at steady-state was equivalent to AUCinf following an
equivalent single dose.
Levetiracetam and its major metabolite are less than 10%
bound to plasma proteins; clinically significant interactions with other drugs
through competition for protein binding sites are therefore unlikely.
Metabolism
Levetiracetam is not extensively metabolized in humans. The
major metabolic pathway is the enzymatic hydrolysis of the acetamide group,
which produces the carboxylic acid metabolite, ucb L057 (24% of dose) and is
not dependent on any liver cytochrome P450 isoenzymes. The major metabolite is
inactive in animal seizure models. Two minor metabolites were identified as the
product of hydroxylation of the 2-oxo-pyrrolidine ring (2% of dose) and opening
of the 2-oxo-pyrrolidine ring in position 5 (1% of dose). There is no
enantiomeric interconversion of levetiracetam or its major metabolite.
Elimination
Levetiracetam plasma half-life in adults is 7 ± 1 hour and
is unaffected by either dose, route of administration or repeated
administration. Levetiracetam is eliminated from the systemic circulation by renal
excretion as unchanged drug which represents 66% of administered dose. The
total body clearance is 0.96 mL/min/kg and the renal clearance is 0.6
mL/min/kg. The mechanism of excretion is glomerular filtration with subsequent
partial tubular reabsorption. The metabolite ucb L057 is excreted by glomerular
filtration and active tubular secretion with a renal clearance of 4 mL/min/kg. Levetiracetam
elimination is correlated to creatinine clearance. Levetiracetam clearance is
reduced in patients with renal impairment [see DOSAGE AND ADMINISTRATION
and Use in Specific Populations].
Specific Populations
Elderly
Pharmacokinetics of levetiracetam were evaluated in 16
elderly subjects (age 61-88 years) with creatinine clearance ranging from 30 to
74 mL/min. Following oral administration of twice-daily dosing for 10 days,
total body clearance decreased by 38% and the half-life was 2.5 hours longer in
the elderly compared to healthy adults. This is most likely due to the decrease
in renal function in these subjects.
Pediatric Patients
- Intravenous Formulation
A population pharmacokinetic analysis for the intravenous formulation
was conducted in 49 pediatric patients (1 month to < 16 years of age)
weighing 3-79 kg. Patients received levetiracetam as a 15-minute IV infusion at
doses between 14 mg/kg/day and 60 mg/kg/day twice daily. Plasma concentrations
and model derived steady-state exposure AUC (0-12) were within the range of the
exposure observed in pediatric patients receiving equivalent doses of the oral
solution.
- Oral Formulations
Pharmacokinetics of levetiracetam were evaluated in 24 pediatric patients
(age 6-12 years) after single oral dose (20 mg/kg) of the immediate release
formulation of KEPPRA. The body weight adjusted apparent clearance of
levetiracetam was approximately 40% higher than in adults.
A repeat dose pharmacokinetic study was conducted in pediatric patients (age
4-12 years) at doses of 20 mg/kg/day, 40 mg/kg/day, and 60 mg/kg/day of the
immediate release formulation of KEPPRA. The evaluation of the pharmacokinetic
profile of levetiracetam and its metabolite (ucb L057) in 14 pediatric patients
demonstrated rapid absorption of levetiracetam at all doses, with a Tmax of
about 1 hour and a t½ of 5 hours across all dosing levels. The
pharmacokinetics of levetiracetam in pediatric patients was linear between 20
to 60 mg/kg/day. The potential interaction of levetiracetam with other AEDs was
also evaluated in these patients. Levetiracetam had no significant effect on
the plasma concentrations of carbamazepine, valproic acid, topiramate or
lamotrigine. However, there was about a 22% increase of apparent clearance of
levetiracetam when it was co-administered with an enzyme-inducing AED (e.g.,
carbamazepine).
Following single dose administration (20 mg/kg) of a 10% oral solution to
pediatric patients with epilepsy (1 month to < 4 years), levetiracetam was
rapidly absorbed and peak plasma concentrations were observed approximately 1
hour after dosing. Levetiracetam half-life in pediatric patients 1 month to
< 4 years with epilepsy was shorter (5.3 h) than in adults (7.2 h), and
apparent clearance (1.5 mL/min/kg) was faster than in adults (0.96 mL/min/kg).
Population pharmacokinetic analysis showed that body weight was significantly
correlated to the clearance of levetiracetam in pediatric patients; clearance
increased with an increase in body weight.
Pregnancy
Levetiracetam levels may decrease during pregnancy.
Gender
Levetiracetam Cmax and AUC were 20% higher in women (N=11) compared
to men (N=12). However, clearances adjusted for body weight were comparable.
Race
Formal pharmacokinetic studies of the effects of race have
not been conducted. Cross-study comparisons involving Caucasians (N=12) and
Asians (N=12), however, show that pharmacokinetics of levetiracetam were
comparable between the two races. Because levetiracetam is primarily renally excreted
and there are no important racial differences in creatinine clearance,
pharmacokinetic differences due to race are not expected.
Renal Impairment
The disposition of levetiracetam was studied in adult
subjects with varying degrees of renal function. Total body clearance of
levetiracetam is reduced in patients with impaired renal function by 40% in the
mild group (CLcr = 50-80 mL/min), 50% in the moderate group (CLcr = 30-50
mL/min) and 60% in the severe renal impairment group (CLcr < 30 mL/min).
Clearance of levetiracetam is correlated with creatinine clearance.
In anuric (end stage renal disease) patients, the total body
clearance decreased 70% compared to normal subjects (CLcr > 80mL/min).
Approximately 50% of the pool of levetiracetam in the body is removed during a
standard 4 hour hemodialysis procedure [see DOSAGE AND ADMINISTRATION].
Hepatic Impairment
In subjects with mild (Child-Pugh A) to moderate (Child-Pugh
B) hepatic impairment, the pharmacokinetics of levetiracetam were unchanged. In
patients with severe hepatic impairment (Child- Pugh C), total body clearance
was 50% that of normal subjects, but decreased renal clearance accounted for
most of the decrease. No dose adjustment is needed for patients with hepatic
impairment.
Drug Interactions
In vitro data on metabolic interactions indicate that
levetiracetam is unlikely to produce, or be subject to, pharmacokinetic
interactions. Levetiracetam and its major metabolite, at concentrations well
above Cmax levels achieved within the therapeutic dose range, are neither
inhibitors of, nor high affinity substrates for, human liver cytochrome P450
isoforms, epoxide hydrolase or UDP-glucuronidation enzymes. In addition,
levetiracetam does not affect the in vitro glucuronidation of valproic acid.
Potential pharmacokinetic interactions of or with
levetiracetam were assessed in clinical pharmacokinetic studies (phenytoin,
valproate, warfarin, digoxin, oral contraceptive, probenecid) and through
pharmacokinetic screening in the placebo-controlled clinical studies in
epilepsy patients.
Phenytoin
KEPPRA (3000 mg daily) had no effect on the pharmacokinetic
disposition of phenytoin in patients with refractory epilepsy. Pharmacokinetics
of levetiracetam were also not affected by phenytoin.
Valproate
KEPPRA (1500 mg twice daily) did not alter the
pharmacokinetics of valproate in healthy volunteers. Valproate 500 mg twice
daily did not modify the rate or extent of levetiracetam absorption or its
plasma clearance or urinary excretion. There also was no effect on exposure to
and the excretion of the primary metabolite, ucb L057.
Other Antiepileptic Drugs
Potential drug interactions between KEPPRA and other AEDs
(carbamazepine, gabapentin, lamotrigine, phenobarbital, phenytoin, primidone
and valproate) were also assessed by evaluating the serum concentrations of
levetiracetam and these AEDs during placebo-controlled clinical studies. These
data indicate that levetiracetam does not influence the plasma concentration of
other AEDs and that these AEDs do not influence the pharmacokinetics of levetiracetam.
Effect of AEDs in Pediatric Patients
There was about a 22% increase of apparent total body
clearance of levetiracetam when it was coadministered with enzyme-inducing
AEDs. Dose adjustment is not recommended. Levetiracetam had no effect on plasma
concentrations of carbamazepine, valproate, topiramate, or lamotrigine.
Oral Contraceptives
KEPPRA (500 mg twice daily) did not influence the
pharmacokinetics of an oral contraceptive containing 0.03 mg ethinyl estradiol
and 0.15 mg levonorgestrel, or of the luteinizing hormone and progesterone
levels, indicating that impairment of contraceptive efficacy is unlikely.
Coadministration of this oral contraceptive did not influence the
pharmacokinetics of levetiracetam.
Digoxin
KEPPRA (1000 mg twice daily) did not influence the
pharmacokinetics and pharmacodynamics (ECG) of digoxin given as a 0.25 mg dose
every day. Coadministration of digoxin did not influence the pharmacokinetics
of levetiracetam.
Warfarin
KEPPRA (1000 mg twice daily) did not influence the
pharmacokinetics of R and S warfarin. Prothrombin time was not affected by
levetiracetam. Coadministration of warfarin did not affect the pharmacokinetics
of levetiracetam.
Probenecid
Probenecid, a renal tubular secretion blocking agent,
administered at a dose of 500 mg four times a day, did not change the
pharmacokinetics of levetiracetam 1000 mg twice daily. Cssmax of the
metabolite, ucb L057, was approximately doubled in the presence of probenecid
while the fraction of drug excreted unchanged in the urine remained the same.
Renal clearance of ucb L057 in the presence of probenecid decreased 60%,
probably related to competitive inhibition of tubular secretion of ucb L057.
The effect of KEPPRA on probenecid was not studied.
Clinical Studies
All clinical studies supporting the efficacy of KEPPRA utilized
oral formulations. The finding of efficacy of KEPPRA injection is based on the
results of studies using an oral formulation of KEPPRA, and on the
demonstration of comparable bioavailability of the oral and parenteral
formulations [see Pharmacokinetics].
Partial Onset Seizures
Effectiveness In Partial Onset Seizures In Adults With Epilepsy
The effectiveness of KEPPRA as adjunctive therapy (added to
other antiepileptic drugs) in adults was established in three multicenter,
randomized, double-blind, placebo-controlled clinical studies in patients who
had refractory partial onset seizures with or without secondary generalization.
The tablet formulation was used in all these studies. In these studies, 904
patients were randomized to placebo, 1000 mg, 2000 mg, or 3000 mg/day. Patients
enrolled in Study 1 or Study 2 had refractory partial onset seizures for at
least two years and had taken two or more classical AEDs. Patients enrolled in
Study 3 had refractory partial onset seizures for at least 1 year and had taken
one classical AED. At the time of the study, patients were taking a stable dose
regimen of at least one and could take a maximum of two AEDs. During the
baseline period, patients had to have experienced at least two partial onset
seizures during each 4-week period.
Study 1
Study 1 was a double-blind, placebo-controlled,
parallel-group study conducted at 41 sites in the United States comparing
KEPPRA 1000 mg/day (N=97), KEPPRA 3000 mg/day (N=101), and placebo (N=95) given
in equally divided doses twice daily. After a prospective baseline period of 12
weeks, patients were randomized to one of the three treatment groups described
above. The 18-week treatment period consisted of a 6-week titration period,
followed by a 12-week fixed dose evaluation period, during which concomitant
AED regimens were held constant. The primary measure of effectiveness was a between
group comparison of the percent reduction in weekly partial seizure frequency
relative to placebo over the entire randomized treatment period (titration +
evaluation period). Secondary outcome variables included the responder rate
(incidence of patients with ≥ 50% reduction from baseline in partial onset
seizure frequency). The results of the analysis of Study 1 are displayed in
Table 10.
Table 10: Reduction in Mean Over Placebo in Weekly
Frequency of Partial Onset Seizures in Study 1
|
Placebo
(N=95) |
KEPPRA 1000 mg/day
(N=97) |
KEPPRA 3000 mg/day
(N=101) |
Percent reduction in partial seizure frequency over placebo |
- |
26.1%* |
30.1%* |
*statistically significant versus placebo |
The percentage of patients (y-axis) who achieved ≥ 50%
reduction in weekly seizure rates from baseline in partial onset seizure
frequency over the entire randomized treatment period (titration +Â evaluation
period) within the three treatment groups (x-axis) is presented in Figure 1.
Figure 1: Responder Rate ( ≥ 50% Reduction from
Baseline) in Study 1
*statistically significant versus placebo
Study 2
Study 2 was a double-blind, placebo-controlled, crossover
study conducted at 62 centers in Europe comparing KEPPRA 1000 mg/day (N=106),
KEPPRA 2000 mg/day (N=105), and placebo (N=111) given in equally divided doses
twice daily.
The first period of the study (Period A) was designed to be
analyzed as a parallel-group study. After a prospective baseline period of up
to 12 weeks, patients were randomized to one of the three treatment groups
described above. The 16-week treatment period consisted of the 4-week titration
period followed by a 12-week fixed dose evaluation period, during which
concomitant AED regimens were held constant. The primary measure of
effectiveness was a between group comparison of the percent reduction in weekly
partial seizure frequency relative to placebo over the entire randomized
treatment period (titration + evaluation period). Secondary outcome variables
included the responder rate (incidence of patients with ≥ 50% reduction
from baseline in partial onset seizure frequency). The results of the analysis
of Period A are displayed in Table 11.
Table 11: Reduction in Mean Over Placebo in Weekly
Frequency of Partial Onset Seizures in Study 2: Period A
|
Placebo
(N=111) |
KEPPRA 1000 mg/day
(N=106) |
KEPPRA 2000 mg/day
(N=105) |
Percent reduction in partial seizure frequency over placebo |
- |
17.1%* |
21.4%* |
*statistically significant versus placebo |
The percentage of patients (y-axis) who achieved ≥ 50%
reduction in weekly seizure rates from baseline in partial onset seizure
frequency over the entire randomized treatment period (titration + evaluation
period) within the three treatment groups (x-axis) is presented in Figure 2.
Figure 2: Responder Rate ( ≥ 50% Reduction from
Baseline) in Study 2: Period A
*statistically significant versus placebo
The comparison of KEPPRA 2000 mg/day to KEPPRA 1000 mg/day
for responder rate was statistically significant (P=0.02). Analysis of the
trial as a cross-over yielded similar results.
Study 3
Study 3 was a double-blind, placebo-controlled,
parallel-group study conducted at 47 centers in Europe comparing KEPPRA 3000
mg/day (N=180) and placebo (N=104) in patients with refractory partial onset seizures,
with or without secondary generalization, receiving only one concomitant AED.
Study drug was given in two divided doses. After a prospective baseline period
of 12 weeks, patients were randomized to one of two treatment groups described
above. The 16-week treatment period consisted of a 4-week titration period,
followed by a 12-week fixed dose evaluation period, during which concomitant
AED doses were held constant. The primary measure of effectiveness was a
between group comparison of the percent reduction in weekly seizure frequency
relative to placebo over the entire randomized treatment period (titration +
evaluation period). Secondary outcome variables included the responder rate
(incidence of patients with ≥ 50% reduction from baseline in partial onset
seizure frequency). Table 12 displays the results of the analysis of Study 3.
Table 12: Reduction in Mean Over Placebo in Weekly
Frequency of Partial Onset Seizures in Study 3
|
Placebo
(N=104) |
KEPPRA 3000 mg/day
(N=180) |
Percent reduction in partial seizure frequency over placebo |
- |
23.0%* |
*statistically significant versus placebo |
The percentage of patients (y-axis) who achieved ≥ 50%
reduction in weekly seizure rates from baseline in partial onset seizure
frequency over the entire randomized treatment period (titration + evaluation
period) within the two treatment groups (x-axis) is presented in Figure 3.
Figure 3: Responder Rate ( ≥ 50% Reduction from
Baseline) in Study 3
*statistically significant versus placebo
Effectiveness In Partial Onset Seizures In Pediatric
Patients 4 Years To 16 Years With Epilepsy
Study 4 was a multicenter, randomized double-blind,
placebo-controlled study, in pediatric patients 4 to 16 years of age with
partial seizures uncontrolled by standard antiepileptic drugs (AEDs). Study 4
was conducted at 60 sites in North America. The study consisted of an 8-week
baseline period and 4-week titration period followed by a 10-week evaluation
period. Eligible patients who still experienced, on a stable dose of 1-2 AEDs,
at least 4 partial onset seizures during the 4 weeks prior to screening, as
well as at least 4 partial onset seizures in each of the two 4-week baseline
periods, were randomized to receive either KEPPRA or placebo. Dosing was
initiated at a dose of 20 mg/kg/day in two divided doses. During the treatment
period, KEPPRA doses were adjusted in 20 mg/kg/day increments, at 2- week
intervals to the target dose of 60 mg/kg/day. The primary measure of efficacy
was a between group comparison of the percent reduction in weekly partial
seizure frequency relative to placebo over the entire 14-week randomized
treatment period (titration + evaluation period). Secondary outcome variables
included the responder rate (incidence of patients with ≥ 50% reduction
from baseline in partial onset seizure frequency per week). The enrolled population
included 198 patients (KEPPRA N=101, placebo N=97) with refractory partial
onset seizures, whether or not secondarily generalized. Table 13 displays the
results of Study 4.
Table 13: Reduction in Mean Over Placebo in Weekly
Frequency of Partial Onset Seizures in Study 4
|
Placebo
(N=97) |
KEPPRA
(N=101) |
Percent reduction in partial seizure frequency over placebo |
- |
26.8%* |
*statistically significant versus placebo |
The percentage of patients (y-axis) who achieved ≥ 50%
reduction in weekly seizure rates from baseline in partial onset seizure
frequency over the entire randomized treatment period (titration + evaluation
period) within the two treatment groups (x-axis) is presented in Figure 4.
Figure 4: Responder Rate ( ≥ 50% Reduction from
Baseline) in Study 4
*statistically significant versus placebo
Effectiveness In Partial Onset Seizures In Pediatric
Patients 1 Month To < 4 Years With Epilepsy
Study 5 was a multicenter, randomized double-blind,
placebo-controlled study, in pediatric patients 1 month to less than 4 years of
age with partial seizures, uncontrolled by standard epileptic drugs (AEDs). Study
5 was conducted at 62 sites in North America, South America, and Europe. Study 5 consisted of a 5-day evaluation period, which included a 1-day titration
period followed by a 4-day maintenance period. Eligible patients who
experienced, on a stable dose of 1-2 AEDs, at least 2 partial onset seizures
during the 48-hour baseline video EEG were randomized to receive either KEPPRA
or placebo. Randomization was stratified by age range as follows: 1 month to
less than 6 months of age (N=4 treated with KEPPRA), 6 months to less than 1
year of age (N=8 treated with KEPPRA), 1 year to less than 2 years of age (N=20
treated with KEPPRA), and 2 years to less than 4 years of age (N=28 treated
with KEPPRA). KEPPRA dosing was determined by age and weight as follows:
children 1 month to less than 6 months old were randomized to a target dose of
40 mg/kg/day, and children 6 months to less than 4 years old were randomized to
a target dose of 50 mg/kg/day. The primary measure of efficacy was the
responder rate (percent of patients with ≥ 50% reduction from baseline in
average daily partial onset seizure frequency) assessed by a blinded central
reader using a 48-hour video EEG performed during the last two days of the
4-day maintenance period. The enrolled population included 116 patients (KEPPRA
N=60, placebo N=56) with refractory partial onset seizures, whether or not secondarily
generalized. A total of 109 patients were included in the efficacy analysis. A
statistically significant difference between KEPPRA and placebo was observed in
Study 5 (see Figure 5). The treatment effect associated with KEPPRA was
consistent across age groups.
Figure 5: Responder Rate for All Patients Ages 1 Month to
< 4 Years ( ≥ 50% Reduction from Baseline) in Study 5
*statistically significant versus placebo
Myoclonic Seizures In Patients With Juvenile Myoclonic
Epilepsy
Study 6 was a multicenter, randomized, double-blind,
placebo-controlled study in patients 12 years of age and older with juvenile
myoclonic epilepsy (JME) experiencing myoclonic seizures. Study 6 was conducted
at 37 sites in 14 countries. Eligible patients on a stable dose of 1
antiepileptic drug (AED) experiencing one or more myoclonic seizures per day
for at least 8 days during the prospective 8-week baseline period were
randomized to either KEPPRA or placebo (KEPPRA N=60, placebo N=60). Patients
were titrated over 4 weeks to a target dose of 3000 mg/day and treated at a
stable dose of 3000 mg/day over 12 weeks (evaluation period). Study drug was
given in 2 divided doses. The primary measure of efficacy was the proportion of
patients with at least 50% reduction in the number of days per week with one or
more myoclonic seizures during the treatment period (titration + evaluation periods)
as compared to baseline. Table 14 displays the results for the 113 patients
with JME in this study. Of 120 patients enrolled, 113 had a diagnosis of
confirmed or suspected JME. The results of Study 6 are displayed in Table 14.
Table 14: Responder Rate ( ≥ 50% Reduction from
Baseline) in Myoclonic Seizure Days per Week in Study 6
|
Placebo
(N=59) |
KEPPRA
(N=54) |
Percentage of responders |
23.7% |
60.4%* |
*statistically significant versus placebo |
Primary Generalized Tonic-Clonic Seizures
Effectiveness In Primary Generalized Tonic-Clonic Seizures In
Patients ≥ 6 Years Of Age
Study 7 was a multicenter, randomized, double-blind,
placebo-controlled study in patients 6 years of age and older with idiopathic
generalized epilepsy experiencing primary generalized tonic-clonic (PGTC) seizures.
Study 7 was conducted at 50 sites in 8 countries. Eligible patients on a stable
dose of 1 or 2 antiepileptic drugs (AEDs) experiencing at least 3 PGTC seizures
during the 8-week combined baseline period (at least one PGTC seizure during
the 4 weeks prior to the prospective baseline period and at least one PGTC
seizure during the 4-week prospective baseline period) were randomized to
either KEPPRA or placebo. The 8-week combined baseline period is referred to as
“baseline” in the remainder of this section. Patients were titrated
over 4 weeks to a target dose of 3000 mg/day for adults or a pediatric target
dose of 60 mg/kg/day and treated at a stable dose of 3000 mg/day (or 60
mg/kg/day for children) over 20 weeks (evaluation period). Study drug was given
in 2 equally divided doses per day. The primary measure of efficacy was the
percent reduction from baseline in weekly PGTC seizure frequency for KEPPRA and
placebo treatment groups over the treatment period (titration + evaluation periods).
The population included 164 patients (KEPPRA N=80, placebo N=84) with
idiopathic generalized epilepsy (predominately juvenile myoclonic epilepsy,
juvenile absence epilepsy, childhood absence epilepsy, or epilepsy with Grand Mal
seizures on awakening) experiencing primary generalized tonic-clonic seizures.
Each of these syndromes of idiopathic generalized epilepsy was well represented
in this patient population.
There was a statistically significant decrease from baseline
in PGTC frequency in the KEPPRA-treated patients compared to the
placebo-treated patients in Study 7 (see Table 15).
Table 15: Median Percent Reduction from Baseline in PGTC
Seizure Frequency per Week in Study 7
|
Placebo
(N=84) |
KEPPRA
(N=78) |
Percentage reduction in PGTC seizure frequency |
44.6% |
77.6%* |
*statistically significant versus placebo |
The percentage of patients (y-axis) who achieved ≥ 50%
reduction in weekly seizure rates from baseline in PGTC seizure frequency over
the entire randomized treatment period (titration + evaluation period) within
the two treatment groups (x-axis) is presented in Figure 6.
Figure 6: Responder Rate ( ≥ 50% Reduction from
Baseline) in PGTC Seizure Frequency per Week in Study 7
*statistically significant versus placebo