Effect of Age and Comedication on Levetiracetam Pharmacokinetics and Tolerability

Levetiracetam in brain ischemia: clinical implications in neuroprotection and prevention of post-stroke epilepsy

Several new antiepileptic drugs (AEDs) have been introduced for clinical use recently. These new AEDs, like the classic AEDs, target multiple cellular sites both pre- and postsynaptically. The use of AEDs as a possible neuroprotective strategy in brain ischemia is receiving increasing attention and the antiepileptic drug levetiracetam, a 2S-(2-oxo-1-pyrrolidiny1) butanamide, belonging to the pyrrolidone family, could have a crucial role in regulation of epileptogenesis and neuroprotection. Recent observations suggest that levetiracetam is both safe and effective against post-stroke seizures. In this review, the potential neuroprotective role in brain ischemia and the therapeutic implications of levetiracetam in post-stroke epilepsy are discussed.

Efficacy and tolerability of levetiracetam in children with epilepsy

OBJECTIVE

To assess the efficacy and tolerability of levetiracetam (Lev) in children with epilepsy.

METHODS

Open-label observational, prospective, single arm, non-interventional study examining patients (≤14 years) with epilepsy, receiving mono- or combination therapy with levetiracetam. Levetiracetam was started at a dose of approximately 10mg/kg/day. The dose was titrated up with 10mg/kg increments if seizures were poorly controlled but the maximum daily dose could not be more than 60 mg/kg/day. Documented were seizure type and frequency, levetiracetam dose and side effects.

RESULTS

120 patients (39.3% females, mean age 4.5 ± 3.9 years) were enrolled. Average duration of follow-up was 10.3 ± 3.5 months. At study endpoint, 64.8% of patients got seizure free and 83.0% got a seizure reduction of ≥50%. Observed side effects were somnolence, dysphoria, nervousness, dystrophy, somnipathy, asitia, debilitation, etc. and the incidence rate in the study was 47.5%. Four (3.3%) of 120 patients withdrew because of intolerance of side effects. The estimated one year retention rate of levetiracetam was 73.3%. Poor effect was the most common reason for withdrawal.

CONCLUSIONS

In our study, it seemed that levetiracetam was safe and effective for a wide range of epileptic seizures in children with epilepsy.

Levetiracetam Extended Release as Adjuvant Therapy for the Control of Partial-onset Seizures

Extended release (XR) formulation of levetiracetam (LEV) is approved by the Food and Drug Administration as an add-on to other antiepileptic drugs (AEDs) for adults with partial onset seizures. This is based on class-I evidence demonstrating significant seizure reduction in once daily dosing. Keppra-XR is marketed with the brand name of Keppra XR since 2008 (UCB Pharma). Its original immediate release (IR) formulation has been in the market since 2000. LEV has a unique molecular structure which is chemically unrelated to existing AEDs. The precise mechanism of action is unknown. Animal studies showed binding to synaptic vesicle protein SV2A, thought to be involved in modulating synaptic neurotransmitter release. LEV-IR is proven effective as adjunctive therapy for partial-onset seizures, primary generalized tonic-clonic seizures and myoclonic seizures. It was shown to be equivalent to carbamazepine as first-line treatment for partial-onset seizures. The extended release formulation added advantages such as better tolerance and increased compliance.

Age and comedications influence levetiracetam pharmacokinetics in children

The pharmacokinetics of many antiepileptic drugs differs between adults and children. The influence of age and concomitant medications on the dose/concentration ratio of levetiracetam was examined in 103 children with epilepsy. Dosing and plasma levels of levetiracetam and concomitant antiepileptic drugs were reviewed retrospectively. The dose/concentration ratio was calculated as the weight-normalized dose (mg/kg/day) divided by the steady-state trough plasma drug level, which was used as a measure of apparent oral clearance of levetiracetam. Children were classified into age groups and treatment groups: levetiracetam given with enzyme inducers (n = 24) or nonenzyme inducers (n = 69), or as monotherapy (n = 10). Levetiracetam clearance differed significantly between age groups (0-4, 5-11, and 12-17 years), i.e., the younger the child, the higher the clearance. The increase was 1.7-fold between the youngest and oldest age groups. Children on enzyme inducers exhibited significantly higher clearance (1.3-fold), compared with those on nonenzyme inducers and monotherapy. Levetiracetam did not influence the clearance of lamotrigine, valproate, topiramate, or clonazepam. In conclusion, younger age and comedication with an enzyme inducer increased levetiracetam clearance. This finding should be taken into account when treating individual patients.

Levetiracetam enhances p53-mediated MGMT inhibition and sensitizes glioblastoma cells to temozolomide

Antiepileptic drugs (AEDs) are frequently used to treat seizures in glioma patients. AEDs may have an unrecognized impact in modulating O(6)-methylguanine-DNA methyltransferase (MGMT), a DNA repair protein that has an important role in tumor cell resistance to alkylating agents. We report that levetiracetam (LEV) is the most potent MGMT inhibitor among several AEDs with diverse MGMT regulatory actions. In vitro, when used at concentrations within the human therapeutic range for seizure prophylaxis, LEV decreases MGMT protein and mRNA expression levels. Chromatin immunoprecipitation analysis reveals that LEV enhances p53 binding on the MGMT promoter by recruiting the mSin3A/histone deacetylase 1 (HDAC1) corepressor complex. However, LEV does not exert any MGMT inhibitory activity when the expression of either p53, mSin3A, or HDAC1 is abrogated. LEV inhibits malignant glioma cell proliferation and increases glioma cell sensitivity to the monofunctional alkylating agent temozolomide. In 4 newly diagnosed patients who had 2 craniotomies 7-14 days apart, prior to the initiation of any tumor-specific treatment, samples obtained before and after LEV treatment showed the inhibition of MGMT expression. Our results suggest that the choice of AED in patients with malignant gliomas may have an unrecognized impact in clinical practice and research trial design.

Measuring outcomes of treatment with antiepileptic drugs in clinical trials

Epilepsy often requires life-long treatment with antiepileptic drugs (AEDs). For clinicians to meet the challenges of patient management, data on AED performance based on clearly defined and consistently applied outcome measures are needed. Ideally, the design of AED clinical trials should be relevant to real-world settings, providing reliable, valid, and comprehensive information on efficacy, tolerability, and quality of life (QOL). Several types of outcome parameters have been employed: percent seizure reduction, responder rate based on > or =50% seizure reduction, seizure-free rate, time to first seizure, time to Nth seizure, adverse events, QOL, retention, and compliance. Each provides important information about a drug's performance. Here we define and review endpoints for measuring AED treatment success and explore the concepts of efficacy, tolerability, QOL, retention, and compliance as well as their usefulness as clinical trial endpoints.

Thrombocytopenia during levetiracetam therapy

A 64-year-old patient with symptomatic epilepsy developed thrombocytopenia during treatment with levetiracetam (LEV). As no other medical reason could be evaluated, a medication side effect was postulated. The only new drugs were valproic acid (since 3 weeks) and levetiracetam (since 3 days). After valproic acid medication was ended, thrombocytopenia did not improve and even worsened further. Finally levetiracetam administration was ended and trombocytopenia resolved rapidly and completely within few days.

Impending status epilepticus and anxiety in a pregnant woman treated with levetiracetam

Levetiracetam (LEV) has been considered to undergo no significant change in bioavailability during pregnancy; however, it was recently demonstrated to display modifications leading to a drop in its serum level. We describe a patient who displayed impending status epilepticus following a fall in her LEV level during the first trimester. The oral LEV dosage was increased, and phenytoin and benzodiazepines were transiently prescribed. She experienced severe anxiety and an unbearable fear over the deleterious consequences for her baby despite repeated, reassuring explanations. Her anxiety was so strong that she aborted electively shortly after leaving the hospital. This observation emphasizes the need for LEV level monitoring during pregnancy to prevent unexpected seizure relapses. The rapid increase in levetiracetam dosage in parallel with the loss of seizure control is suspected of facilitating the induction of significant psychiatric changes.

Levetiracetam in newly diagnosed late-onset post-stroke seizures: a prospective observational study

Levetiracetam (LEV) monotherapy was investigated in 35 patients (pts) (16M/19F, 71.9+/-7.3 years of age) with late-onset post-stroke seizures (i.e. seizures occurring at least 2 weeks after an ischemic stroke) in a prospective open-label study. Overall, 27 pts (77.1%) achieved a condition of seizure freedom (defined as 1 year without seizures): 19 (54.3%) at a daily LEV dose of 1000mg, 7 (20.0%) at 1500mg, 1 (2.8%) at 2000mg. Four pts (11.4%) discontinued the drug because of intolerable side effects (drowsiness associated to gait disturbance in 1 pt, and aggressive behaviour in the remaining 3 pts); 3 pts were unresponsive at a dose of 3000mg, and 1 pt was lost at follow-up. These observations suggest that LEV exhibits safety and efficacy profiles which make it an optimal candidate as a first-choice drug against post-stroke seizures.

Antiepileptic drugs--best practice guidelines for therapeutic drug monitoring: a position paper by the subcommission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies

Although no randomized studies have demonstrated a positive impact of therapeutic drug monitoring (TDM) on clinical outcome in epilepsy, evidence from nonrandomized studies and everyday clinical experience does indicate that measuring serum concentrations of old and new generation antiepileptic drugs (AEDs) can have a valuable role in guiding patient management provided that concentrations are measured with a clear indication and are interpreted critically, taking into account the whole clinical context. Situations in which AED measurements are most likely to be of benefit include (1) when a person has attained the desired clinical outcome, to establish an individual therapeutic concentration which can be used at subsequent times to assess potential causes for a change in drug response; (2) as an aid in the diagnosis of clinical toxicity; (3) to assess compliance, particularly in patients with uncontrolled seizures or breakthrough seizures; (4) to guide dosage adjustment in situations associated with increased pharmacokinetic variability (e.g., children, the elderly, patients with associated diseases, drug formulation changes); (5) when a potentially important pharmacokinetic change is anticipated (e.g., in pregnancy, or when an interacting drug is added or removed); (6) to guide dose adjustments for AEDs with dose-dependent pharmacokinetics, particularly phenytoin.

Value of therapeutic drug monitoring in epilepsy

Therapeutic drug monitoring (TDM) of antiepileptic drugs (AEDs) has made it possible to study the individual variations in drug utilization, to reveal noncompliance in patients and for quality assurance aspects. Even if there is a shortage of data from randomized controlled studies concerning the effectiveness of using TDM as an aid to dosage adjustment, experience from nonrandomized investigations and long-lasting clinical experience have shown that TDM of both older and newer AEDs may be of clinical benefit if used appropriately. The main situations for TDM include: after starting treatment to provide a baseline steady-state concentration for further evaluation of an individual therapeutic concentration; after change in drug dosage, in particular when nonlinear kinetics apply; at therapeutic failure to sort out a pharmacokinetic explanation for uncontrolled seizures or side effects; in case of drug interactions; and when pharmacokinetic changes due to physiological or pathological changes are foreseen (e.g., age-dependent conditions [children, elderly], pregnancy, hepatic disease, renal disease or gastrointestinal conditions potentially affecting drug absorption) and change in drug formulation (brand name/generic). Recently, new terminology and definitions have been suggested by the International League Against Epilepsy. The reference range is a range of drug concentrations quoted by laboratories and is not a therapeutic range. Emphasis should be placed on the concept of an individual therapeutic concentration.

Levetiracetam in the treatment of epilepsy

Epilepsy is a common chronic disorder that requires long-term antiepileptic drug therapy. Approximately one half of patients fail the initial antiepileptic drug and about 35% are refractory to medical therapy, highlighting the continued need for more effective and better tolerated drugs. Levetiracetam is an antiepileptic drug marketed since 2000. Its novel mechanism of action is modulation of synaptic neurotransmitter release through binding to the synaptic vesicle protein SV2A in the brain. Its pharmacokinetic advantages include rapid and almost complete absorption, minimal insignificant binding to plasma protein, absence of enzyme induction, absence of interactions with other drugs, and partial metabolism outside the liver. The availability of an intravenous preparation is yet another advantage. It has been demonstrated effective as adjunctive therapy for refractory partial-onset seizures, primary generalized tonic-clonic seizures, and myoclonic seizures of juvenile myoclonic epilepsy. In addition, it was found equivalent to controlled release carbamazepine as first-line therapy for partial-onset seizures, both in efficacy and tolerability. Its main adverse effects in randomized adjunctive trials in adults have been somnolence, asthenia, infection, and dizziness. In children, the behavioral adverse effects of hostility and nervousness were also noted. Levetiracetam is an important addition to the treatment of epilepsy.

Serum concentration/dose ratio of levetiracetam before, during and after pregnancy

PURPOSE

To investigate changes in levetiracetam (LEV) serum concentration/dose ratio (C/D-ratio) in relation to pregnancy.

METHODS

Altogether 21 consecutive pregnancies in 20 women with epilepsy receiving LEV during gestation were studied retrospectively. The main target variable was the C/D-ratio before and during pregnancy, and in the post partum period. Secondary target variables were changes in LEV dose, concomitant use of other antiepileptic drugs and seizure frequency. Student's paired t-test and two-sample t-test for independent samples were used to test for statistically significant changes in C/D-ratio means.

RESULTS

Mean C/D-ratio in the third trimester was 50% of the mean C/D-ratio at baseline (p<0.001, n=11). Baseline levels were reached within the first weeks after pregnancy. The interindividual variability was pronounced.

CONCLUSIONS

Serum concentrations of LEV declined significantly in the third trimester of pregnancy and increased rapidly after delivery.