Clinical comparison of extended-release divalproex versus delayed-release divalproex: pooled data analyses from nine trials

(+)-Borneol enantiomer ameliorates epileptic seizure via decreasing the excitability of glutamatergic transmission

Epilepsy is one common brain disorder, which is not well controlled by current pharmacotherapy. In this study we characterized the therapeutic potential of borneol, a plant-derived bicyclic monoterpene compound, in the treatment of epilepsy and elucidated the underlying mechanisms. The anti-seizure potency and properties of borneol were assessed in both acute and chronic mouse epilepsy models. Administration of (+)-borneol (10, 30, 100 mg/kg, i.p.) dose-dependently attenuated acute epileptic seizure in maximal-electroshock seizure (MES) and pentylenetetrazol (PTZ)-induced seizure models without obvious side-effect on motor function. Meanwhile, (+)-borneol administration retarded kindling-induced epileptogenesis and relieved fully kindled seizures. Importantly, (+)-borneol administration also showed therapeutic potential in kainic acid-induced chronic spontaneous seizure model, which was considered as a drug-resistant model. We compared the anti-seizure efficacy of 3 borneol enantiomers in the acute seizure models, and found (+)-borneol being the most satisfying one with long-term anti-seizure effect. In electrophysiological study conducted in mouse brain slices containing the subiculum region, we revealed that borneol enantiomers displayed different anti-seizure mechanisms, (+)-borneol (10 μM) markedly suppressed the high frequency burst firing of subicular neurons and decreased glutamatergic synaptic transmission. In vivo calcium fiber photometry analysis further verified that administration of (+)-borneol (100 mg/kg) inhibited the enhanced glutamatergic synaptic transmission in epilepsy mice. We conclude that (+)-borneol displays broad-spectrum anti-seizure potential in different experimental models via decreasing the glutamatergic synaptic transmission without obvious side-effect, suggesting (+)-borneol as a promising anti-seizure compound for pharmacotherapy in epilepsy.

Efficacy, Safety, and Retention Rate of Extended-Release Divalproex Versus Conventional Delayed-Release Divalproex: A Meta-Analysis of Controlled Clinical Trials

Purpose: A novel once-daily divalproex-extended release (ER) dose formulation has been developed; this formulation prolongs the therapeutic serum levels of the drug, compared with the twice-daily conventional divalproex-delayed release (DR) formulation. This study aimed to systematically examine and compare the efficacy, safety, and retention rates of the ER divalproex (VPA-ER) and conventional DR divalproex (VPA-DR) formulations.

Methods: Randomized control trials (RCTs) reporting the efficacy, adverse events (AEs), and medication compliance of ER and DR divalproex were searched in online databases, including PubMed, Embase, and Cochrane Library databases, by searching MeSH words and term words. Observational studies with potential biases were excluded. The meta-analysis was performed using Stata 16.0 software.

Findings: Thirteen RCTs, involving 1,028 participants, were included in this meta-analysis. Efficacy, AEs, and drug retention rates were the main study outcomes. According to our study, VPA-ER presented clinically significant benefits compared with the placebo in the population with bipolar disorder (BD) (39.5% versus 27.2%, p < 0.001). A similar efficacy of VPA-ER and VPA-DR in controlling seizures was observed in epilepsy patients (87.4% versus 86.5%, p = 0.769). A significantly lower incidence of AEs was reported in the VPA-ER group than in the placebo group (26.8% versus 34.8%, p = 0.003). By contrast, there was no evidence of difference in safety between VPA-ER and VPA-DR (29.4% versus 30.5%, p = 0.750). In addition, the drug retention rate was significantly lower in the VPA-ER group than in the placebo group (76.0% versus 82.7%, p = 0.020), especially in migraine patients (p = 0.022) and in patients who were treated for fewer than 4 weeks (p = 0.018).

Implications: The efficacy of VPA-ER was significantly superior to that of the placebo treatment, which provided efficacy similar to that of conventional VPA-DR. VPA-ER is well tolerated with a low rate of AEs compared to the placebo. In addition, the acceptable medicine compliance of VPA-ER was conducive to the long-term maintenance treatment of chronic diseases. Although we analyzed open labels and crossover design RCTs, large-scale multicenter studies on the efficacy and medicine compliance of new ER formulations with less AEs are required to validate our conclusion.

Update on Antiseizure Medications 2022

EDITORS NOTE

The article "Update on Antiseizure Medications 2022" by Dr Abou-Khalil was first published in the February 2016 Epilepsy issue of Continuum: Lifelong Learning in Neurology as "Antiepileptic Drugs," and at the request of the Editor-in-Chief was updated by Dr Abou-Khalil for the 2019 issue and again for this issue.

Efficacy, safety, and retention rate of extended-release divalproex versus conventional delayed-release divalproex: A protocol for systematic review and meta-analysis

BACKGROUND

A novel once-daily divalproex-extended release (VPA-ER) dose formulation has been developed, which prolongs therapeutic serum levels compared with that of twice-daily conventional divalproex-delayed release (VPA-DR). Currently, there is lack of meta-analysis focusing on drug retention rate between VPA-ER and VPA-DR. Thus, our study is the first one that aims to systematically examine and compare the efficacy, safety, and retention rate of VPA-ER and VPA-DR.

METHODS

Online databases including MEDLINE via PubMed, Cochrane Library, Embase (up to October 30, 2021) will be applied for literature screen. We will conduct meta-analysis by using Stata16.0 software.

RESULTS

This study aims to evaluate the efficacy, safety, and drug retention rate of VPA-ER versus conventional VPA-DR.

CONCLUSION

Once-daily VPA-ER may present a positive efficacy and not increase the incidence of AEs and has a higher retention rate for patients, which can be used as a substitute for conventional VPA-DR.INPLASY registration number: INPLASY2021110090(DOI: 10.37766/inplasy2021.11.0090).

Update on Antiepileptic Drugs 2019

PURPOSE OF REVIEW

This article is an update from the article on antiepileptic drug (AED) therapy published in the last Continuum issue on epilepsy and is intended to cover the vast majority of agents currently available to the neurologist in the management of patients with epilepsy. Treatment of epilepsy starts with AED monotherapy. Knowledge of the spectrum of efficacy, clinical pharmacology, and modes of use for individual AEDs is essential for optimal treatment for epilepsy. This article addresses AEDs individually, focusing on key pharmacokinetic characteristics, indications, and modes of use.

RECENT FINDINGS

Since the previous version of this article was published, three new AEDs, brivaracetam, cannabidiol, and stiripentol, have been approved by the US Food and Drug Administration (FDA), and ezogabine was removed from the market because of decreased use as a result of bluish skin pigmentation and concern over potential retinal toxicity.Older AEDs are effective but have tolerability and pharmacokinetic disadvantages. Several newer AEDs have undergone comparative trials demonstrating efficacy equal to and tolerability at least equal to or better than older AEDs as first-line therapy. The list includes lamotrigine, oxcarbazepine, levetiracetam, topiramate, zonisamide, and lacosamide. Pregabalin was found to be less effective than lamotrigine. Lacosamide, pregabalin, and eslicarbazepine have undergone successful trials of conversion to monotherapy. Other newer AEDs with a variety of mechanisms of action are suitable for adjunctive therapy. Most recently, the FDA adopted a policy that a drug's efficacy as adjunctive therapy in adults can be extrapolated to efficacy in monotherapy. In addition, efficacy in adults can be extrapolated for efficacy in children 4 years of age and older. Both extrapolations require data demonstrating that an AED has equivalent pharmacokinetics between its original approved use and its extrapolated use. In addition, the safety of the drug in pediatric patients has to be demonstrated in clinical studies that can be open label. Rational AED combinations should avoid AEDs with unfavorable pharmacokinetic interactions or pharmacodynamic interactions related to mechanism of action.

SUMMARY

Knowledge of AED pharmacokinetics, efficacy, and tolerability profiles facilitates the choice of appropriate AED therapy for patients with epilepsy.

The clinical features and functional impact of valproate-induced tremor

BACKGROUND

Tremor is a known side-effect of anticonvulsants, particularly of valproate. However, there is a dearth of information regarding detailed clinical features and functional impact of valproate-induced tremor.

METHODS

We studied a cohort of patients treated with anticonvulsants for neurological disorders, through blinded evaluations using the Clinical Rating Scale for Tremor (CRST); we compared the frequency, severity and functional impact of drug-induced tremor between patients treated with valproate and those treated with other anticonvulsants.

RESULTS

From a cohort of 218 consecutive patients, 171 were fully evaluated; 118 patients were taking valproate alone or combined with other anticonvulsants and 53 patients were taking other anticonvulsants. Mean age (±SD) at evaluation of the cohort was 32 ± 13 years, females represented 55.6% of cases. Tremor was more frequently observed in patients taking valproate particularly postural upper limb tremor: 49% vs. 15% (right-side) (P < 0.001) and 48.3% vs. 13.2% (left-side), (P < 0.001); had a higher total CRST score: 12.14 vs. 3.06 (P < 0.001), and required more frequently treatment for drug-induced tremor: 23.7% vs. 5.6% (P=0.005) compared with patients taking other anticonvulsants. Among 118 patients taking valproate, women had a higher total CRST score compared with men: 14.54 ± 14.9 vs. 9.56 ± 9.55 (P=0.034). A weak correlation between the total CRST score, dose per Kg of valproate and serum levels of valproate were observed.

CONCLUSIONS

Tremor is frequently observed in patients taking valproate and is severe enough to require treatment in about 24% of cases.

Comparative Absorption Profiles of Divalproex Sodium Delayed-Release Versus Extended-Release Tablets—Clinical Implications

Background:

The distinct absorption characteristics of the conventional enteric-coated, delayed-release (DR) and the novel extended-release (ER) divalproex sodium formulations are not well recognized.

Objective:

To quantitatively and qualitatively differentiate the absorption characteristics of divalproex-DR and -ER formulations.

Methods:

Healthy volunteers (N = 28) received single 1000 mg doses of divalproex-DR and divalproex-ER tablets in a crossover fashion. Noncompartmental and compartmental analyses were used to estimate valproic acid (VPA) pharmacokinetics from the plasma concentration–time profiles determined from intensive blood sampling over 48 hours.

Results:

VPA was not absorbed from divalproex-DR in the first 2 hours (absorption lag-time) after dosing. After VPA release in the intestine, approximately 63% of the dose was absorbed in less than 1 hour, that is, 2.9 hours (mean absorption time) from dosing. Maximum concentration (Cmax) was achieved approximately 4 hours after dosing. VPA absorption was complete (~93% of dose) within 3 absorption half-lives (~4.5 h) post-absorption lag-time, that is, 6–7 hours from dosing. In contrast, VPA absorption from divalproex-ER starts immediately after administration, initially at a modest rate, followed by slow and extended absorption at a constant rate for more than 20 hours; VPA concentrations at 1 and 2 hours were 28% and 40% of Cmax. Approximately 53% of the dose was absorbed within 12 hours (mean absorption time); complete absorption occurred over more than 20 hours without any dose dumping.

Conclusions:

When antihypertensive treatment options are clinically equivalent, prescribers may first consider using a verapamil SR–based strategy, especially in patients with CAD who have no history of depression. VPA absorption from enteric-coated divalproex-DR is rapid following a lag-time of approximately 2 hours and is complete within 6–7 hours of dosing. In contrast, VPA absorption from divalproex-ER starts immediately after administration, but occurs at a slow, approximately constant rate over more than 20 hours.

Management of adverse effects of mood stabilizers

Mood stabilizers such as lithium and anticonvulsants are still standard-of-care for the acute and long-term treatment of bipolar disorder (BD). This systematic review aimed to assess the prevalence of their adverse effects (AEs) and to provide recommendations on their clinical management. We performed a systematic research for studies reporting the prevalence of AEs with lithium, valproate, lamotrigine, and carbamazepine/oxcarbazepine. Management recommendations were then developed. Mood stabilizers have different tolerability profiles and are eventually associated to cognitive, dermatological, endocrine, gastrointestinal, immunological, metabolic, nephrogenic, neurologic, sexual, and teratogenic AEs. Most of those can be transient or dose-related and can be managed by optimizing drug doses to the lowest effective dose. Some rare AEs can be serious and potentially lethal, and require abrupt discontinuation of medication. Integrated medical attention is warranted for complex somatic AEs. Functional remediation and psychoeducation may help to promote awareness on BD and better medication management.

Conversion from immediate-release to extended-release lamotrigine improves seizure control

BACKGROUND

Immediate release lamotrigine (LTG-IR) dosing can be limited by peak toxicity. It is thought that peak levels are responsible for some adverse effects such as dizziness, blurred vision, double vision and unsteadiness. At the same time, trough levels may be associated with reduced seizure threshold. The use of extended release lamotrigine (LTG-XR) to replace LTG-IR will be associated with less fluctuation in drug levels-lower peak levels may reduce adverse effects and higher trough levels may improve seizure control. This hypothesis was tested by analyzing seizure control and adverse effects before and after conversion from LTG-IR to LTG-XR in patients who underwent such conversion in 2009-2011.

METHODS

We searched our patient database to identify patients converted from LTG-IR to LTG-XR for persistent seizures or adverse effects from August 2009 until December 31, 2011. We included only patients who took LTG-IR and LTG-XR for at least 6 months each. We excluded patients with nonepileptic seizures, progressive cause of epilepsy, or not keeping a seizure record. We collected the following parameters: age at conversion, LTG-IR dose and dosing schedule, duration on that dose, LTG-XR dose and dosing schedule, LTG serum level before and after conversion, duration of LTG-XR treatment, seizure frequency before and after conversion, and change in adverse experience profile. We also recorded baseline AEDs and any AED change during the course of the analysis.

RESULTS

Fifty five patients (26 female) satisfied the inclusion/exclusion criteria. Their mean age was 45 years (range 23 to 86). Ten were on LTG-IR monotherapy, 24 took LTG-IR plus one other AED, most commonly levetiracetam, and the remaining 21 took LTG-IR plus at least 2 other AEDs. The mean LTG-IR dose was 544 mg/day (range 150-1100 mg/day). The mean LTG-IR serum level was 11.6 (available in 53 patients-range 4.6-21 mcg/ml). Twenty six patients were converted to the same dose and one patient took a mixture of LTG-XR and LTG-IR at the same total daily dose, while 21 had their dose slightly increased and 7 had their dose slightly decreased due to adverse effects. The mean serum level after conversion was 11.8 (available in 49 patients-range 2.6-21.2 mcg/ml). As a result of the conversion, 26 patients (47%) experienced >50% reduction in seizure frequency. There was a 46% median reduction in seizure frequency overall. Seven patients reported improvement in adverse effects.

CONCLUSION

A conversion from LTG-IR to LTG-XR can help improve seizure control in some individuals with drug-resistant epilepsy, in addition to improving tolerability. While it is indicated in individuals experiencing peak adverse effects, it should also be considered in patients who have received incomplete seizure control from LTG-IR.

USL255 extended-release topiramate: dose-proportional pharmacokinetics and tolerability in healthy volunteers

Objective

Evaluate the pharmacokinetics (PK), safety, and tolerability of single doses of once-daily USL255, Qudexy XR (topiramate) extended-release capsules, over a wide dosing range.

Methods

Two single-dose, phase I studies in healthy adults were used to evaluate the PK profile and maximum tolerated dose (MTD) of USL255 from 25–1,400 mg. Standard PK parameters assessed included area under the plasma concentration-time curve (AUC) and maximum plasma concentration (C_max). Dose proportionality, linearity, and intersubject and intrasubject variability (coefficient of variation [%CV]) of AUC and C_max were evaluated. Investigator-reported adverse events (AEs) were obtained throughout the studies.

Results

After the initial increase in plasma concentration levels immediately following administration of USL255 25–1,400 mg, plasma topiramate concentration-time profiles were flat up to 24 h after dosing. AUC was dose proportional from 25–1,400 mg, and C_max was dose proportional from 50–1,400 mg; both AUC and C_max were linear across the entire dose range. Low intersubject and intrasubject %CV values were observed for AUC_0−t, AUC_0−∞, and C_max (intersubject %CV: 20.2, 19.6, and 22.4%, respectively; intrasubject %CV of dose-normalized mean values: 10.8, 8.2, and 13.2%, respectively). USL255 was generally safe and well tolerated with MTD established at 1,200 mg.

Significance

These results demonstrate that USL255 provides consistent plasma topiramate exposure across an extended-dosing interval and predictable plasma topiramate concentrations over a wide dosing range. Overall, the favorable safety profile and consistency of exposure suggest once-daily USL255 can be a useful treatment option for patients with epilepsy.

KOMET: an unblinded, randomised, two parallel-group, stratified trial comparing the effectiveness of levetiracetam with controlled-release carbamazepine and extended-release sodium valproate as monotherapy in patients with newly diagnosed epilepsy

OBJECTIVE

To compare the effectiveness of levetiracetam (LEV) with extended-release sodium valproate (VPA-ER) and controlled-release carbamazepine (CBZ-CR) as monotherapy in patients with newly diagnosed epilepsy.

METHODS

This unblinded, randomised, 52-week superiority trial (NCT00175903) recruited patients (≥16 years of age) with ≥2 unprovoked seizures in the previous 2 years and ≥1 in the previous 6 months. The physician chose VPA or CBZ as preferred standard treatment; each patient was randomised to standard treatment or LEV. The primary outcome was time to treatment withdrawal (LEV vs standard antiepileptic drugs (AEDs)). Analyses also compared LEV with VPA-ER, and LEV with CBZ-CR.

FINDINGS

1688 patients (mean age 41 years; 44% female) were randomised to LEV (n=841) or standard AEDs (n=847). Time to treatment withdrawal was not significantly different between LEV and standard AEDs: HR (95% CI) 0.90 (0.74 to 1.08). Time to treatment withdrawal (HR (95% CI)) was 1.02 (0.74 to 1.41) for LEV/VPA-ER and 0.84 (0.66 to 1.07) for LEV/CBZ-CR. Time to first seizure (HR, 95% CI) was significantly longer for standard AEDs, 1.20 (1.03 to 1.39), being 1.19 (0.93 to 1.54) for LEV/VPA-ER and 1.20 (0.99 to 1.46) for LEV/CBZ-CR. Estimated 12-month seizure freedom rates from randomisation: 58.7% LEV versus 64.5% VPA-ER; 50.5% LEV versus 56.7% CBZ-CR. Similar proportions of patients within each stratum reported at least one adverse event: 66.1% LEV versus 62.0% VPA-ER; 73.4% LEV versus 72.5% CBZ-CR.

CONCLUSIONS

LEV monotherapy was not superior to standard AEDs for the global outcome, namely time to treatment withdrawal, in patients with newly diagnosed focal or generalised seizures.

The long-term safety of antiepileptic drugs

Antiepileptic drugs (AEDs) are used by millions of people worldwide for the treatment of epilepsy, as well as in many other neurological and psychiatric conditions. They are frequently associated with adverse effects (AEs), which have an impact on the tolerability and success of treatment. Half the people who develop intolerable AEs discontinue treatment early on after initiation, while the majority of people will continue to be exposed to their effects for long periods of time. The long-term safety of AEDs reflects their potential for chronic, cumulative dose effects; rare, but potentially serious late idiosyncratic effects; late, dose-related effects; and delayed, teratogenic or neurodevelopmental effects. These AEs can affect every body system and are usually insidious. With the exception of delayed effects, most other late or chronic AEs are reversible. To date, there is no clear evidence of a carcinogenic effect of AEDs in humans. While physicians are aware of the long-term AEs of old AEDs (the traditional liver enzyme-inducing AEDs and valproate), information about AEs of new AEDs (such as lamotrigine, levetiracetam, oxcarbazepine, topiramate or zonisamide), particularly of their teratogenic effects, has emerged over the years. Sporadic publications have raised issues about AEs of the newer AEDs eslicarbazepine, retigabine, rufinamide, lacosamide and perampanel but their long-term safety profiles may take years to be fully appreciated. Physicians should not only be aware of the late and chronic AEs of AEDs but should systematically enquire and screen for these according to the individual AED AE profile. Care should be taken for individuals with comorbid conditions that may render them more susceptible to specific AEs. Prevention and appropriate management of long-term AED AEs is expected to improve adherence to treatment, quality of life and control of epilepsy.

Extended-release antiepileptic drugs: a comparison of pharmacokinetic parameters relative to original immediate-release formulations

Many antiepileptic drugs (AEDs) have short half-lives with large fluctuations in peak-to-trough plasma concentrations. Consequences of these pharmacokinetic (PK) properties may include adverse events (AEs) and breakthrough seizures, potentially leading to poor adherence. To address these challenges, newer formulations of these AEDs have been developed using unique extended-release (ER) technologies. These technologies extend the dosing interval such that dosing frequency can be minimized, which may improve patient adherence. Available ER formulations have the potential to minimize the spikes in maximum plasma concentrations (C(max) ) at steady-state that often contribute to AEs during treatment with immediate-release (IR) products. In so doing, tolerability advantages may lead to increased AED effectiveness by improving adherence and allowing higher doses if clinically indicated. Direct PK comparison studies of IR and ER formulations (e.g., carbamazepine, divalproate sodium, lamotrigine, oxcarbazepine, levetiracetam, and phenytoin) have found that dose-normalized ER formulations may or may not be bioequivalent to their IR counterparts, but most ER formulations have a lower fluctuation index ([C(max) -C(min) ]/C(avg) ) compared with the IR versions. This results in flatter concentration-time plots. Not all ER preparations improve the various PK parameters to the same extent, and PK nuances may impact the effectiveness, tolerability, and adherence rates of various ER formulations.

Changes in body weight and psychotropic drugs: a systematic synthesis of the literature

INTRODUCTION

Psychotropic medication use is associated with weight gain. While there are studies and reviews comparing weight gain for psychotropics within some classes, clinicians frequently use drugs from different classes to treat psychiatric disorders.

OBJECTIVE

To undertake a systematic review of all classes of psychotropics to provide an all encompassing evidence-based tool that would allow clinicians to determine the risks of weight gain in making both intra-class and interclass choices of psychotropics.

METHODOLOGY AND RESULTS

We developed a novel hierarchical search strategy that made use of systematic reviews that were already available. When such evidence was not available we went on to evaluate randomly controlled trials, followed by cohort and other clinical trials, narrative reviews, and, where necessary, clinical opinion and anecdotal evidence. The data from the publication with the highest level of evidence based on our hierarchical classification was presented. Recommendations from an expert panel supplemented the evidence used to rank these drugs within their respective classes. Approximately 9500 articles were identified in our literature search of which 666 citations were retrieved. We were able to rank most of the psychotropics based on the available evidence and recommendations from subject matter experts. There were few discrepancies between published evidence and the expert panel in ranking these drugs.

CONCLUSION

Potential for weight gain is an important consideration in choice of any psychotropic. This tool will help clinicians select psychotropics on a case-by-case basis in order to minimize the impact of weight gain when making both intra-class and interclass choices.

Pharmacotherapeutics of epilepsy: use of lamotrigine and expectations for lamotrigine extended release

The goal in managing patients with epilepsy is complete seizure freedom. Pharmacotherapeutic management of epilepsy is complicated by multiple syndromes, inter-individual differences in drug sensitivities, inter-individual differences in drug disposition, and drug interactions. Most anti-epileptic drugs (AEDs) have a therapeutic window with only a 2- to 3-fold concentration range. Extended release formulations offer advantages over their immediate release counter parts with less fluctuation in the serum concentration vs time curve and improved compliance. However, missed doses are more likely to result in prolonged “sub-therapeutic serum concentrations”. Best clinical outcome may sometimes require twice daily dosing of extended release formulations even though approved for once daily dosing, as this optimally balances pharmacokinetics against compliance. Lamotrigine (LTG) is a broad spectrum AED with efficacy in partial and generalized epilepsy syndromes and good tolerability. Its metabolism is affected by co-medications which may be inducing, neutral or inhibiting of hepatic glucuronidation. Furthermore, though the average half-life in monotherapy is about 24 hours, there is a large inter-individual variation that may, including the extremes, approach a range of 10-fold. LTG-XR is expected to decrease fluctuation of serum concentration in the presence of hepatic inducing or neutral drugs. However, optimal clinical benefit in some patients may require twice daily dosing when metabolism is rapid.

Once-daily dosing is appropriate for extended-release divalproex over a wide dose range, but not for enteric-coated, delayed-release divalproex: evidence via computer simulations and implications for epilepsy therapy

Divalproex sodium extended-release (divalproex-ER), administered once-daily, maintains plasma valproic acid (VPA) concentrations for 24h, whereas enteric-coated, delayed-release divalproex sodium (divalproex) requires multiple-daily doses to do the same. We hypothesize that a once-daily divalproex regimen should not be administered to epilepsy patients requiring high total daily doses, e.g., 35.6-56 mg/kg/day, due to the potential for high (>125 mg/L) maximum VPA concentrations (C(max)). We examined the impact of once-daily dosing, divalproex vs. divalproex-ER, on steady-state plasma VPA concentration-time profiles at commonly used doses in monotherapy (uninduced) and polytherapy (hepatic enzyme-induced) virtual adult patients. Only the 1125 mg once-daily divalproex dose had mean C(max)<100mg/L; >or=2000 mg produced mean C(max)>or=125 mg/L. Mean divalproex C(min) was approximately 50 mg/L at two of four doses tested, whereas mean ER C(min) was >73 mg/L at all doses tested. Once-daily divalproex peak-trough fluctuation was 4.4-6.2-fold greater than once-daily divalproex-ER. We predict that excursions beyond the conventional recommended VPA plasma concentration range will commonly occur with high total mg daily doses (>or=2000 mg) of enteric-coated divalproex, if dosed once-daily, potentially producing clinical toxicity. This divalproex formulation should not be dosed once-daily at high total mg daily doses due to this risk. Divalproex-ER is the appropriate formulation for administration on a once-daily basis, especially if large total mg/day doses are required for the control of seizure activity.

Effect of valproic acid on body weight, food intake, physical activity and hormones: results of a randomized controlled trial

The objective of this study was to identify mechanisms through which valproic acid (VPA) causes weight gain. Healthy participants (N = 52) were randomized to VPA or placebo in a double-blind study. Energy intake (EI) was measured in the laboratory at lunch and dinner, and physical activity (PA) was measured with accelerometry. Glucose levels and hormones [Peptide YY(3-36), glucagon-like peptide-1 (GLP-1), leptin, ghrelin, insulin] that regulate EI were measured. Assessments occurred at baseline and week 3. Change from baseline was evaluated with mixed models (alpha = 0.05). Weight significantly increased in the VPA group (+0.49 kg), but not the placebo group. The VPA group increased fast food fats cravings and decreased glucose levels compared with placebo. Change in weight, EI and PA did not differ by group. Within group analyses indicated that the VPA group increased PA, hunger, binge eating, depression and GLP-1. VPA-associated weight gain is not likely due to changes in PA or the gut hormones studied. Although EI did not increase when measured after 3 weeks of treatment, VPA decreased glucose levels and increased motivation to eat; hence, EI might have increased in the short-term. Research testing VPA on short-term (1 week) EI, metabolism, and substrate partitioning is warranted.

Weight gain in children treated with valproate

Weight gain in children due to valproate is a major concern in the treatment of epilepsy. Previous studies have yielded conflicting results both as to how common this problem is in children and as to whether there are clinical predictors of weight gain. The authors perform a chart review of 94 pediatric patients treated with valproate to investigate weight gain and potential predictors. The slope of the regression line for the body mass index z scores for each patient at each available visit was calculated, (Deltaz-score). Relationships between Deltaz scores and predictors of interest were assessed via univariate analyses. Twenty-three of 94 patients had Deltaz score >0.25 SD/year. Twelve of 94 patients had Deltaz score >0.5 SD/year. Pediatric participants appear to be less prone to weight gain on valproate than adults. A negative correlation was found between duration on treatment and Deltaz score. No other significant correlations were found between potential clinical predictors and Deltaz score.

Cost analysis of divalproex sodium extended-release compared to valproic acid in the treatment of bipolar disorder

OBJECTIVES

To analyze, from a payer perspective, the net pharmaceutical and medical costs of prescribing divalproex sodium extended-release (DVPX-ER) versus valproic acid (VPA) in patients with bipolar disorder.

METHODS

The study used a decision analytic framework to compare the total costs associated with DVPX-ER relative to VPA in the treatment of bipolar disease. The decision model incorporated two primary outcomes: GI side effects and treatment success. Levels of health service utilization and probability values were obtained from an expert panel comprised of 15 psychiatrists. Unit costs were obtained from an academic medical center. Two-way sensitivity analysis and a Monte Carlo simulation were conducted to examine the stability of the results.

RESULTS

The average probability of GI side effects associated with VPA and DVPX-ER estimated by the expert panel was 0.36 and 0.10 respectively. The average probability of treatment success for VPA and DVPX-ER was estimated to be 0.45 and 0.58 respectively. In the base case analysis, the expected total cost per patient was $34 208.84 and $25 336.13 for VPA and DVPX-ER respectively, a difference (incremental cost) of -$8188.87. Probabilistic sensitivity analysis using Monte Carlo simulation indicated a negative incremental cost of using DVPX-ER relative to VPA in a majority (approximately 70%) of cases.

CONCLUSIONS

The results from this decision analysis, based on probabilities of major events and associated utilization from an expert panel, suggest that divalproex sodium extended-release results in lower total costs than valproic acid in the treatment of bipolar disorder. Limitations of this study primarily involved the sources of data used in the model, including that derived from expert opinion.

Extended-release formulations in epilepsy

In the past years, the extended-release antiepileptic drug formulations have been developed and then approved for the treatment of many types of epilepsy. Among these extended-release formulations of antiepileptic drugs, the main drugs are valproic acid, carbamazepine, and phenytoin. This review analyzes the chemical and structural characteristics of the extended-release formulations of these 3 antiepileptic drugs, analyzing their bioequivalence and the studies about their clinical use. The results of these studies are encouraging and suggest a good tolerability and efficacy of these extended-release formulations, although larger studies are needed.

Clinical Utility of a Continuous Intravenous Infusion of Valproic Acid in Pediatric Patients

STUDY OBJECTIVE

To describe the dose-concentration relationship of a continuous intravenous infusion of valproic acid (VPA) in pediatric patients when a dosing protocol is used.

DESIGN

Retrospective and concurrent chart review.

SETTING

Tertiary care, 473-bed, academic medical center with a 120-bed, dedicated children's hospital.

PATIENTS

Twenty-six pediatric patients (< 18 yrs old) who received VPA according to the protocol for continuous intravenous infusions between January 1, 2004, and March 31, 2006, identified by using a pharmacy order-entry system.

MEASUREMENTS AND MAIN RESULTS

Patient demographics, VPA treatment regimens, clinical responses, and safety data were recorded and analyzed. Median patient age was 8.5 years (range 1.4-16 yrs). Approximately two thirds received VPA for seizures, and one third for migraines. Patients were given a mean +/- SD VPA loading dose of 28.5 +/- 5.2 mg/kg followed by a continuous infusion rate of 1 +/- 0.2 mg/kg/hour. Mean +/- SD serum concentration measured 4.5 +/- 1.6 hours after the loading dose was 83.3 +/- 22.8 microg/ml. Steady-state concentration at 23.3 +/- 3.0 hours after the start of the continuous infusion was 80.0 +/- 26.0 microg/ml. Postload and steady-state serum concentrations were within the target concentration of 50-100 microg/ml in 77% and 69% of patients, respectively. On further analysis, when the target range was expanded to 50-125 microg/ml (125 microg/ml was deemed acceptable if no adverse effects were noted), 89% and 92% of patients, respectively, had postload and steady-state VPA serum concentrations within this range. The response rate was excellent, with nearly 85% of patients achieving a complete or partial response to therapy. Adverse effects were generally mild and uncommon.

CONCLUSIONS

The continuous-infusion protocol permitted rapid intravenous loading of VPA in pediatric patients while minimizing adverse events and achieving concentrations in the upper region of the therapeutic range.

Progress report on new antiepileptic drugs: a summary of the Eigth Eilat Conference (EILAT VIII)

The Eigth Eilat Conference on New Antiepileptic Drugs (AEDs)-EILAT VII, took place in Sitges, Barcelona from the 10th to 14th September, 2006. Basic scientists, clinical pharmacologists and neurologists from 24 countries attended the conference, whose main themes included a focus on status epilepticus (epidemiology, current and future treatments), evidence-based treatment guidelines and the potential of neurostimulation in refractory epilepsy. Consistent with previous formats of this conference, the central part of the conference was devoted to a review of AEDs in development, as well as updates on marketed AEDs introduced since 1989. This article summarizes the information presented on drugs in development, including brivaracetam, eslicarbazepine acetate (BIA-2-093), fluorofelbamate, ganaxolone, huperzine, lacosamide, retigabine, rufinamide, seletracetam, stiripentol, talampanel, valrocemide, JZP-4, NS1209, PID and RWJ-333369. Updates on felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine and new extended release oxcarbazepine formulations, pregabalin, tiagabine, topiramate, vigabatrin, zonisamide and new extended release valproic acid formulations, and the antiepileptic vagal stimulator device are also presented.

Does It Really Matter When a Blood Sample for Valproic Acid Concentration is Taken Following Once-Daily Administration of Divalproex-ER?

Divalproex sodium extended-release (divalproex-ER) is a novel formulation intended for once-daily oral administration, either morning or evening. Questions have risen concerning the optimal time for obtaining a blood sample for valproic acid (VPA) concentration in relation to the dose. Trough sampling is easily achieved just before a morning daily dose, but the best time to sample after an evening daily dose is unclear, because collecting a blood sample 21 to 24 hours later may be limited by the operational hours of the laboratory. This investigation provides practical guidance regarding blood sample timing. Steady-state plasma VPA concentration-time profiles from 5 published divalproex-ER studies (healthy subjects and epilepsy patients) were analyzed. The concentration-time profile for each subject/patient was expressed as a percentage of his/her trough concentration and summary statistics computed. Typically, when taking divalproex-ER once daily in the morning, a blood sample collected 21 to 24 hours later is expected to have a concentration within 3% of the trough value. Conversely, for divalproex-ER dosed once-daily in the evening, for example 8 PM, a blood draw 12 to 15 hours later (ie, 8 to 11 AM) will give a plasma VPA concentration value that is 18% to 25% higher, on average, than the trough value. However, waiting longer, (for example 18 to 21 hours, ie 2 to 5 PM) will result in concentration values that are merely 3% to 13% higher than trough values, which may provide acceptable information for monitoring purposes. The greatest deviation from trough VPA concentration occurs around the peak, that is 3 to 15 hours after a once-daily divalproex-ER dose; sampling during this time period is recommended only if a clinical need exists to test for a higher VPA concentration. Despite the apparent smoothness of the VPA concentration-time profile after a once-daily divalproex-ER dose, the timing of the blood sample does matter and impacts the proper interpretation of the VPA concentration.

Conversion from delayed-release sodium valproate to extended-release sodium valproate: initial results and long-term follow-up

OBJECTIVE

The goal of our study was to evaluate clinical and serum valproic acid concentration changes in patients following overnight conversion from delayed-release sodium valproate (VPA-DR) to the same daily dosage of extended-release sodium valproate (VPA-ER).

METHODS

Epilepsy patients on VPA-DR were offered the chance to convert to VPA-ER. Thirty patients were converted to twice-daily dosing and 11 were converted to once-daily dosing. Trough levels of valproic acid were measured prior to the change and 2 weeks after conversion. Short-term and long-term clinical data were evaluated.

RESULTS

Patients successfully converted from VPA DR to VPA-ER. No significant difference in percentage change in serum trough valproic acid level was observed when comparing dosing frequency of VPA-DR, total daily dosage of VPA, conversion to once-daily versus twice-daily VPA-ER, or presence of enzyme-inducing agents. Mean seizure count per month prior to conversion was 3.35 versus 3.29 following conversion. Improvements in tremor, weight gain, and nausea/vomiting were noted.

CONCLUSIONS

Overnight conversion to VPA-ER was well tolerated by all patients. Long-term results were favorable, with 77.5% of patients remaining on drug. Seizure counts and adverse events remained the same or were improved in both short-term and long-term evaluations. Dosing of VPA-ER either once-daily or twice-daily is acceptable.

Every-12-hour administration of extended-release divalproex in patients with epilepsy: impact on plasma valproic acid concentrations

Extended-release divalproex sodium (divalproex-ER) biopharmaceutics after every-12-hour (q12h) administration was compared with that of once-daily divalproex-ER and conventional divalproex given every 6 hours (q6h) in a multiple-dose (14-day), randomized, three-period crossover design study in 24 patients with epilepsy concomitantly receiving enzyme-inducing antiepileptic medication(s). Plasma valproic acid (VPA) minimum concentration (Cmin) for divalproex-ER q12h was higher than the once-daily divalproex-ER Cmin (P=0.043). Once-daily divalproex-ER Cmin values were not different from those for divalproex q6h, suggesting that adequate trough steady-state concentrations are maintained with once daily dosing, despite enzyme-inducing comedication. The degree of peak-trough fluctuation (DFL, calculated as (Cmax-Cmin)/Cavg) in VPA concentration was less with both q12h (35.2% less) and once-daily (16.9% less) divalproex-ER regimens compared with q6h divalproex (P0.024). The DFL for divalproex-ER dosed as a q12h regimen was 22% less than that for once-daily divalproex-ER (P=0.02). The DFL in VPA concentration with divalproex-ER can be minimized with once-daily administration and more so with q12h administration, compared with conventional enteric-coated divalproex taken q6h.