A study of topiramate pharmacokinetics and tolerability in children with epilepsy

The pharmacokinetic and safety profile of topiramate as adjunctive therapy was assessed in pediatric patients with epilepsy in an open-label, 4-week, single-center study. Six children from each of the following age groups were enrolled: 4-7 years, 8-11 years, and 12-17 years. Patients received topiramate 1 mg/kg/day for 1 week, with subsequent progressive weekly increases in dosage to 3, 6, and then 9 mg/kg/day or 800 mg/day, whichever was less. Topiramate oral plasma clearance (CL/F) was independent of dose, and steady-state plasma concentrations increased in proportion to dose. Weight-normalized topiramate CL/F was higher (P = 0.003) in pediatric patients receiving enzyme-inducing concomitant antiepileptic drugs (AEDs) (mean = 70.1 mL/minute/70 kg) than in those not receiving enzyme-inducing AEDs (mean = 33.1 mL/minute/kg). Topiramate CL/F in children was approximately 50% greater than that observed in adults regardless of the type of concomitant AED therapy. Thus steady-state plasma topiramate concentrations for the same mg/kg dose will be approximately 33% lower in pediatric patients than in adult patients. The most frequently reported treatment-emergent adverse events considered related to topiramate therapy included anorexia, fatigue, and nervousness, and no patient discontinued therapy. This study indicates that, in children 4-17 years of age, topiramate has linear pharmacokinetics, 50% higher clearance than in adults, and is generally well tolerated.     

Topiramate concentrations in neonates treated with prolonged whole body hypothermia for hypoxic ischemic encephalopathy

Purpose :  Therapeutic hypothermia reduces mortality and neurologic impairment in neonates with hypoxic–ischemic encephalopathy. Topiramate exerts a neuroprotective effect in asphyxiated neonatal animal models. However, no studies have investigated the association of hypothermia and topiramate, because topiramate pharmacokinetics during hypothermia and the optimal administration schedule are unknown. The influence of hypothermia on topiramate pharmacokinetics was evaluated in asphyxiated neonates treated with prolonged whole-body hypothermia and topiramate.
Methods :  Thirteen term newborns were treated with mild or deep whole body hypothermia for 72 h; all received oral topiramate, 5 mg/kg once a day for the first 3 days of life, and seven had concomitant phenobarbital treatment. Topiramate concentrations were measured on serial dried blood spots.
Results :  Topiramate concentrations were within the reference range in 11 of 13 newborns, whereas concentrations exceeded the upper limit in 2 of 13, both newborns on deep hypothermia. Topiramate concentrations reached a virtual steady state in nine newborns, for whom pharmacokinetic parameters were calculated. Values of topiramate maximal and minimal concentration, half-life, average concentration, and area under the time—concentration curve resulted in considerably higher values than those reported in normothermic infants. With respect to normothermic infants, time of maximal concentration was mildly delayed and apparent total body clearance was lower, suggesting slower absorption and elimination. Pharmacokinetic parameters did not differ significantly between infants on deep versus mild hypothermia and in those on topiramate monotherapy versus add-on phenobarbital.
Conclusion :  Most neonates on prolonged hypothermia treated with topiramate 5 mg/kg once a day exhibited drug concentrations within the reference range for the entire treatment duration.     

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 ≥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.     

Topiramate, carbamazepine, and valproate monotherapy: double-blind comparison in children with newly diagnosed epilepsy

In a novel double-blind trial, topiramate was compared with the investigator's choice of carbamazepine or valproate as first-line therapy in patients as young as 6 years of age with newly diagnosed epilepsy. Among 613 patients enrolled in the trial, 119 (19%) were children or adolescents (6-16 years of age). No differences between fixed doses of topiramate (100 and 200 mg/day) and carbamazepine (600 mg/day) or valproate (1250 mg/day) were observed in efficacy measures: time to exit, time to first seizure, and the proportion of patients who were seizure free during the last 6 months of treatment. Topiramate 100 mg/day (2.0 mg/kg/day in this study population) was associated with the fewest discontinuations owing to side effects. Based on efficacy and tolerability, the recommended target dose for topiramate as first-line therapy in children and adolescents is 100 mg/day.     

Topiramate treatment for SSRI-induced weight gain in anxiety disorders

BACKGROUND: Antidepressants, including selective serotonin reuptake inhibitors (SSRIs), have been associated with significant weight gain, a problem that frequently leads to noncompliance and premature discontinuation of treatment. Topiramate is a novel anticonvulsant that has also been used as a mood stabilizer and augmentation agent in mood disorders. Topiramate has been observed to have an interesting side effect of weight loss in some individuals. In this study, topiramate was added to the treatment regimen of patients with a primary DSM-IV anxiety disorder who had experienced substantial SSRI-induced weight gain, in an attempt to induce weight loss. METHOD: Topiramate was added to SSRI treatment in 15 anxiety disorder patients, starting at a dose of 50 mg/day and titrating up to a target daily dose of 100 mg/day, with a maximum dose of 250 mg/day. Subjects' weight was measured at baseline and after 5 and 10 weeks of treatment. RESULTS: Before topiramate treatment, SSRI-treated subjects in this sample had gained a mean of 13.0 +/- 8.4 kg (28.6 +/- 18.5 lb). After the addition of a mean dose of 135.0 +/- 44.1 mg/day of topiramate for approximately 10 weeks, subjects lost a mean of 4.2 +/- 6.0 kg (9.3 +/- 13.3 lb). CONCLUSION: Topiramate may have a role in managing SSRI-induced weight gain in anxiety disorder patients.     

Topiramate in the treatment of binge eating disorder associated with obesity: a randomized,placebo-controlled trial

OBJECTIVE: Binge eating disorder is associated with obesity. Topiramate is an antiepileptic agent associated with weight loss. The objective of this study was to evaluate topiramate in the treatment of binge eating disorder associated with obesity. METHOD: For this 14-week, double-blind, flexible-dose (25-600 mg/day) topiramate trial, 61 outpatients (53 women, eight men) with binge eating disorder who were obese (body mass index >/=30 kg/m(2)) were randomly assigned to receive topiramate (N=30) or placebo (N=31). The primary efficacy measure was binge frequency. The primary analysis of efficacy was a repeated-measures random regression with treatment-by-time as the effect measure. RESULTS: Compared with placebo, topiramate was associated with a significantly greater rate of reduction in binge frequency, binge day frequency, body mass index, weight, and scores on the Clinical Global Impression severity scale and the Yale-Brown Obsessive Compulsive Scale (modified for binge eating). Topiramate was also associated with significantly greater reductions in binge frequency (topiramate: 94%, placebo: 46%) and binge day frequency (topiramate: 93%, placebo: 46%) and with a significantly higher level of response than placebo. The mean weight loss for topiramate-treated subjects who completed the study was 5.9 kg. Median topiramate dose was 212 mg/day (range=50-600). Nine patients (three receiving placebo, six given topiramate) discontinued because of adverse events. The most common reasons for discontinuing topiramate were headache (N=3) and paresthesias (N=2). CONCLUSIONS: Topiramate was efficacious and relatively well tolerated in the short-term treatment of binge eating disorder associated with obesity.     

Topiramate Pharmacokinetics in Infants

PURPOSE: This study's goal was to provide preliminary data on the pharmacokinetics of topiramate (TPM) in a cohort of infants (younger than 4 years) participating in an open-label trial of TPM in refractory infantile spasms. METHODS: The pharmacokinetics of TPM were assessed in infants receiving a stable TPM dose for >7 days during the extension phase of this trial. Blood samples were drawn just before and 0.5. 1, 1.5, 2, 4, 6, 8, and 12 h after the morning TPM dose. TPM plasma concentrations were determined by fluorescence polarization immunoassay. The noncompartmental analysis module of WinNonlin was used to calculate individual patient pharmacokinetics profiles. RESULTS: Five infants (ages, 23.5-29.5 months) formed the study cohort. These infants had been given TPM for a median of 9 months (range, 6-11 months) and were currently receiving between 11 and 38.5 mg/kg/day TPM. One was receiving TPM monotherapy, whereas four were taking concomitant antiepileptic medications (AEDs; n = 2, enzyme-inducing agents; n = 2, non-enzyme-inducing drugs). TPM pharmacokinetics in infants appears to be linear. In this cohort, mean TPM plasma clearance (CL/F, 66.6+/-27.4 ml/h/kg) was slightly higher than that reported for children and adolescents and therefore substantially higher than that reported for adults. TPM CL/F was higher and the calculated half-life shorter in the infants receiving concomitant enzyme-inducing AEDs. CONCLUSIONS: Based on this small cohort of patients, it appears that infants may require significantly larger TPM doses, based on weight, than children, adolescents, or adults. Titration to effect and not absolute TPM dose should guide therapy in this age group.     

A new potential AED, carisbamate, substantially reduces spontaneous motor seizures in rats with kainate-induced epilepsy

Purpose: Animal models with spontaneous epileptic seizures may be useful in the discovery of new antiepileptic drugs (AEDs). The purpose of the present study was to evaluate the efficacy of carisbamate on spontaneous motor seizures in rats with kainate‐induced epilepsy. Methods: Repeated, low‐dose (5 mg/kg), intraperitoneal injections of kainate were administered every hour until each male Sprague‐Dawley rat had experienced convulsive status epilepticus for at least 3 h. Five 1‐month trials (n = 8–10 rats) assessed the effects of 0.3, 1, 3, 10, and 30 mg/kg carisbamate on spontaneous seizures. Each trial involved six AED‐versus‐vehicle tests comprised of carisbamate or 10% solutol‐HS‐15 treatments administered as intraperitoneal injections on alternate days with a recovery day between each treatment day. Results : Carisbamate significantly reduced motor seizure frequency at doses of 10 and 30 mg/kg, and caused complete seizure cessation during the 6‐h postdrug epoch in seven of the eight animals at 30 mg/kg. The effects of carisbamate (0.3–30 mg/kg) on spontaneous motor seizures appeared dose dependent. Conclusions: These data support the hypothesis that a repeated‐measures, crossover protocol in animal models with spontaneous seizures is an effective method for testing AEDs. Carisbamate reduced the frequency of spontaneous motor seizures in a dose‐dependent manner, and was more effective than topiramate at reducing seizures in rats with kainate‐induced epilepsy.     

Topiramate for the treatment of infantile spasms

Topiramate is a new antiepileptic drug with a broad spectrum of efficacy. Reports on the use of topiramate for treatment of infantile spasms are limited. We prospectively followed 15 children with recently diagnosed infantile spasms treated with topiramate for efficacy and tolerability. Twelve patients had symptomatic infantile spasms, and two patients had cryptogenic infantile spasms. Topiramate was started at a dose of 3 mg/kg/day and titrated up to a dose of 27 mg/kg/day in 2 to 3 weeks. The primary efficacy measure was comparison of the seizure rate during the 2-week baseline with the median seizure rate during the first 2 months of treatment with topiramate. We also compared baseline electroencephalograms (EEGs) with post-treatment EEGs. The median seizure rate reduction during the first 2 months of treatment was 41% (P = .002). Three patients became spasm free (20%), five had > 50% reduction, and three had at least 25% reduction. Four patients did not respond. Three of 15 patients had clearing of hypsarrhythmia. Topiramate was generally well tolerated, with irritability being the most common side effect. Topiramate was efficacious and well tolerated; one patient discontinued the medication because of adverse effects. (J Child Neurol 2006;21:17-19).     

Treatment of bulimia nervosa with topiramate in a randomized, double-blind, placebo-controlled trial, part 1: improvement in binge and purge measures

BACKGROUND: This randomized, double-blind, placebo-controlled trial was designed to assess the efficacy and safety of topiramate in bulimia nervosa. METHOD: Patients with DSM-IV bulimia nervosa were randomly assigned in equal proportions to receive topiramate (N = 35) or placebo (N = 34) for 10 weeks (between April 1999 and Dec. 2000). Topiramate treatment was started at 25 mg/day and titrated by 25 to 50 mg/week to a maximum of 400 mg/day. The primary efficacy measure was mean weekly number of binge and/or purge days. Related outcome measures included mean weekly number of binge days and binge frequency, as well as mean weekly number of purge days and purge frequency. RESULTS: Sixty-four outpatients (33 placebo, 31 topiramate) were included in the intent-to-treat analysis. The median topiramate dose was 100 mg/day (range, 25-400 mg/day). Mean +/- SD baseline number of weekly binge and/or purge days was 5.0 +/- 1.6 for topiramate patients and 5.1 +/- 1.5 for placebo patients. The primary efficacy measure, mean weekly number of binge and/or purge days, decreased 44.8% from baseline with topiramate versus 10.7% with placebo (p =.004). The mean weekly number of binge days decreased 48.2% with topiramate versus 17.7% with placebo (p =.015), and mean binge frequency decreased 49.2% with topiramate versus 28.0% with placebo (p =.071). The mean weekly number of purge days decreased 43.4% with topiramate versus 16.6% with placebo (p =.016), and mean purge frequency decreased 49.8% with topiramate versus 21.6% with placebo (p =.016). Three patients (2 placebo, 1 topiramate) discontinued from the trial due to adverse events. CONCLUSION: Topiramate was associated with significant improvements in both binge and purge symptoms in this study population and represents a potential treatment for bulimia nervosa.     

Topiramate in Bipolar and Schizoaffective Disorders: Weight Loss and Efficacy

BACKGROUND: Although useful in bipolar disorder, mood stabilizers, such as lithium, divalproex sodium, and carbamazepine, can cause significant weight gain. METHOD: We conducted a retrospective chart review of 5 patients with DSM-IV bipolar disorder or schizoaffective disorder who were treated with topiramate as adjunctive therapy or monotherapy. RESULTS: All 5 patients had a good response to treatment at a mean topiramate dose of 195 mg/day (range, 100-375 mg/day). All patients lost a substantial amount of weight on topiramate treatment. The average weight loss was 22 lb (10 kg; range, 8-56 lb [4-25 kg]). None of the patients discontinued topiramate because of side effects. CONCLUSION: Topiramate may represent a valuable alternative to existing mood stabilizers, either as an adjunct or as monotherapy in patients with bipolar disorder or schizoaffective disorder.     

Therapeutic doses of topiramate are not toxic to the developing rat brain

Antiepileptic drugs (AEDs) used to treat seizures in pregnant women, infants, and young children may cause cognitive impairment. One of the implicated mechanisms is enhancement of apoptotic neuronal death, which occurs physiologically in the developing brain. We investigated whether topiramate, one of the newer antiepileptic drugs, has neurotoxic properties in the developing rat brain. Topiramate slightly but significantly enhanced apoptotic neuronal death in the 7-day-old rat brain at doses of 50 mg/kg and above. These doses are several folds higher than reported ED(50) doses in infant rodent seizure models that respond to topiramate. Electron microscopy confirmed that dying neurons following topiramate treatment displayed the same morphological features as neurons undergoing physiological cell death during development. When compared to the neurotoxicity profile of phenytoin, valproate, and phenobarbital, the separation between the effective anticonvulsant dose and the neurotoxic dose was greater for topiramate and the neurotoxic effect was lower.     

Effect of Topiramate on the Pharmacokinetics of an Oral Contraceptive Containing Norethindrone and Ethinyl Estradiol in Patients with Epilepsy

Summary: Purpose: Because enzyme-inducing antiepileptic drugs (AEDs) can affect pharmacokinetics of oral contraceptives and thereby cause contraceptive failure, the potential effect of topiramate, a new AED, on the pharmacokinetics of the combination oral contraceptive norethindrone/ethinyl estradiol was evaluated. Methods: Twelve women receiving stable valproic acid (VPA) monotherapy for epilepsy received a combination norethindrone 1.0 mg/ethinyl estradiol 35-μg tablet daily for 21 days followed by seven daily doses of inert tablets for four 28-day cycles. After a baseline cycle (cycle 1), topiramate 100, 200f and 400 mg every 12 h was administered in cycles 2 through 4, respectively. Serial blood samples were obtained on day 20 of each cycle and were analyzed for norethindrone, ethinyl estradiol, and progesterone by using validated radioimmunoassay methods. Results: Compared with cycle 1, none of the norethindrone pharmacokinetic parameters changed significantly in the presence of topiramate, 100–400 mg every 12 h. Individual patient serum progesterone concentrations measured during each cycle were at or close to the limit of quantification with no apparent differences among cycles. However, mean area under the concentration-versus-time curve over the 24-h period (AUC_0–24) values for ethinyl estradiol were 18–30% lower in cycles 2 through 4 compared with cycle 1 (p 0.05 for all pairs), whereas mean oral serum clearance (CL/F) values were 14.7–33.0% higher (p 0.05 for cycles 2 and 4 vs. cycle 1). Mean time of peak concentration (T_max values determined during topiramate therapy were not significantly different from those at baseline. Conclusions: When prescribing an oral contraceptive for patients receiving topiramate, clinicians should consider initial therapy with an agent containing 235 μg of ethinyl estradiol.     

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.     

The efficacy and side effects of topiramate on refractory epilepsy in infants and young children: a multi-center clinical trial.

OBJECTIVES: This study has been conducted to assess the efficacy and safety of topiramate in refractory epilepsies in infants and young children. METHODS: A prospective clinical trial was performed in three tertiary care hospitals, on 47 children aged 6-60 months with refractory epilepsy. Topiramate was added to at least two baseline anti-epileptic drugs. The efficacy was rated according to seizure type, frequency and duration. RESULTS: Children with refractory epilepsy were classified according to their clinical, neuro-imaging, and neurophysiological profile into infantile spasms (IS) (9 cases, 19%), Lennox-Gastaut syndrome (LGS) (25 cases, 53%) and other epilepsies (13 cases, 28%). Children were also classified into cryptogenic and symptomatic epilepsy. Topiramate was introduced as add-on therapy in a daily dose of 1 mg/kg/day for 2 weeks, followed by increments of 1-3 mg/kg/day at 2-week intervals, up to a maximum of 10 mg/kg/day. After a minimum treatment period of 6 months, 28 (60%) of the children had a satisfactory response (completely seizure free, or more than a 50% seizure reduction). The remaining 19 children (40%) had an unsatisfactory response (50% or less reduction in seizure frequency, no change or increased seizure frequency). Topiramate appeared to be equally effective in infantile spasms, Lennox-Gastaut syndrome and children with other types of epilepsy, with no significant difference between those with a satisfactory and an unsatisfactory response (p=0.089). There was also no significant difference in response between patients with cryptogenic and symptomatic epilepsy (p=0.360). Mild to moderate adverse effects, mainly somnolence, anorexia and nervousness, were present in 25 (53%) of children. One of the children developed hypothyroidism. CONCLUSION: Although the long term safety and possible adverse effects of topiramate have not been fully established in infants and young children, this study has shown that it is a useful option for children with frequent seizures unresponsive to standard anti-epileptic drugs.     

Low-dose topiramate in adults with treatment-resistant partial-onset seizures

OBJECTIVES: Based on dose predictions from animal and human volunteer studies, most patients enrolled in initial randomized controlled trials of topiramate as adjunctive therapy in adults with partial-onset seizures were randomized to >or= 600 mg/day topiramate. Subsequent experience suggests that dosage needs were overestimated. This double-blind, placebo-controlled study evaluated 200 mg/day topiramate in adults with treatment-resistant partial-onset seizures receiving a concurrent enzyme-inducing antiepileptic agent (carbamazepine). MATERIALS AND METHODS: After a 4-week baseline, 263 adults receiving carbamazepine who had at least three partial-onset seizures during the baseline period were randomized to placebo or one of two topiramate 200 mg/day treatment arms: topiramate escalated weekly 25 mg/day(8-week escalation) or 50 mg/day(4-week escalation). Therapy was then maintained for the remainder of the 12-week double-blind study. RESULTS: Median percent reduction in seizure frequency from baseline to study end was 44% with topiramate and 20% with placebo (P or=10% incidence in topiramate-treated patients) were somnolence, fatigue, paresthesia, nervousness and anorexia; 8% of topiramate-treated patients and 2% of placebo-treated patients discontinued because of adverse events. As a result of the low incidence of adverse events, differences between titration rates in terms of tolerability were not detected. CONCLUSION: Topiramate 200 mg/day is an appropriate target dose as adjunctive therapy in adults with treatment-resistant partial-onset seizures, even when receiving an enzyme-inducing agent; 100 mg/day also appears to be effective. A significant therapeutic effect may be seen in the second week of treatment with a dose of 100 mg/day.     

Role of topiramate in adults with intractable epilepsy, mental retardation, and developmental disabilities.

The efficacy and safety of topiramate in patients with intractable mixed seizures, mental retardation (MR), and developmental disabilities (DD) were investigated. Twenty patients (eight females and 12 males) aged 21-57 years old with intractable epilepsy with mixed seizures, MR [profound (five), severe (three), moderate (two), mild (eight) and borderline (two)], and DD were treated with adjunctive topiramate 25 mg per day for 1 week followed by titration to clinical response (range 50-350 mg per day). Other antiepileptic drugs (AEDs) were decreased simultaneously. Topiramate therapy was discontinued in four patients for adverse events consisting of disorientation, unsteadiness, and pneumonia (one patient); anaphylactic shock from a tuna fish allergy (one); patient choice (one); and loss to follow-up (one). Seizures improved by gt-or-equal, slanted 50% in 11 of 16 patients (69%). Two patients (13%) were seizure free, including one patient who prior to topiramate therapy was seizure free but experiencing an intolerable adverse effect during therapy with another AED. Seizure duration and/or severity decreased in seven patients (44%). An increase in alertness was observed in 11 patients (59%). Topiramate was associated with improvement in seizure severity and alertness in this series and may be useful as adjunctive therapy in patients with mixed seizures, MR, and DD.     

Effects of lamotrigine and phenytoin on the pharmacokinetics of atorvastatin in healthy volunteers

Purpose: Statins and antiepileptic drugs (AEDs) are frequently coprescribed to individuals with hypercholesterolemia and new‐onset seizures. Statins are metabolized by the cytochrome P450 (CYP) enzyme system. Interactions between statins and agents that undergo CYP metabolism are common. In this study, the effects of two commonly prescribed AEDs, lamotrigine and phenytoin, with different routes of metabolism (CYP3A4 versus glucuronic acid conjugation) on atorvastatin pharmacokinetics were evaluated. Methods: Healthy volunteers (n = 119) received atorvastatin 40 mg/day for 7 days followed by addition of lamotrigine (target 300 mg/day) or phenytoin (target ∼4 mg/kg per day) in this open‐label, single‐sequence, two‐cohort study. Serial pharmacokinetic sampling of atorvastatin was conducted on day 7 of atorvastatin dosing and day 70 of lamotrigine + atorvastatin dosing or day 28 of phenytoin + atorvastatin dosing. Main outcome measures were steady‐state area under the curve over the 24‐h dosing interval (AUC_(0–τ)) and maximum concentration (C_max) of atorvastatin and its metabolites, 2OH‐atorvastatin and 4OH‐atorvastatin, in the presence of lamotrigine or phenytoin. Key Findings: When atorvastatin was administered with lamotrigine compared with when atorvastatin was administered alone, atorvastatin AUC_(0–τ) was within bounds indicating no interaction, whereas C_max was slightly higher(14%); AUC_(0–τ) and C_max were 3% and 20% higher, respectively, for 2OH‐atorvastatin and 25% and 21% higher, respectively, for 4OH‐atorvastatin.When atorvastatin was administered with phenytoin compared with when atorvastatin was administered alone, reductions in AUC_(0–τ) and C_max were observed for atorvastatin (54% and 24%, respectively), 2OH‐atorvastatin (53% and 22%, respectively), and 4OH‐atorvastatin (44% and 52%, respectively). Significance: Pharmacokinetics of atorvastatin were not significantly affected by coadministration with lamotrigine. Phenytoin significantly reduced atorvastatin bioavailability. Consistent with the published literature, these data are consonant with the possibility that atorvastatin does not require dose adjustment when coadministered with lamotrigine at doses to 300 mg/day, whereas atorvastatin coadministered with phenytoin may require atorvastatin dose adjustment to maintain atorvastatin exposure.     

Topiramate slow dose titration: improved efficacy and tolerability

Topiramate is an effective treatment for several types of seizures. The aim of this study is to assess the efficacy and tolerability of slow topiramate dose titration as add-on therapy in childhood epilepsy. This investigation is a prospective open-label, single-center, add-on study in 22 children with a diagnosis of refractory epilepsy. Topiramate (dose 0.5-2 mg/kg/day) was titrated at 2-week intervals up to the recommended dose of 6-12 mg/kg/day. Seizure frequency rate reduction was significant, declining from 23 +/- 5.1 seizures/week (mean +/- S.E.M.) at baseline phase to 3.5 +/- 1.2 seizures/week at the end of the 16-week stabilization phase (P < 0.001). After 16 weeks of stabilization, 19 patients (86%) had more than 50% seizure reduction. Seven patients (31%) were 100% seizure-free. Two patients (9%) manifested no improvement; only one patient (5%) did not tolerate the added drug and discontinued topiramate. One patient manifested severe side effects, whereas 21 patients experienced mild to moderate side effects mostly represented by somnolence, nervousness, and anorexia with or without weight loss. We conclude that slow dose titration improves efficacy and tolerability of topiramate as add-on therapy in the treatment in refractory epilepsy.     

Efficacy and tolerability of topiramate in children younger than 2 years old

To evaluate the efficacy and tolerability of topiramate in children with epilepsy younger than 2 years of age, we retrospectively reviewed the records of patients treated at our institution between 2001 and 2003. Thirteen children ages 5 to 23 months, five boys and eight girls, were identified. Seizure types were partial (five), generalized tonic-clonic (three), myoclonic (one), and infantile spasms (four). The mean age at seizure onset was 9.7 months. Topiramate was started at a mean age of 11.4 months (4-23 months). The number of antiepileptic drugs prior to topiramate therapy ranged from zero to four. One patient had been on the ketogenic diet. Topiramate was used as monotherapy in seven children and as polytherapy in six children. Mean follow-up was 14 months. The mean dose of topiramate was 8.8 mg/kg/day (2.5-18 mg/kg/day). The degree of seizure reduction was as follows: > 75% in five (38.5%) children, 50% to 75% in three (23%) children, and 0 to 25% in five (38.5%) children. Three of four (75%) patients with infantile spasms had a > 75% reduction in seizures. Adverse effects occurred in two children, including lethargy, hyperthermia, and anorexia. In children younger than 2 years of age, for whom the antiepileptic drug armamentarium is limited, topiramate appears to be an efficacious and safe therapeutic alternative for a variety of seizure types.