Felbamate in the Treatment of Lennox-Gastaut Syndrome: Results of a 12-Month Open-Label Study Following a Randomized Clinical Trial

Summary: Felbamate (FBM) is a new antiepileptic drug (AED) that has been evaluated in partial seizures and in the Lennox-Gastaut syndrome (LGS). When tested against placebo in an add-on, randomized, double-blind trial in 73 children with LGS, FBM significantly reduced the frequencies of astatic (atonic) seizures and generalized tonic-clonic seizures plus total seizure counts. In addition, FBM-treated subjects improved significantly on a parent-rated global evaluation and had fewer injuries. Overall, ˜50% of subjects experienced a 50% or greater reduction in total seizure frequency and a dose-response relationship was apparent. The improvement that occurred in the double-blind study has been sustained for at least 12 months in subsequent open-label follow-up studies. In the first month of FBM treatment, 62% of the subjects who had previously received placebo had a reduction in total seizure frequency of >50%. By the 12-month follow-up point, approximately half of the patients had a 50% reduction in total seizure count. Astatic seizures responded even better, with two-thirds of patients having a reduction of >50% in astatic seizure frequency after 12 months of treatment. Based on adverse experience reports thus far, FBM appears to be well tolerated. FBM is the first drug to be shown effective in the LGS in randomized controlled trials. Although few subjects with LGS became seizure free, the frequency of the most severe seizure types decreased and the patients' global functioning improved.     

Felbamate monotherapy: controlled trial in patients with partial onset seizures.

Felbamate (FBM) monotherapy was evaluated in 44 patients with uncontrolled partial onset seizures in a unique, single-center, randomized, double-blind, parallel-group trial. During the 56-day baseline period, patients were required to have at least 8 seizures and to be receiving only one standard antiepileptic drug (AED) at a therapeutic level; a second AED was allowed if at a subtherapeutic level. Patients were randomized to valproate (VPA), 15 mg/kg, or to FBM, 3,600 mg/day. In the treatment phase, previous AEDs were discontinued by study day 28 (by one-third decrements on study days 1, 14, and 28). Study end points were completion of 112 study days or the fulfilling of escape criteria. Criteria for escape relative to baseline were: two-fold increase in monthly seizure frequency, two-fold increase in highest 2-day seizure frequency, single generalized tonic-clonic seizure (GTC) if none occurred during baseline, or significant prolongation of GTCs. The predetermined primary efficacy variable was the number of patients escaping in each treatment group. Nineteen patients on VPA and 3 on FBM met escape criteria (p less than 0.001, chi-square test). When overall seizure frequency among study completers was compared with baseline, the FBM group had a 50 to 65% reduction in seizure frequency. FBM adverse experiences were all mild or moderate in severity, and the incidence of adverse experiences was lower in monotherapy. FBM monotherapy was effective in the treatment of partial onset seizures with or without generalization and demonstrated a favorable safety profile.     

Felbamate in the Treatment of Refractory Partial-Onset Seizures

Summary: Felbamate (FBM) is a new antiepileptic drug (AED) that has been tested in open and controlled studies in patients with therapy-refractory partial-onset seizures. Proof of efficacy is based on results of five controlled studies (three with polytherapy and two with monotherapy). In two of the three polytherapy studies, a classic placebo crossover design was used. The third study used a novel design evaluating the efficacy of FBM in a placebo-controlled parallel design in patients completing an evaluation for epilepsy surgery. The primary efficacy variable in this study was the number of patients who experienced a fourth seizure before the end of the study. Forty-six percent of patients randomized to FBM stopped treatment prematurely because of the occurrence of a fourth seizure compared with 88% randomized to placebo. Two studies investigating the efficacy in monotherapy were performed. Both studies used an identical trial design comparing FBM with a low dosage of valproate (VPA). The efficacy of FBM was found to be superior to the low-dosage VPA for both studies. Open long-term follow-up studies have confirmed the long-term efficacy of FBM for up to 12 months. Overall, FBM was well tolerated in both poly- and monotherapy.     

Clinical Efficacy of New Antiepileptic Drugs in Refractory Partial Epilepsy: Experience in the United States With Three Novel Drugs

Summary: A number of new antiepileptic drugs (AEDs), including topiramate (TPM), felbamate (FBM), and gabapentin (GBP), are approved or believed to be close to approval for marketing in the United States. Key efficacy findings for these AEDs in refractory partial epilepsy were reviewed. Large and significant drug-placebo differences were observed with TPM in two large dose-finding trials conducted in the United States. The minimal effective dose of TPM in the population studied was determined to be approximately 200 mg/day, and doses above 600 mg/day produced good efficacy but little incremental benefit versus the lower dosages for the overall study population. FBM is active in partial epilepsy, although seizure reduction is less marked and drug interactions complicate the findings. GBP is also active in this population, but only the 1,800 mg/day dosage was significantly better than placebo with respect to percent re-sponders. It may be useful to explore higher dosage ranges for both FBM and GBP if they can be well tolerated.     

Felbamate: Successful Development of a New Compound for the Treatment of Epilepsy

Summary: Felbamate (FBM) is an effective and safe novel antiepileptic drug (AED) for add-on treatment in adults with refractory partial seizures as shown in three pivotal controlled trials. In addition, FBM is effective and safe in monotherapy in adults with refractory partial seizures. FBM is also effective and safe as add-on therapy for children and adults with refractory Lennox-Gastaut syndrome. The effective daily dosage is ˜30–45 mg/kg divided into three or four doses with resulting plasma concentrations of 50–80 mg/L. The safety profile of FBM is limited to mild gastrointestinal complaints, insomnia, and nonspecific CNS symptoms. Six pivotal controlled trials, with both classic and innovative design, showed that FBM is a useful AED.     

Felbamate for refractory absence seizures

We treated 10 patients (aged 5–37 years) with medically refractory absence seizures with felbamate (FBM). Average duration of absence seizures was 16.2 years. All patients continued to have absence seizures at maximally tolerated doses of valproic acid and/or ethosuximide. At maximal FBM dosage (45 mg/kg/day or 3,600 mg/day), there was at least a 65% reduction in absence seizure frequency in eight patients; in four, there was a > 95% reduction. Mean duration of FBM therapy is 16.2 months (range, 5–31 months). Nine patients remain on FBM. Two patients are on FBM monotherapy; seven others are on FBM and one or two other antiepileptic drugs. FBM was discontinued in one patient who developed severe insomnia followed by a return to baseline absence seizure frequency after an initial good response, and an increase in generalized tonic-clonic seizures (GTCS). Three other patients also had a history of GTCS; in one there has been no significant change, whereas two have not had a GTCS during FBM therapy. Eight patients continue to have a clinically meaningful reduced absence seizure frequency, and eight patients reported fewer adverse effects with their current regimen including FBM. Tachyphylaxis to the antiabsence efficacy was observed in four cases. These preliminary findings suggest that FBM is useful in treating absence seizures.     

Ketogenic diet in patients with Lennox–Gastaut syndrome

PurposeThe ketogenic diet (KD) has been used as an alternative to antiepileptic drugs (AEDs) for patients with refractory epilepsy. Lennox–Gastaut syndrome (LGS) belongs to the group of epileptic encephalopathies that often prove refractory to AED treatment.In this prospective study we assess the efficacy and tolerability of the KD in patients with LGS.MethodsBetween March 1, 1990 and April 1, 2013, 61 patients who met diagnostic criteria of LGS were seen at our department. Twenty of them were placed on the KD and followed for a minimum of 16 months.ResultsThe children had previously received a mean of 6.5 different AEDs and were on a mean of 2.5 AEDs when the diet was started. Eighteen months after initiating the diet, fifteen of the initial patients (75%) remained on the diet; three patients (15%) were seizure free, three (15%) had a 75–99% decrease in seizures, two (10%) had a 50–74% decrease in seizures, and the remaining seven children (35%) had a <50% decrease in seizures. Three seizure-free patients were tapered off the diet after remaining seizure free. In the three patients who had a 75–99% decrease in seizures AEDs were reduced.ConclusionThe KD is an effective and well-tolerated treatment option for patients with LGS, not only for those with cryptogenic, but also for those with structural LGS. The diet should be considered early in the course of this syndrome.     

Role of rufinamide in the management of Lennox-Gastaut syndrome (childhood epileptic encephalopathy)

Rufinamide, a triazole derivative that is structurally distinct from currently marketed antiepileptic drugs (AEDs), is in development for the adjunctive treatment of Lennox-Gastaut syndrome (LGS) in children and adults. Rufinamide is well absorbed after oral administration, demonstrates low protein binding, and is metabolized by enzymatic hydrolysis without involvement of cytochrome P450 enzymes, conferring a low drug interaction potential. In a randomized, double-blind trial involving 138 adult and pediatric patients with LGS, compared with placebo, rufinamide 45 mg/kg/day resulted in significantly superior reductions in drop attacks (median change −42.5% vs +1.4% with placebo) and total seizures (−32.1% vs −11.7% with placebo), accompanied by significantly higher responder rates. These results are comparable with findings reported for other AEDs in randomized, controlled clinical trials in patients with LGS. Rufinamide produced statistically significant seizure reduction which was maintained during long-term therapy and accompanied by good tolerability. The most frequently reported adverse events from a pooled safety database evaluating short- and long-term therapy were headache (22.9% and 29.5%), dizziness (15.5% and 22.5%) and fatigue (13.6% and 17.7%). Rufinamide therefore presents a favorable efficacy and tolerability profile and is a promising candidate for the adjunctive therapy of LGS.     

Characteristics of patients initiated on the new antiepileptic drugs: a PADS study

Whereas randomized controlled trials remain a standard for evaluating and comparing efficacy and safety of the new antiepileptic drugs (AEDs), postmarketing drug research offers a useful means of comparing efficacy and safety of new AEDs. However, differences in baseline characteristics of patients in different drug groups create the potential for bias in drug comparison studies. In this study, baseline demographic characteristics of 1,386 patients initiating lamotrigine (LTG), tiagabine (TGB), or topiramate (TPM) were compared to identify patient characteristics that may influence AED use in epilepsy patients. Data were collected at 14 epilepsy centers and included medications, seizure types and syndromes, and prior adverse events. There were 402 patients in the LTG group, 725 TPM, and 259 TGB. The groups differed both in their number of concurrent AEDs (p<0.001) and in their number of prior AEDs (p<0.01). There was no difference in proportion with partial versus generalized epilepsy syndromes. The groups differed in the proportions of patients with complex partial seizures (p=0.049), primary generalized tonic-clonic seizures (p=0.01), and myoclonic seizures (p=0.03). Baseline behavioral adverse event rate was lowest in patients initiating TPM (p<0.01); LTG patients had the lowest rate of prior AED-related rash (p=0.02). There was no relationship between AED assignment and patient age, age of epilepsy onset, epilepsy duration, institutionalization status, gender, or psychiatric history. Numerous epidemiological differences were identified among patients placed on the new AEDs, including current and prior AED profiles, seizure types, and prior adverse event history. Accounting for these differences is of crucial importance because they may bias conclusions of nonrandomized post-marketing trials comparing the drugs.     

Efficacy and Tolerance of Long-Term, High-Dose Gabapentin: Additional Observations

Summary: Gabapentin (GBP) has shown antiepileptic efficacy and good tolerance in clinical trials. Much remains to be learned about its clinical use. As a participating center in the US Gabapentin Study Group, we report observations that have practical implications for patient management. Twenty-three patients with intractable partial-onset seizures initiated open-label treatment after a blinded placebo-controlled add-on dose efficacy study. In the titration phase, GBP and concurrent antiepileptic drugs (AEDs) were adjusted to achieve optimal efficacy on maximally tolerated GBP doses. Nine patients had no significant improvement in seizure control and discontinued GBP. The remaining 14 patients were observed while treated long-term with stable-dose GBP and concurrent AEDs. Improvement was maintained as long as patients were followed: ≤4 years. The protocol-allowed upper dose limit, 2,400 mg/day, was well tolerated by 16 of 23 patients, indicating that higher doses may be tolerated. GBP discontinuation did not cause rebound increases in seizure frequency. The most common adverse events (AEs) (in 14 of 23) were similar to those induced by concurrent AEDs and responded to reduction of concurrent AEDs. Many patients reported positive psychostimulatory effects. These observations extend previous findings indicating that GBP is an effective and well-tolerated drug for treatment of partial-onset seizures.     

The long-term use of felbamate in children with severe refractory epilepsy.

The aim of the study was to assess the efficacy and safety of felbamate (FBM) as add-on therapy in pediatric patients with severe uncontrolled seizures during a 3-year follow-up. Thirty-six patients were enrolled between February 1994 and February 1997. Patients suffered from partial epilepsy (n=13), Lennox-Gastaut syndrome (LGS) (n=9), infantile spasms (IS) n=8 or other forms of generalized epilepsy (n=6). FBM was titrated weekly from 15 up to 45 mg/kg. By February 1995, all patients had hematological and biochemical monitoring prior to FBM therapy and every 15 days during the study. The results achieved at different treatment durations were analyzed. Overall efficacy measured as > or =50% reduction in seizure frequency varied during follow-up: 69% at 3 months, progressively decreasing to 66% at 6 months, to 47% at 1 year and 41% of the initial cohort at the end of the study. Most frequent side effects were anorexia, weight loss, urinary retention, somnolence, nervousness and insomnia. FBM controlled a broad spectrum of otherwise refractory seizures. Best results were obtained against simple partial seizures with or without secondary generalization, tonic and atonic seizures. A substantial improvement in seizure control was maintained in one-third of the patients for at least 3 years.     

Felbamate Monotherapy: Implications for Antiepileptic Drug Development

Summary: We studied the effect of felbamate (FBM) monotherapy on seizure rate in patients with partial and secondarily generalized seizures undergoing presurgical monitoring at a single site. The study design was a double-blind placebo-controlled parallel monotherapy trial. Forty patients whose seizures had not been controlled by standard antiepileptic drugs (AEDs) were randomized. Seizure type was confirmed by video-EEG monitoring. All baseline AEDs were discontinued, and patients were drug-free for 5.3 ± 2.4 days before randomization to FBM or placebo. After a 4-day titration, seizures were counted for 14 days. Patients receiving FBM had significantly lower seizure rates, whether all randomized patients, patients who survived titration, or study completers were compared. Eight of 19 placebo patients randomized to placebo, as compared with 13 of 21 receiving FBM, completed the 18-day study. Two FBM patients dropped out due to seizures, and 6 dropped out due to side effects, including anxiety, difficulty sleeping, abdominal discomfort, acute psychosis, and orobuccal dyskinesias. Ten placebo patients met the criteria for premature discontinuation owing to seizures, and 1 had an episode of panic. There was no evidence of hepatic or hematologic toxicity. FBM reduces seizure frequency in patients with localization-related epilepsy.     

Efficacy of gabapentin as adjunctive therapy in a large, multicenter study. The Steps Study Group.

The objective of this study was to determine the efficacy of gabapentin as adjunctive therapy in doses required to achieve the most effective seizure control. There were 2016 patients with partial seizures requiring adjunctive therapy who received gabapentin at doses up to 3600 mg/day in this open-label, multicenter, 16-week study. Of the 1055 patients evaluable for efficacy, 573 received gabapentin < or =1800 mg/day and 482 received > 1800 mg/day as the highest dose received. For the overall efficacy evaluable population, the percentage of patients achieving at least a 50% reduction in seizure frequency was 76.0%; 46.4% of the patients were seizure free. Patients whose highest gabapentin dose did not require > 1800 mg/day had, at baseline, fewer seizures and were receiving fewer concomitant antiepileptic drugs (AEDs) at baseline than those patients requiring > 1800 mg/day. This suggests that patients requiring higher doses of gabapentin were more refractory to drug treatment at the start of the study. Gabapentin was well tolerated at all doses in this study. The results of the study demonstrate that gabapentin is effective as adjunctive therapy in patients with partial seizures whose seizures are inadequately controlled by traditional AEDs.     

Efficacy and Adverse Effects of Established and New Antiepileptic Drugs*

Summary: Antiepileptic drug (AED) selection is based primarily on efficacy for specific seizure types and epileptic syndromes. However, efficacy is often similar for the different AEDs, and other properties such as adverse effects, pharmacokinetic properties, and cost may also be of importance. For idiopathic generalized epilepsies with absence, tonic-clonic, and myoclonic seizures, the AED of choice is valproate (VPA). Secondarily generalized epilepsies with tonic, atonic, and other seizure types are difficult to treat with any single AED or combination of AEds. The AEDs of choice for absence seizures are ethosuximide (ESM) and VPA. For control of primary generalized tonic-clonic seizures, any of the other major AEDs can be effective. If VPA cannot be prescribed, carbamazepine (CBZ), phenobarbital (PB), phenytoin (PHT), or primidone (PRM) may be effective, but ESM or a benzodiazepine (BZD) must be added to control associated absence or myoclonic seizures. The AEDs of first choice for partial epilepsies with partial and secondarily generalized tonic-clonic seizures are CBZ and PHT. Increasing evidence suggests that VPA is a good alternative when CBZ and PHT fail. PB and PRM are second-choice selections because of adverse effects. A combination of two of the five standard AEDs may be necessary to treat intractable seizures, but no studies have been done to indicate an optimal combination. Other epilepsy syndromes such as neonatal and infantile epilepsies, febrile epilepsy, alcoholic epilepsy, and status epilepticus require specific AED treatment. Ultimately, AED selection must be individualized. No “drug of choice” can be named for all patients. The expected efficacy for the seizure type, the importance of the expected adverse effects, the pharmacokinetics, and the cost of the AEDs all must be weighed and discussed with the patient before a choice is made. A number of new AEDs with unique mechanisms of action, pharmacokinetic properties, and fewer adverse effects hold important promise of improved epilepsy treatment.     

Lacosamide as add-on in brain tumor-related epilepsy: preliminary report on efficacy and tolerability

Lacosamide (LCM) is an antiepileptic drug (AED) that has demonstrated a good efficacy in controlling seizures as an add-on in adult epilepsy. To date, there have been no studies on LCM in patients with brain tumor-related epilepsy (BTRE). To evaluate efficacy and tolerability of LCM as an add-on in BTRE, we followed 14 patients suffering from BTRE who had already been treated with other AEDs and who had not experienced adequate seizure control. Eleven patients underwent chemotherapy while being treated with LCM. Mean duration of follow up was 5.4 months (min < 1 max 10 months). Mean seizure number in the last month prior to the introduction of LCM had been 15.4. At last follow-up, the mean seizure number was reduced to 1.9/month. Lacosamide mean dosage was of 332.1 mg/day (min 100 max 400 mg/day). Responder rate was 78.6%. One patient discontinued LCM because of side-effects. There were no other reported side-effects. Preliminary data on the use of LCM in add-on in patients with BTRE indicate that this drug may represent a valid alternative as an add-on in this particular patient population. However, larger samples are necessary in order to draw definitive conclusions.     

Tiagabine Monotherapy in the Treatment of Partial Epilepsy

Summary: Three studies were conducted to assess tiagabine (TGB) hydrochloride monotherapy in patients with partial seizures. The first was a double-blind, placebo-controlled trial of 11 patients (seven TGB, four placebo) undergoing evaluation for epilepsy surgery. Baseline antiepileptic drug (AED) therapy was discontinued abruptly before monotherapy. Although 24-h seizure rates increased during monotherapy in both groups, patients receiving TGB experienced fewer seizures than placebo patients. Subsequent studies (an open-label, dose-ranging study; n = 31 and a double-blind, randomized comparison of 6 and 36 mg/day TGB; n = 102 and 96, respectively) involved discontinuation of baseline AEDs. In the dose-ranging study, 19 of 31 patients (61%) converted to TGB monotherapy, with a mean final dose of 38.4 mg/day (range 24–54 mg/day) in those who completed the study ( n = 12). In the low- vs. high-dosage study, median 4-week complex partial seizure rates decreased significantly in patients from both dose groups who completed the monotherapy period ( p <0.05 compared with baseline). In the intent-to-treat analysis, significantly more patients in the high-dose group experienced a reduction in seizures of at least 50% compared with the low-dose group ( p = 0.038). Overall, the types of adverse events with TGB monotherapy were similar to those observed in add-on trials. These initial trials in difficult-to-treat epilepsy patients indicate that TGB monotherapy may provide a new approach to the treatment of patients with partial seizures refractory to other AEDs.     

Monotherapy trials: prerequisite data.

Is it possible for an antiepileptic drug (AED) to be effective as add-on therapy in refractory epilepsy but ineffective as monotherapy for the same seizure type(s)? If the answer is 'no', why not award a new AED a monotherapy licence once it has been shown to be effective as adjunctive treatment in placebo controlled, dose-ranging studies in patients with difficult-to-control epilepsy? The recent comparative study between carbamazepine and remacemide, however, suggests that subtle pharmacokinetic/pharmacodynamic interactions between established and new AEDs can indicate efficacy in add-on studies that does not necessarily transfer to monotherapy. There is some evidence that an AED whose primary mechanism of action does not involve blockade of voltage-dependent sodium channels may do less well than carbamazepine in terms of efficacy end-points in a double-blind, head-to-head comparison. These observations lead to the conclusion that monotherapy trials are, indeed, required. They should be undertaken after proof of efficacy has been obtained using a single short presurgical AED withdrawal study backed up by a substantive dose-ranging phase III efficacy trial. There is no reason to recommend earlier assessment since the clinical need for new AEDs is in refractory epilepsy. The subsequent monotherapy trial programme should contain elements utilising comparative and withdrawal designs. Sponsors should be able to seek a licence for their drug either as a first choice treatment in newly diagnosed epilepsy or as substitution monotherapy once treatment with at least one other AED has failed.     

Preliminary Observations on Topiramate in Pediatric Epilepsies

Summary: Preliminary results of studies of topiramate (TPM) in children are now available. In a pharmacokinetic study among 18 male and female children, target daily dosages of up to 9 mg/kg/day were evaluated. TPM pharmacokinetics in children were linear. Mean TPM oral clearance (CL/F) was 44–54% higher in children [depending on concomitant antiepileptic drugs (AEDs)] compared with historical data from adults, and steady-state plasma TPM concentrations for the same mg/kg dose were 33% lower in children compared with historical adult data. In a long-term, open-label pilot study of adjunctive TPM therapy in 18 patients with Lennox-Gastaut syndrome, six of the eight patients (75%) still receiving TPM report a greater than 50% reduction in total seizures, with the best results observed in tonic-atonic, atypical absence, and generalized tonic-clonic seizures. Subsequent large double-blind, placebo-controlled trials of adjunctive TPM therapy in Lennox-Gastaut syndrome and refractory partial-onset pediatric epilepsy are ongoing, with high percentages of enrolled patients in both studies completing double-blind treatment and entering long-term TPM open extension trials. A small TPM monotherapy substitution trial in children with well controlled partial onset seizures showed that TPM monotherapeutic substitution can be achieved successfully with an acceptable amount of adverse experiences with a weekly increase of 1 mg/kg/day to a maximal dose of 3 mg/kg/day. These preliminary results suggest that TPM may be a useful new AED in pediatric patients with a variety of seizure disorders.     

Felbamate in the Treatment of Lennox-Gastaut Syndrome

Summary: Felbamate (FBM, Felbatol/Taloxa), a new an-tiepileptic drug (AED), was tested in a placebo-controlled add-on design in 73 patients with therapy refractory Lennox-Gastaut syndrome. Results of the efficacy analysis showed that FBM was statistically significantly more effective (p < 0.05) than placebo for four of five predefined efficacy variables. The total number of seizures, for example, decreased by 26% during treatment with FBM compared with an increase of 5% during placebo (p < 0.001). Retrospective analysis of percentage of patients with specific response rates confirmed results of the predefined efficacy variables. Approximately 50% of patients randomized to FBM obtained at least a 50% reduction in seizure frequency compared with about 15% receiving placebo. In addition, 12-month follow-up data in patients who completed the controlled part of the study confirmed the long-term efficacy of FBM. In general, FBM was well tolerated, with only gastrointestinal symptoms and somnolence seen more often with FBM compared with placebo. FBM is the first compound shown to be effective in a controlled study in patients with Lennox-Gastaut syndrome.     

Clinical Science

Christian E. Elger , Martin J. Brodie , Henning Anhut , Caroline M. Lee , and Jeannette A. Barrett
Pregabalin is an antiepileptic medication introduced in many countries in 2004–2005 for the treatment of partial epilepsy in adults, when administered in combination with other antiepileptic drugs (AEDs). Clinical trials traditionally employ fixed doses throughout, while in clinical practice, the dose of most AEDs is adjusted gradually, with the dual aim of enhancing tolerability and allowing for optimum effective dosing. The current study included a novel flexible dose regimen in which patients were started on the lowest effective dose of 150 mg/day of pregabalin, followed by a stepwise increase in dose for those patients with inadequate seizure control, up to 600 mg/day. The study goal was to compare the stepwise regimen in terms of both efficacy in seizure reduction and tolerability with a fixed high dose regimen of 600 mg/day. To be eligible for the 12-week study, patients (n = 341) had to be receiving at least one other AED and still experiencing at least four partial seizures in the previous 6 weeks. Both pregabalin regimens were highly effective at reducing the frequency of seizures, with reductions of 35% for flexible dose, and 49% for fixed dose, compared to 11% for placebo. Both regimens were well tolerated, with most side effects being mild or moderate. However, 76% of the patients completed the study in the flexible dose group, versus 58% for the fixed dose group, and more had side effects in the fixed dose group. In conclusion, there appears to be a treatment advantage to adjusting the dose of pregabalin within the therapeutic range of 150–600 mg/day, according to the patient's optimal efficacy and tolerability.