Topiramate in add-on therapy: results from an open-label, observational study

Effectiveness of dose-escalated topiramate monotherapy and add-on therapy in neurosurgery-related epilepsy: A prospective study

BACKGROUND

Lesional and symptomatic causes of epilepsy are the most common neurological disorders of the brain. Topiramate effectively controls newly diagnosed epilepsy and refractory focal seizures, but high-dose topiramate does not improve seizure control. This study aimed to evaluate the clinical efficacy and safety of dose-escalated topiramate as first-line monotherapy and add-on therapy in patients with neurosurgery-related epilepsy.

MATERIAL AND METHODS

A total of 55 neurosurgical patients with epilepsy were divided into monotherapy and add-on therapy groups and both groups received topiramate via the dose-escalation method. The primary efficacy outcomes were seizure-free rate and seizure response rate. Adverse events and seizure frequency were recorded.

RESULTS

The seizure response rate in the first month of monotherapy was significantly better than that of add-on therapy (89% vs 65%, P < .05), but no significant differences were found in seizure response rates between the 2 groups after 2 months of treatment. Both monotherapy and add-on therapy were effective in controlling seizures, with mean seizure frequency of 0.725 vs 0.536 and seizure-free rate of 88% vs 78.6%. Both treatments showed good improvement of seizure frequency in patients without tumor. The efficacy of monotherapy was better than that of add-on therapy (80% vs 29.2%) in patients with body mass index (BMI) ≤24. However, add-on therapy was better than monotherapy (76.7% vs 21.4%) in patients with BMI > 24. Dizziness (25.5%) and headache (16.4%) were the most common adverse events. No severe adverse event such as cognitive impairment was observed.

CONCLUSIONS

Dose-escalated topiramate monotherapy and add-on therapy demonstrate good efficacy and safety, with fewer adverse events in seizure control in neurosurgical patients.

Antiepileptic Drug Selection According to Seizure Type in Adult Patients with Epilepsy

Epilepsy is a common neurological disorder that is mainly treated using antiepileptic drugs. Several antiepileptic drugs such as phenobarbital, phenytoin, primidone, and ethosuximide were developed in the early 20th century. More than 10 types of antiepileptic drugs have been developed since the 1990s, and there are now more than 20 antiepileptic drugs in active clinical use. The choice of antiepileptic drugs is based on the clinical features of the seizure types, electroencephalogram findings, epileptic syndrome, and drug stability. Currently there are 19 antiepileptic drugs approved by the Korean Food and Drug Administration, 18 of which (with the exclusion of brivaracetam) are covered by the National Health Insurance Service in Korea. We reviewed the selection of antiepileptic drugs according to the classification of epileptic seizures.

Topiramate and cognitive impairment: evidence and clinical implications

Topiramate is an antiepileptic drug (AED) with multiple mechanisms of action that has been shown to be effective in a number of neuropsychiatric disorders. However, cognitive dysfunction is frequently observed in such patients, often representing a relevant challenge in their management. Moreover, there is a long-held recognition that AEDs may profoundly affect cognitive functions. This paper reviews available data on cognitive adverse events in patients with neurological disorders treated with topiramate, discussing the role of different contributing factors such as the pharmacological properties of the drug, the specific features of the brain disorder, and other variables pertinent to the discussion. All studies agree that up to 10% of patients may complain of treatment-emergent adverse events on cognition. Such problems occur early during treatment (i.e. within 6 weeks) and emerge in a dose-dependent fashion, suggesting that such prevalence may be significantly reduced using the drug in monotherapy and adopting individualized doses and titration schedules. The magnitude of the problem is generally mild to moderate and the subjective perception of the patient needs to be taken into account. In fact, apart from language problems, data are not conclusive. Comparisons with new AEDs are limited to levetiracetam and lamotrigine, in both cases generally disfavoring topiramate, while data regarding first-generation AEDs show clear differences only for verbal fluency.

Adaptive behavior outcomes in infants treated with adjunctive topiramate

Data from two global studies (6-week open-label, phase 1 study; 20-day double-blind, phase 3 study) and their 1-year open-label extensions were pooled to assess long-term effects of adjunctive topiramate on adaptive behavior in infants with clinical or video-electroencephalographic evidence of refractory, partial-onset seizures. The primary safety and efficacy results of adjunctive topiramate treatment were reported previously. We report the changes in adaptive behavior of infants, based on Vineland Scales of Adaptive Behavior. Of 284 infants (mean [S.D.] age, 12 [6.3] months) enrolled, 89% (n = 252) manifested partial-onset seizures, and 41% (n = 116) manifested clinically relevant, symptomatic etiologies at pretreatment baseline. Overall, Vineland scores were below average at pretreatment baseline. The most frequently used concomitant antiepileptic drugs included valproic acid (59%), phenobarbital (31%), and carbamazepine (19%). The most common treatment-emergent cognitive and neuropsychiatric adverse events included anorexia (35%) and somnolence (27%). A clinically significant decline (approximately 15 points, or 1 S.D.) occurred in both Vineland Scales composite (mean change, -14.0) and domain standard scores from pretreatment baseline to open-label extension endpoint. However, individual domain raw scores increased, indicating that infants progressed in acquisitions of adaptive skill, but at a slower rate than the normative population.

Pharmacokinetic-pharmacodynamic assessment of topiramate dosing regimens for children with epilepsy 2 to <10 years of age

PURPOSE

To identify and validate the efficacious monotherapy dosing regimen for topiramate in children aged 2 to <10 years with newly diagnosed epilepsy using pharmacokinetic-pharmacodynamic (PK-PD) modeling and simulation bridging.

METHODS

Several models were developed in pediatric and adult populations to relate steady-state trough plasma concentrations (C(min)) of topiramate to the magnitude of clinical effect in monotherapy and adjunctive settings. These models were integrated to derive and support the monotherapy dosing regimen for pediatric patients.

KEY FINDINGS

A two-compartmental population PK model with first-order absorption described the time course of topiramate C(min) as a function of dosing regimen. Disposition of topiramate was related to age, body weight, and use of various concomitant antiepileptic drugs. The PK-PD model for monotherapy indicated that the hazard of time to first seizure decreased with increasing C(min) and time since randomization. Higher baseline seizure frequency increased risk for seizures. Age did not significantly influence hazard of time to first seizure after randomization to monotherapy. For adjunctive therapy, the distribution of drug and placebo responses was not significantly different among age groups. Based on the available PK-PD modeling data, the dosing regimen expected to achieve a 65-75% seizure freedom rate after 1 year for pediatric patients age 2-10 years is approximately 6-9 mg/kg per day.

SIGNIFICANCE

This analysis indicated no difference in PK-PD of topiramate between adult and pediatric patients. Effects of indication and body weight on PK were adequately integrated into the model, and monotherapy dosing regimens were identified for children 2-10 years of age.

Treatment strategies for focal epilepsy

BACKGROUND

Treatment strategies for focal epilepsy need to take account of the phase and severity of the seizure disorder, comorbidity, gender and age.

METHODS

Expert review and evaluation of major studies on the treatment of focal epilepsy.

RESULTS

Complete seizure control is most often achieved with antiepileptic drug (AED) monotherapy. In the choice of AED, possible unfavourable endocrine, cognitive or psychiatric adverse effects and their interaction with the non-seizure manifestations of focal epilepsy have to be considered. In women teratogenic risks associated with AED may be relevant. If complete seizure control cannot be achieved with the first three steps of AED treatment, epilepsy surgery becomes the most likely treatment modality to provide complete seizure control. It is proposed that AED combination treatment should be limited to two or three agents to minimize the risk of side effects, especially negative effects on cognition.

CONCLUSIONS

Recent developments in the treatment of focal epilepsy have made it easier to tailor AED therapy to patients' demographic and clinical profile.

Exploring efficacy and tolerability outcomes in patients with difficult-to-treat epilepsy receiving adjunctive topiramate at different titration rates--an exploratory study

OBJECTIVE

To compare rapid vs regular titration of topiramate concerning efficacy and safety.

MATERIALS AND METHODS

Open-label, prospective, single-center study exploring efficacy and tolerability of two adjunctive dosing regimens of topiramate (TPM) in adult patients with difficult-to-treat epilepsy. Based on investigator judgment, 21 of 50 consecutive patients received a rapid titration (starting dose 50 mg/day, stepwise increase with 50 mg/day after 3 days each until reaching the target dose), while the other 29 patients received titration according to the German prescribing information (starting dose 25 mg/day, stepwise increase with 25-50 mg/day every 7 days). Patients were observed until the target dose was reached and 3 months thereafter.

RESULTS

Mean final dosages were 136 mg/day (regular titration) and 213 mg/day (rapid titration). Efficacy and tolerability measures did not differ significantly. Forty-six percent of all patients experienced a seizure reduction of > or = 50%; 14% became seizure free. No serious adverse events occurred. The most common adverse effects were tiredness (20%), memory and language difficulties (18% each), slowness in thinking and speech (10%), psychomotor disturbance (8%) and paresthesia (8%).

CONCLUSIONS

This study suggests that rapid and conventional titration generate similar tolerability, safety and effectiveness in selected patients.