Biomedical subjects
Publications and source records attributed to Martin J Brodie.
Sexual dysfunction has been reported in both men and women with epilepsy. Associated factors are diverse but include, among others, antiepileptic drugs. We present the cases of 5 men who reported mild to moderate erectile dysfunction or impotence for the first time when treated with the new antiepileptic drug pregabalin as add-on therapy.
Very few clinical trials have been done in the elderly. This report reviews results of two completed studies and describes one in progress. The largest published study was a United States Veterans Affairs Administration study in newly diagnosed patients with epilepsy. It compared carbamazepine to gabapentin and lamotrigine, and found that, although equivalent in efficacy, the newer antiepileptic drugs (AEDs) were better tolerated. This study also highlighted many of the difficulties in recruiting and retaining elderly patients in studies, the large number of comorbidities, and the problems of distinguishing seizures in the elderly from other symptoms. Another study of new-onset epilepsy suggested that a large percentage of elderly patients respond to initial AED therapy, but side effect profiles differ. More studies are needed to better define the risk/benefit relationships in elderly patients.
BACKGROUND: Old age is the most common time in life to develop epilepsy. Despite this, there are few published data exploring pharmacological outcomes in this population. METHODS: We analyzed outcomes in 117 older patients (median age, 73; range, 65-92) for whom localization-related epilepsy was newly diagnosed and treatment begun at a single center over a 20-year period. RESULTS: Seventy-three (62%) patients became seizure-free for at least 12 months on their first AED, with 30 (26%) failing to respond and 14 (12%) not tolerating the treatment. Following pharmacological manipulation, 93 (79%) patients attained remission, 87 (93%) on monotherapy and 6 (7%) on duotherapy. No individual AED was more likely to confer seizure freedom than any other. Patients attaining remission were more likely to have had fewer pretreatment seizures (P=0.0078) than those who did not obtain full seizure control. CONCLUSION: The prognosis in epilepsy may be better in older than younger people, perhaps reflecting lower lesional epileptogenicity and genetic predisposition.
This report describes the concept for a clinical trial that uses carbamazepine as the gold-standard active control for a study of newly diagnosed patients. The authors describe an endpoint including efficacy and tolerability, and a stopping rule that uses a series of interim analyses in order to reach a conclusion as efficiently as possible without sacrificing reliability.
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Zonisamide (Zonegran) has been used extensively worldwide (>2 million patient-years experience) for the effective treatment of a broad range of epilepsy indications. Four randomised, placebo-controlled trials (duration or=300 mg/day to be efficacious in treating refractory partial seizures in adults. In a pivotal European study, zonisamide 500 mg/day was significantly superior to placebo in reducing the frequency of complex partial seizures (-51% versus -16%), all partial seizures and all seizures, with dose-dependent benefit provided over a 100-500 mg/day dose range. Supporting trials have confirmed significant increases in reduction in median seizure frequency (up to 41%) and responder rates (35-42%) compared with placebo following zonisamide 400-600 mg/day, enabling 20-27% of patients to attain >or=75% reduction in seizure frequency. Pooled data from all four placebo-controlled trials demonstrate an excellent tolerability and safety profile; adverse events are generally of mild-moderate severity with few leading to discontinuation, and incidence of serious adverse events is comparable to placebo. These data support the use of zonisamide in combination with commonly used antiepileptic drugs to provide efficacious and well-tolerated treatment for patients with refractory partial seizures.
This randomized, double-blind, placebo-controlled UK trial evaluated the effect of topiramate as add-on therapy on seizure frequency, seizure severity, and quality of life in patients with epilepsy and intellectual disability. There were three phases: 4 weeks baseline, 18 weeks titration to 200-400 mg topiramate/day (adults) or 5-9 mg/kg/day (children), 12 weeks maintenance. Recruitment was low (88/120); analyses were underpowered. Seizure frequency varied enormously (median 17.7, maximum 1706.2). There was no significant difference in reduction in mean total seizure frequency or number of responders between the groups. Topiramate reduced seizure frequency by >30% from baseline (placebo 1%); post hoc analyses showed a trend toward significance (R ratio, P=0.052). There were no significant differences between the groups with respect to mean seizure severity or other outcome measures. Topiramate was generally well tolerated; body weight (P=0.015) and systolic blood pressure (P=0.043) were reduced. The study suggests that topiramate reduces seizure frequency in patients with epilepsy and intellectual disability without the added burden of behavior effects, and was potentially advantageous to physical well-being.
Most patients reporting more than one well-documented or witnessed seizure require prophylactic antiepileptic (AED) therapy. Those with an underlying brain disorder and/or an abnormal electroencephalogram should probably be treated after their first event. The goal should be maintenance of a normal lifestyle by complete seizure control with no or minimal side-effects. Failure of the first AED due to lack of efficacy implies refractoriness. A policy of consecutive substitutions is unlikely to be an effective strategy. Thus, if the first or second monotherapy improves control but does not produce seizure freedom, an AED with different and perhaps multiple mechanisms of action should be added. Strategies for combining drugs should involve individual assessment of patient-related factors, including seizure type and epilepsy syndrome classifications coupled with an understanding of the pharmacology, side-effects and interaction profile of the AEDs. Reducing the dose of one or more AEDs may help accommodate the introduction of a second or third drug. An orderly approach to the pharmacological management and, when appropriate, surgical investigations for each epilepsy syndrome will optimise the chance of perfect seizure control and help more people achieve safer and more fulfilled lives.
This prospective open-label study used flexible dosing schedules of levetiracetam (LEV) in patients with refractory epilepsy attending a single centre to explore its effectiveness in everyday clinical practice. One hundred and fifty-six patients with uncontrolled localisation-related or idiopathic-generalised epilepsy were prescribed adjunctive LEV following a 3-month baseline. The primary end points were seizure freedom for at least 6 months, > or = 50% reduction (responder) or <50% reduction for 6 months, or discontinuation of LEV due to lack of efficacy, adverse effects or both. Overall, 40 (26%) patients became seizure free on adjunctive LEV, including 8 (40%) with idiopathic-generalised epilepsy. Twenty-five (63%) of the seizure-free patients took 1000 mg LEV per day or less. A further 33 (21%) patients were classified as responders. LEV was withdrawn in 46 (29%) patients (27 adverse effects, 8 lack of efficacy, 11 both). Intolerable sedation, reported by 20 (13%) patients, was the commonest complaint leading to treatment failure. Behavioural side effects led to LEV withdrawal in 7 (5%) patients. LEV is an effective adjunctive treatment for refractory idiopathic and localisation-related epilepsies. Many patients who responded optimally to LEV did so at 1000 mg per day or less.
A total of 558 patients with a range of localization-related epilepsy syndromes starting treatment in a single centre were followed over a period of up to 20 years. Overall, 343 (62%) patients became seizure free for 12 months or more (responders), 92% of whom (57% of total population) remained in remission until the end of follow-up. Only 27 (5%) responders relapsed and subsequently developed refractory epilepsy. The remaining 215 (38%) patients never became seizure free for any 12-month period. There were no significant differences in outcome between cryptogenic (56% remission) and symptomatic (57% remission) epilepsies. Patients with underlying cortical atrophy (71% remission; p<0.05) or cerebrovascular disease (70% remission; p<0.01) did better, while those with traumatic brain injury (35% remission; p<0.001) did worse than the remainder of the symptomatic group. Remission rates in patients with cortical dysplasias (60%), hippocampal atrophy (50%) and primary brain tumors (52%) appeared no different from those with other symptomatic epilepsies. Overall, 20-40% patients with each epilepsy syndrome reported no further seizures after starting AED treatment including 21% with hippocampal atrophy and 33% with cortical dysplasia. More than 50% of patients developing localization-related epilepsy during adolescence or in adulthood had a good outcome. Prognosis in those with underlying hippocampal atrophy or cortical dysplasia was not always bad.
The response to antiepileptic drugs (AEDs) has been examined in 780 adult and adolescent patients with newly diagnosed epilepsy presenting with a range of seizure types and epilepsy syndromes over a 20-year period. Carbamazepine (CBZ, n=312), sodium valproate (VPA, n=315), and lamotrigine (LTG, n=249) were the most common AEDs prescribed as monotherapy. More patients with localization-related epilepsies became seizure free with LTG (63%) than with CBZ (45%, P=0.006) or VPA (42%, P=0.006). For idiopathic generalized epilepsies a greater proportion of patients achieved control with VPA (68%) than with CBZ (31%) or LTG (45%). In particular, more patients with juvenile myoclonic epilepsy responded to VPA (75%) compared with LTG (39%, P=0.014). Seizure freedom was achieved with modest or moderate daily doses (median CBZ 400mg, VPA 1000 mg, (LTG) 150 mg) of all three AEDs in the majority of patients achieving remission. Time to first seizure did not differ among these three drugs when given as first treatment. Adverse effects leading to withdrawal were more frequent with CBZ (16%) than with VPA (7%, P=0.03) or LTG (7%, P=0.018). In patients failing initial monotherapy, response to a combination of two AEDs (27%) was not different from that with alternative monotherapy (32%). The majority of patients with newly diagnosed epilepsy responding to treatment did so rapidly and completely with moderate doses of AEDs, with no differences in time to first seizure.
The present study was designed to assess the effect of the addition of zonisamide (ZNS) on lamotrigine (LTG) disposition and the safety of the combination under steady-state conditions in patients with epilepsy. A secondary objective was to characterize ZNS pharmacokinetics (PK) in the presence of LTG. Twenty subjects (male and female 18 to 55 years old) stabilized on LTG monotherapy (150-500 mg/d) took part in a 2-center, open-label, 1-way drug interaction study. ZNS was gradually increased to 200 mg twice daily over a 3-week period, and 3 PK profiles were performed: on days -7 and -1 to assess the PK of oral LTG administered alone and on day 35, after 14 days of ZNS at the maximal tolerated dose, to evaluate the effect of ZNS on LTG PK and to characterize ZNS PK in the presence of LTG. Eighteen subjects completed the study. Steady-state dosing of ZNS did not significantly affect the mean Cmin (mean +/- SD: 2.8 +/- 1.4 vs 3.5 +/- 2.4 microg/mL), Cmax (5.1 +/- 3.0 vs 5.1 +/- 3.0 microg/mL), AUC0-12 (45.5 +/- 22.6 vs 50.3 +/- 32.1 microg.h/mL), and CL/F (2778.5 +/- 1368.5 vs 3052.1 +/- 2744.9 mL/h) of LTG measured before (day -1) and after (day 35) ZNS administration, respectively. Further, 90% confidence intervals for the geometric mean ratios (day 35/day -1) fell within the no-effect range of 0.80-1.25. The fraction of dose of total and unconjugated LTG excreted in urine was not significantly different between baseline and ZNS treatment, but the renal clearance of LTG decreased significantly with ZNS dosing (P = 0.01). On the other hand, the PK parameters measured for ZNS in the presence of LTG were consistent with an absence of LTG effect on ZNS PK. The coadministration of ZNS and LTG was generally well tolerated. Steady-state safety and PK of LTG and ZNS are not affected significantly when these two drugs are coadministered at clinically relevant doses, indicating that no dosage adjustment of either drug should be required when they are used in combination.
PURPOSE: To evaluate the safety and efficacy of zonisamide (ZNS) as adjunctive treatment in patients with refractory localization-related epilepsy. METHODS: This was a double-blind, placebo-controlled study of adjunctive ZNS in 351 patients with refractory partial seizures receiving a stable regimen of one to three antiepileptic drugs (AEDs). Patients were randomized to placebo or ZNS, 100 mg, 300 mg, or 500 mg/day (2:1:1:2) after a 12-week baseline. Dose titration was undertaken over a 6-week titration phase, which was followed by an 18-week fixed-dose assessment phase. Primary efficacy parameters were the differences between ZNS, 500 mg/day, and placebo in the change from baseline in frequency of complex partial (CP) seizures during the fixed-dose assessment phase and in the proportion of CP responders (> or =50% decrease from baseline in seizure frequency). Safety and tolerability also were assessed. RESULTS: Compared with placebo, the highest dose of ZNS (500 mg/day) resulted in a significantly greater decrease in CP seizure frequency from baseline (51.2% vs. 16.3%; p < 0.0001) and a significantly higher proportion of CP responders (52.3% vs. 21.3%; p < 0.001). Both ZNS, 500 mg/day, and 300 mg/day were statistically superior to placebo in reducing the frequency of "all seizures" and simple partial (SP) + CP seizures. For all seizures, a significant dose-response relation was observed (p < 0.0001). The most common adverse events were somnolence, headache, dizziness, and nausea during the titration phase and headache and pharyngitis during the fixed-dose assessment phase. CONCLUSIONS: ZNS provides dose-dependent, effective, and generally well-tolerated adjunctive therapy in patients with partial seizures.
The pathogenesis underlying pharmacoresistance in epilepsy is unclear. One of the candidate mechanisms that has attracted growing interest is the limitation of antiepileptic drug (AED) access to the seizure focus by a range of efflux transporters, the prototype of which is P-glycoprotein (P-gp). P-gp is encoded by the multidrug resistance (MDR1 or ABCB1) gene. Predominantly expressed in organs with excretory functions and at blood-tissue barriers, P-gp is thought to act as a physiologic defense by extruding xenobiotics from mammalian cells and affording protection of sensitive organs. The high level of P-gp in the cerebrovascular endothelium is believed to contribute to the functionality of the blood-brain barrier. Overexpression of P-gp causes multidrug resistance in certain cancers. It has been hypothesized that overexpression of P-gp and other efflux transporters in the cerebrovascular endothelium, in the region of the epileptic focus, also may lead to drug resistance in epilepsy. This hypothesis is supported by the findings of elevated expression of efflux transporters in epileptic foci in patients with drug-resistant epilepsy, induction of expression by seizures in animal models, and experimental evidence that some commonly used AEDs are substrates. Conflicting reports suggest a possible association between variants of the MDR1 gene and medical intractability in epilepsy. Further studies to delineate the exact role, if any, of P-gp and other efflux transporters in drug-resistant epilepsy are warranted.
Older antiepileptic drugs continue to play a major role in the treatment of the idiopathic generalized epilepsies. Comparative studies of ethosuximide and valproate have demonstrated equivalence in the treatment of childhood absence epilepsy. Valproate can be regarded as the recommended first-line treatment for juvenile myoclonic epilepsy based on case series reports. Studies in patients with generalized tonic-clonic seizures have not separated out idiopathic from secondary generalized events. Treatment for the other idiopathic generalized epilepsy syndromes lacks evidence other than a few case reports and diverse expert opinion. Further randomized controlled trials of older antiepileptic drugs are recommended to solidify the evidence-based treatment of the idiopathic generalized epilepsies.
PURPOSE: To evaluate pregabalin as add-on therapy for patients with partial seizures administered as fixed dose or as flexible dose adjusted to optimal seizure reduction and tolerability. METHODS: Patients receiving antiepileptic drugs (98.8% between 1 and 3 AEDs; 1.2% on more than 3 AEDs) and experiencing > or =4 partial seizures during the 6-week baseline period and no 4-week seizure-free interval were randomized (1:2:2) to placebo (n = 73), pregabalin fixed dose (600 mg/day BID; n = 137), or pregabalin flexible dose (n = 131; 150 and 300 mg/day for 2 weeks each; 450 and 600 mg/day for 4 weeks each, BID) for 12 weeks. Dosage could be adjusted based on tolerability and maintained when a 4-week seizure-free period was achieved. Primary efficacy parameter was reduction in seizure frequency from baseline. RESULTS: Both pregabalin regimens significantly reduced seizure frequency compared with placebo, by 35.4%, for flexible dose (p = 0.0091) and 49.3% for fixed dose (p = 0.0001) versus 10.6% for placebo, and the fixed-dose group was superior to the flexible-dose group (p = 0.0337). Most adverse events were mild or moderate. Discontinuation rates due to adverse events were 6.8% (placebo), 12.2% (pregabalin flexible dose), and 32.8% (pregabalin fixed dose). Patients receiving pregabalin fixed dose discontinued due to adverse event earlier than other groups. CONCLUSIONS: Pregabalin administered twice daily, either as fixed (600 mg/day), or as flexible (150-600 mg/day) dose, was highly effective and generally well-tolerated as add-on therapy for partial seizures with or without secondary generalization. Lower incidence of adverse events and discontinuations were achieved in patients receiving pregabalin when dosing was individualized to optimize efficacy and tolerability.
Recent evidence suggests that the vast majority of people with epilepsy will respond to their first or second treatment regimen or will be refractory de novo. Two patients with symptomatic epilepsy secondary to underlying cortical dysplasias are presented to illustrate these different scenarios. Clinical observations can provide insights to the processes underlying pharmacoresistance.
PURPOSE: Pregabalin (PGB) is an alpha2-delta ligand with demonstrated efficacy in epilepsy, neuropathic pain, and anxiety disorders. PGB is highly efficacious as adjunctive therapy in patients with refractory partial seizures. METHODS: Given its efficacy as adjunctive therapy, the potential for interaction of PGB with other antiepileptic drugs (AEDs) was assessed in patients with partial epilepsy in open-label, multiple-dose studies. Patients received PGB, 600 mg/day (200 mg q8h) for 7 days, in combination with their individualized maintenance monotherapy with valproate (VPA), phenytoin (PHT), lamotrigine (LTG), or carbamazepine (CBZ). RESULTS: Trough steady-state concentrations of CBZ (and its epoxide metabolite), PHT, LTG, and VPA were unaffected by concomitant PGB administration. Likewise, PGB steady-state pharmacokinetic parameter values were similar among patients receiving CBZ, PHT, LTG, or VPA and, in general, were similar to those observed historically in healthy subjects receiving PGB alone. The PGB-AED combinations were generally well tolerated. PGB may be added to VPA, LTG, PHT, or CBZ therapy without concern for pharmacokinetic drug-drug interactions.