Extended-release formulations: simplifying strategies in the management of antiepileptic drug therapy

Oral linezolid compared with benzathine penicillin G for treatment of early syphilis in adults (Trep-AB Study) in Spain: a prospective, open-label, non-inferiority, randomised controlled trial

BACKGROUND

Management of syphilis, a sexually transmitted infection (STI) with increasing incidence, is challenged by drug shortages, scarcity of randomised trial data, an absence of non-penicillin alternatives for pregnant women with penicillin allergy (other than desensitisation), extended parenteral administration for neurosyphilis and congenital syphilis, and macrolide resistance. Linezolid was shown to be active against Treponema pallidum, the causative agent of syphilis, in vitro and in the rabbit model. We aimed to assess the efficacy of linezolid for treating early syphilis in adults compared with the standard of care benzathine penicillin G (BPG).

METHODS

We did a multicentre, open-label, non-inferiority, randomised controlled trial to assess the efficacy of linezolid for treating early syphilis compared with BPG. We recruited participants with serological or molecular confirmation of syphilis (either primary, secondary, or early latent) at one STI unit in a public hospital and two STI community clinics in Catalonia (Spain). Participants were randomly allocated in a 1:1 ratio using a computer-generated block randomisation list with six participants per block, to receive either oral linezolid (600 mg once per day for 5 days) or intramuscular BPG (single dose of 2·4 million international units) and were assessed for signs and symptoms (once per week until week 6 and at week 12, week 24, and week 48) and reagin titres of non-treponemal antibodies (week 12, week 24, and week 48). The primary endpoint was treatment response, assessed using a composite endpoint that included clinical response, serological response, and absence of relapse. Clinical response was assessed at 2 weeks for primary syphilis and at 6 weeks for secondary syphilis following treatment initiation. Serological cure was defined as a four-fold decline in rapid plasma reagin titre or seroreversion at any of the 12-week, 24-week, or 48-week timepoints. The absence of relapse was defined as the presence of different molecular sequence types of T pallidum in recurrent syphilis. Non-inferiority was shown if the lower limit of the two-sided 95% CI for the difference in rates of treatment response was higher than -10%. The primary analysis was done in the per-protocol population. The trial is registered at ClinicalTrials.gov (NCT05069974) and was stopped for futility after interim analysis.

FINDINGS

Between Oct 20, 2021, and Sept 15, 2022, 62 patients were assessed for eligibility, and 59 were randomly assigned to linezolid (n=29) or BPG (n=30). In the per-protocol population, after 48 weeks' follow-up, 19 (70%) of 27 participants (95% CI 49·8 to 86·2) in the linezolid group had responded to treatment and 28 (100%) of 28 participants (87·7 to 100·0) in the BPG group (treatment difference -29·6, 95% CI -50·5 to -8·8), which did not meet the non-inferiority criterion. The number of drug-related adverse events (all mild or moderate) was similar in both treatment groups (five [17%] of 29, 95% CI 5·8 to 35·8 in the linezolid group vs five [17%] of 30, 5·6 to 34·7, in the BPG group). No serious adverse events were reported during follow-up.

INTERPRETATION

The efficacy of linezolid at a daily dose of 600 mg for 5 days did not meet the non-inferiority criteria compared with BPG and, as a result, this treatment regimen should not be used to treat patients with early syphilis.

FUNDING

European Research Council and Fondo de Investigaciones Sanitarias.

Interictal epileptiform discharges contribute to word-finding difficulty in epilepsy through multiple cognitive mechanisms

OBJECTIVE

Cognitive impairment often impacts quality of life in epilepsy even if seizures are controlled. Word-finding difficulty is particularly prevalent and often attributed to etiological (static, baseline) circuit alterations. We sought to determine whether interictal discharges convey significant superimposed contributions to word-finding difficulty in patients, and if so, through which cognitive mechanism(s).

METHODS

Twenty-three patients undergoing intracranial monitoring for drug-resistant epilepsy participated in multiple tasks involving word production (auditory naming, short-term verbal free recall, repetition) to probe word-finding difficulty across different cognitive domains. We compared behavioral performance between trials with versus without interictal discharges across six major brain areas and adjusted for intersubject differences using mixed-effects models. We also evaluated for subjective word-finding difficulties through retrospective chart review.

RESULTS

Subjective word-finding difficulty was reported by the majority (79%) of studied patients preoperatively. During intracranial recordings, interictal epileptiform discharges (IEDs) in the medial temporal lobe were associated with long-term lexicosemantic memory impairments as indexed by auditory naming (p = .009), in addition to their established impact on short-term verbal memory as indexed by free recall (p = .004). Interictal discharges involving the lateral temporal cortex and lateral frontal cortex were associated with delayed reaction time in the auditory naming task (p = .016 and p = .018), as well as phonological working memory impairments as indexed by repetition reaction time (p = .002). Effects of IEDs across anatomical regions were strongly dependent on their precise timing within the task.

SIGNIFICANCE

IEDs appear to act through multiple cognitive mechanisms to form a convergent basis for the debilitating clinical word-finding difficulty reported by patients with epilepsy. This was particularly notable for medial temporal spikes, which are quite common in adult focal epilepsy. In parallel with the treatment of seizures, the modulation of interictal discharges through emerging pharmacological means and neurostimulation approaches may be an opportunity to help address devastating memory and language impairments in epilepsy.

Neural excitatory rebound induced by valproic acid may predict its inadequate control of seizures

Background

Valproic acid (VPA) represents one of the most efficient antiseizure medications (ASMs) for both general and focal seizures, but some patients may have inadequate control by VPA monotherapy. In this study, we aimed to verify the hypothesis that excitatory dynamic rebound induced by inhibitory power may contribute to the ineffectiveness of VPA therapy and become a predictor of post-operative inadequate control of seizures.

Methods

Awake craniotomy surgeries were performed in 16 patients with intro-operative high-density electrocorticogram (ECoG) recording. The relationship between seizure control and the excitatory rebound was further determined by diagnostic test and univariate analysis. Thereafter, kanic acid (KA)-induced epileptic mouse model was used to confirm that its behavior and neural activity would be controlled by VPA. Finally, a computational simulation model was established to verify the hypothesis.

Findings

Inadequate control of seizures by VPA monotherapy and post-operative status epilepticus are closely related to a significant excitatory rebound after VPA injection (rebound electrodes≧5/64, p = 0.008), together with increased synchronization of the local field potential (LFP). In addition, the neural activity in the model mice showed a significant rebound on spike firing (53/77 units, 68.83%). The LFP increased the power spectral density in multiple wavebands after VPA injection in animal experiments (p < 0.001). Computational simulation experiments revealed that inhibitory power-induced excitatory rebound is an intrinsic feature in the neural network.

Interpretation

Despite the limitations, we provide evidence that inadequate control of seizures by VPA monotherapy could be associated with neural excitatory rebounds, which were predicted by intraoperative ECoG analysis. Combined with the evidence from computational models and animal experiments, our findings suggested that ineffective ASMs may be because of the excitatory rebound, which is mediated by increased inhibitory power.

Funding

This work was supported by National Natural Science Foundation of China (62127810, 81970418), Shanghai Municipal Science and Technology Major Project (2018SHZDZX03) and ZJLab; Science and Technology Commission of Shanghai Municipality (18JC1410403, 19411969000, 19ZR1477700, 20Z11900100); MOE Frontiers Center for Brain Science; Shanghai Key Laboratory of Health Identification and Assessment (21DZ2271000); Shanghai Shenkang (SHDC2020CR3073B).

Preparation and evaluation of bilayer-core osmotic pump tablets contained topiramate

Topiramate (TPM) was an antiepileptic agent commonly used in clinical. Studies showed that an oral preparation of TPM with extended-release manner could bring some benefits for epileptics. In this paper, controlled release push-pull osmotic pump (PPOP) tablets of sparingly water-soluble TPM were successfully prepared. This bi-layer tablet core mainly consisted of sodium chloride as osmotic promoting agent and polyethylene oxide as suspending and pushing agents. The influences of osmotic agents, pushing agents and the compositions of coating membrane on TPM release profiles were evaluated. An optimal formulation of TPM-PPOP was obtained through single-factor experiments. In vitro release tests showed that the optimum formulation could release TPM at an approximate zero-order rate up to 8 h. Pharmacokinetic behaviors of TPM-PPOP tablets were evaluated and compared with the immediate release capsules after an oral single dose in beagle dogs. Pharmacokinetics results demonstrated that the TPM-PPOP tablet was able to provide a prolonged release of TPM with longer tmax and mean residence time. Lower fluctuations of drug plasma levels could also be achieved with TPM-PPOP tablets. These results suggested that sparely water-soluble drugs as TPM can be designed to PPOP for efficacy and safety use.

Designing Drug Regimens that Mitigate Nonadherence

Medication adherence is a well-known problem for pharmaceutical treatment of chronic diseases. Understanding how nonadherence affects treatment efficacy is made difficult by the ethics of clinical trials that force patients to skip doses of the medication being tested, the unpredictable timing of missed doses by actual patients, and the many competing variables that can either mitigate or magnify the deleterious effects of nonadherence, such as pharmacokinetic absorption and elimination rates, dosing intervals, dose sizes, and adherence rates. In this paper, we formulate and analyze a mathematical model of the drug concentration in an imperfectly adherent patient. Our model takes the form of the standard single compartment pharmacokinetic model with first-order absorption and elimination, except that the patient takes medication only at a given proportion of the prescribed dosing times. Doses are missed randomly, and we use stochastic analysis to study the resulting random drug level in the body. We then use our mathematical results to propose principles for designing drug regimens that are robust to nonadherence. In particular, we quantify the resilience of extended release drugs to nonadherence, which is quite significant in some circumstances, and we show the benefit of taking a double dose following a missed dose if the drug absorption or elimination rate is slow compared to the dosing interval. We further use our results to compare some antiepileptic and antipsychotic drug regimens.

Usefulness of extended-release topiramate in patients with epilepsy: A two-year retention study

WHAT IS KNOWN AND OBJECTIVE

Extended-release topiramate (TPM-XR) was recently approved for the treatment of epilepsy, but there is only limited real-world information on the clinical usefulness of TPM-XR in epilepsy patients. We investigated the usefulness of TPM-XR in clinical practice by analysing the retention of TPM-XR in adult epilepsy patients.

METHODS

We performed a single-centre retrospective study covering two years. Epilepsy patients taking TPM-XR were included in the study and classified into one of three groups: the monotherapy group, in which patients took only TPM-XR; the adjunctive therapy group, in which patients took TPM-XR concomitant with other AEDs; and the switching AED regimen group, in which patient's AED was switched from immediate-release TPM (TPM-IR) to TPM-XR. We evaluated the retention rates of TPM-XR and analysed the differences in retention rate among the three patient groups.

RESULTS AND DISCUSSION

We included 164 epilepsy patients who received TPM-XR for the treatment of epilepsy. The overall retention rate of TPM-XR was generally favourable: 79.1% after one year and 77.7% after two years. The switching AED regimen group had a better retention rate than the other two groups (p = 0.04), with a one-year retention rate of 90.6% and a two-year retention rate of 88.1%.

WHAT IS NEW AND CONCLUSION

The favourable retention rate of TPM-XR shows that TPM-XR can be an effective treatment option for epilepsy patients, as either a monotherapy or as an adjunctive therapy. Additionally, switching AED regimen to TPM-XR from TPM-IR can be considered in selected epilepsy patients with poor adherence to TPM-IR.

Risk of hospitalization among patients with epilepsy using long versus short half-life adjunctive antiepileptic drugs

INTRODUCTION

While antiepileptic drugs (AEDs) remain the primary treatment for epilepsy, many patients continue to have seizures. Uncontrolled seizures may be related to AED half-life, since short half-life (SHL) AEDs require more frequent dosing compared with the simplified regimens of long half-life (LHL) AEDs. Long half-life AEDs may also improve seizure control by extending missed dose forgiveness periods. The value of LHL AEDs may be assessed as reduced healthcare utilization. The study's objective was to examine the impact of adding an LHL versus SHL adjunctive AED on the risk of hospitalizations in patients with uncontrolled epilepsy.

METHODS

This was a retrospective, longitudinal cohort study using the Symphony Health Solution Patient Integrated Dataverse. Patients ≥12 years old with uncontrolled epilepsy (≥2 medical claims ≥30 days apart) were identified during a study period (8/1/2012-7/31/2017). Patients were selected if they were subsequently initiated an adjunctive AED (excluding modified release formulations), and the prescription date served as the index. Patients were stratified into two mutually exclusive cohorts based on the index AED half-life (≤20 versus >20 h). Poisson regressions with robust error variances were performed for the relative risks (RRs) of all-cause, epilepsy-related, and injury-related hospitalizations.

RESULTS

A total of 4984 patients were identified (2705 in the LHL and 2279 in the SHL cohort). Compared with those in the SHL cohort, patients in the LHL cohort were significantly younger [mean (SD, years): 43.9 (18.5) versus 49.2 (17.2), p < 0.001] and were less comorbid [mean (SD) of Charlson comorbidity index: 1.2 (1.8) versus 1.8 (2.2), p < 0.001]. In the one-year postindex date, adjusting for group differences, the risks of both all-cause and epilepsy-related hospitalizations were significantly lower in the LHL cohort than in the SHL cohort [all-cause: 0.84 (95% CI: 0.76-0.93), p = 0.0006; epilepsy-related: 0.83 (0.73-0.94), p = 0.0046].Injury-related hospitalizations did not differ between LHL and SHL cohorts.

CONCLUSION

In patients with uncontrolled epilepsy who were initiated on an adjunctive AED, the choice of an LHL versus SHL was associated with significantly lower risks of all-cause and epilepsy-related hospitalizations.

Impact of Medication Regimen Simplification on Medication Adherence and Clinical Outcomes in Patients with Long-Term Medical Conditions

BACKGROUND

This study aims to identify interventions used to reduce medication regimen complexity and to assess their impact on medication adherence and clinical outcomes.

METHODS

A literature search was conducted using pre-defined search terms in three scientific databases, including ScienceDirect, ProQuest and MEDLINE. Original research articles published in English between 2009 and 2020 that assessed the impact of medication regimen simplification on medication adherence in patients with long-term medical conditions were eligible for inclusion. Review articles, meta-analysis studies and conference proceedings were excluded. Data charting was done in an iterative process using a study-specific extraction form.

RESULTS

Of the 684 studies identified through initial searches, 17 studies were included in the review. Nine studies involved simplification of medication regimen related to HIV, while three studies focused on patients with diabetes with or without coronary artery disease. The remaining five studies included medications used among elderly patients or medications related to hypertension, psychiatric disorders, glaucoma and kidney diseases. Three medication regimen simplification strategies were identified; fixed-dose combination (n = 7), once-daily dosing (n = 4) and the combination of both fixed-dose and once-daily dosing (n = 6). Overall, most of the regimen simplification strategies (14 out of 17) were found to be useful in improving medication adherence. There was no assessment of clinical outcomes in four out of 17 studies. Furthermore, more than half of the studies that assessed clinical outcomes did not show any additional impact on clinical outcomes.

CONCLUSION

The findings suggest that there was an equal utilization of the three main approaches of regimen simplifications; fixed-dose combination, once-daily dosing and a combination of both. Overall, most of the regimen simplification strategies were found to be effective in improving medication adherence. However, the associated improvement in medication adherence did not extend to improvement in the clinical outcomes.

Immediate and controlled-release pregabalin for the treatment of epilepsy

Introduction: Epilepsy is a common neurological disease requiring complex therapies, which are unable to achieve seizure control in 30% of patients. Poor adherence has been recognized as a possible determinant of drug-resistance. Prolonged-release formulations of antiepileptic drugs might help increase adherence and minimize side effects.Areas covered: Pregabalin (PGB) has peculiar pharmacodynamics and almost ideal pharmacokinetics, except for a short half-life and therefore requiring multiple daily dosing. PGB immediate-release (IR) is effective in focal-onset epilepsy (FOE), neuropathic pain, generalized anxiety disorder, and fibromyalgia, despite some tolerability issues, especially at higher doses. The controlled-release formulation (CR) shares PGB IR advantages and requires slight dose adjustments to guarantee bioavailability. In 2014, PGB CR (165 and 330 mg/day) failed to prove superior to placebo in a randomized placebo-controlled trial on 323 subjects with drug-resistant FOE, although it was just as tolerable. Therefore, PGB CR is not currently licensed for epilepsy.Expert opinion: Considering the disappointing results of the only controlled trial, PGB CR is unlikely to become an established epilepsy treatment anytime soon. Nevertheless, given its peculiar properties and potential advantages, PGB (in either formulation) should be further evaluated in specific populations of patients, especially fragile subjects with several comorbidities and complex polytherapies.

A Clinician's Guide to Oral Extended-Release Drug Delivery Systems in Epilepsy

Epilepsy is one of the most common chronic neurologic disorders that affects individuals of all ages. It is primarily managed with antiepileptic drugs (AEDs), with the goal of maintaining complete seizure control combined with minimal or no adverse effects. Oral administration is the mainstay of AED delivery for patients with chronic epilepsy and consists essentially of immediate-release (IR) and modified-release (delayed-release and extended-release [ER]) dosage formulations. Extended-release formulations (hydrophilic or hydrophobic matrix systems, reservoir systems, and osmotic-release systems) release a drug in a controlled manner during an extended period of time following administration. Extended-release formulations have many advantages compared with IR formulations, including simplification of dosing regimens, reduction in pill burden, and reduction in the peak-to-trough fluctuations in serum drug concentration that may be associated with a decreased risk of adverse effects and of seizures. These advantages have the potential to increase adherence to antiepileptic therapy, improve the quality of life of patients, and reduce health care costs. This article, which is intended as a practical guide for clinicians, reviews the properties of the different ER AED formulations currently available and discusses the advantages of ER over IR formulations. Subsequently, an explanation of the technologic basis of the different oral ER formulations, the critical attributes that differentiate ER products, and their individual strengths and weaknesses is provided. Specific recommendations to practitioners on treating patients with ER formulations are included.

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.

The application of half-life in clinical decision making: Comparison of the pharmacokinetics of extended-release topiramate (USL255) and immediate-release topiramate

OBJECTIVE

For extended-release drugs with multi-compartment kinetics, such as topiramate, effective half-life (t_1/2eff) may be a more clinically relevant parameter than elimination half-life (t_1/2z). Using topiramate as a real-life example, the objective was to compare these half-life values for immediate- and extended-release topiramate (TPM-IR and USL255, respectively) to understand how drug pharmacokinetics may impact drug dosing recommendations.

METHODS

The t_1/2z and t_1/2eff for USL255 and TPM-IR were compared using data from a phase I study (N=36) of 200mg USL255 administered once daily (QD) or TPM-IR twice daily (BID); effect of sampling duration on t_1/2z was investigated. To further explore the relationship between half-life and dosing, steady-state PK was simulated for USL255 and TPM-IR.

RESULTS

As previously reported, mean t_1/2z was similar between USL255 (80.2h) and TPM-IR (82.8h); TPM-IR t_1/2z was ∼4 times longer than reported in the Topamax label (21h). In contrast, USL255 displayed a 1.5 fold longer t_1/2eff (55.7 vs 37.1h for TPM-IR). When t_1/2z was calculated from 48 to 336h, values ranged from 28.8 to 82.8h. Simulated steady-state PK profiles of USL255 QD exhibited reduced plasma fluctuations during a dosing interval vs TPM-IR QD or BID.

SIGNIFICANCE

As expected for the same moiety, t_1/2z of USL255 and TPM-IR were similar; however, the longer t_1/2eff for USL255 better approximates differences in recommend dosing (QD USL255 vs BID TPM-IR). Further, sampling duration impacted t_1/2z, diminishing its predictive value for determining dose regimens; sampling-time differences may also explain t_1/2z discrepancy between TPM-IR here versus Topamax label. As expected, steady-state simulations confirm that although TPM-IR has a long t_1/2z, taking TPM-IR QD would lead to large plasma fluctuations. These data demonstrate that t_1/2z may be less clinically meaningful than t_1/2eff, and using t_1/2z for some drugs may lead to erroneous conclusions regarding dosing regimens.

Use of computer simulations to test the concept of dose forgiveness in the era of extended-release (XR) drugs

"Forgiveness" - the difference between a drug's postdose duration of action and its prescribed dosing interval - estimates the margin of therapeutic effect following a missed dose. Because this margin presumably decreases as dosing becomes less frequent, QD dosing of an antiepileptic drug (AED) is expected to be less forgiving than more frequent (e.g., BID) dosing of that same AED. However, if the AED is reformulated as an extended-release (XR) preparation, drug input may be prolonged relative to its immediate-release (IR) counterpart. It therefore stands to reason that forgiveness could be increased by an XR AED that extends the period during which therapeutic plasma concentrations are maintained if a dose is missed. Computer simulation was used to estimate forgiveness for an IR formulation of a hypothetical AED and its XR counterparts reformulated for less frequent dosing. Simulations determined forgiveness when the hypothetical IR AED was dosed TID, BID, and QD and when suitably designed XR formulations were dosed BID and QD. Simulations showed that forgiveness for an XR formulation can equal or exceed that for an IR formulation dosed more frequently.

USL255 extended-release topiramate for the treatment of epilepsy

USL255 is a once-daily, extended-release formulation of the well-established antiepileptic drug topiramate that was recently approved by the US FDA. As a capsule formulation, USL255 can be swallowed intact or opened and sprinkled onto soft food for patients with swallowing difficulties, including children (≥2 years old) and older patients. USL255 has been evaluated in seven key Phase I and III studies. Compared with immediate-release topiramate taken twice daily, once-daily USL255 provides equivalent topiramate exposure with a 26% reduction in plasma fluctuations. A multinational, Phase III, randomized, double-blind, placebo-controlled clinical trial in patients with refractory partial-onset seizures (PREVAIL) demonstrated that USL255 (200 mg/day) significantly improved seizure control and clinical outcomes versus placebo. USL255 is generally safe and well-tolerated, with a low incidence of neuropsychiatric and neurocognitive adverse events. These data suggest that USL255 may provide a useful treatment option for seizure control with convenient once-daily dosing.

The practical impact of altered dosing on perampanel plasma concentrations: pharmacokinetic modeling from clinical studies

RATIONALE

Perampanel is a selective AMPA receptor antagonist approved for adjunctive therapy in patients with refractory partial-onset seizures. Perampanel is metabolized primarily via CYP3A4, yet it has a relatively long half-life of 105h; it is, therefore, recommended that perampanel be given once daily (preferably at bedtime). Many patients occasionally have less-than-perfect adherence to their drug regimen, and given the known pharmacokinetic interactions of perampanel with commonly used enzyme-inducing antiepileptic drugs (EIAEDs), we explored the effects of a missed dose on steady-state perampanel plasma concentrations and the ramifications of "make up" doses in these patients. Although perampanel is approved for once-daily dosing, some clinicians may elect to give perampanel as a divided dose (i.e., twice daily), so we also sought to examine the pharmacokinetic impact of twice- versus once-daily dosing.

METHODS

Pharmacokinetic simulations were performed using validated perampanel pharmacokinetic parameters, derived from 19 phase I studies in 606 subjects, to investigate the effect on perampanel plasma concentration of (1) missing a dose of perampanel followed by delayed replacement of the missed dose, (2) missing a dose followed by resumption of scheduled therapy, and (3) missing a dose in the presence/absence of carbamazepine. Simulations were done for a typical patient receiving an 8-mg once-daily or a 4-mg twice-daily dose using the nonlinear mixed effects program, NONMEM v7.2, in conjunction with PDx-pop v5.

RESULTS

Our results corroborate that given the pharmacokinetic characteristics of perampanel, a missed dose is unlikely to cause as much fluctuation in plasma concentration as would be expected for a drug with a short half-life. Importantly, simulations suggest that supplementing a missed dose 6-12h later, followed by continuation of the regular schedule, may not result in any significant "spikes" in perampanel plasma concentrations. Simulations demonstrated that twice-daily dosing offered little advantage in further flattening the concentration-time profile of perampanel in the adherent patient. However, fluctuations in plasma concentrations are minimized by twice-daily dosing in patients receiving concomitant EIAEDs.

CONCLUSIONS

These pharmacokinetic simulations suggest that the long half-life of perampanel may be advantageous in conferring a relatively smooth concentration-time profile with a once-daily or twice-daily dosing, even in the presence of concomitant EIAEDs. However, the results of the present study suggest that perampanel replacement is recommended for patients taking an EIAED to mitigate the potential risks associated with reduced exposure. Confirmation of the ultimate clinical impact of these findings will require further study.

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.

An examination of 1-year adherence and persistence rates to antiepileptic medication in children with newly diagnosed epilepsy

OBJECTIVE

The primary aim of the current study was to use new methods to examine 1-year quality of medication dosing (adherence) and continuation with medication treatment (persistence) rates to antiepileptic drugs (AEDs) in children with newly diagnosed epilepsy.

METHODS

Medication-taking behaviors of AEDs were assessed using electronic monitors for 117 children with newly diagnosed epilepsy for the first year after diagnosis.

RESULTS

Approximately 15% of participants were categorized as nonpersistent (i.e., failed to take medication for >15 consecutive days) 6 months after AED initiation, which increased to 26.6% of participants at 1 year. The majority of medication dosing events took place within a +/-2-hr interval as recommended. The group with lower socioeconomic status demonstrated more nonpersistence over time.

CONCLUSION

Examining adherence and persistence in medication taking behaviors may yield different types of data for clinical and research purposes.

Oxcarbazepine extended-release formulation in epilepsy

Oxcarbazepine (OXC) is a 10-keto-analogue of carbamazepine, which was developed and labeled as a follow-up antiepileptic drug, that was intended to overcome some of the pharmacological drawbacks of carbamazepine with similar efficacy. The main advantage is the nonoxidative metabolic pathway that allows a lower enzyme-induction profile and fewer drug interactions. OXC is rapidly and extensively reduced by cytosolic hepatic enzymes to its monohydroxylated derivative (MHD), thus OXC may be regarded as a prodrug with MHD representing the active antiepileptic agent. The immediate-release (IR) formulation of OXC (Trileptal(®), Timox(®)) has an almost complete bioavailibilty. It is rapidly absorbed and reaches peak concentrations after 1-3 h. MHD peak concentrations are measured within 4-12 h. Elimination half-life in healthy subjects is 1-5 h for OXC and 7-20 h for MHD. The OXC plasma concentration peak may have been responsible for side effects, such as dizziness, vertigo, coordination problems or blurred vision, which appeared more often with this formulation in individual cases than with the formulation available prior to 2000, or with another formulation that has been distributed in Scandinavian countries. Both possibilities offer a profile approaching the characteristics of an extended-release (ER) formulation. ER OXC was labeled in Germany in 2008 (Apydan(®) extent, Desitin Arzneimittel GmbH, Hamburg, Germany). Under steady-state conditions, Phase I studies show bioequivalence between IR and ER OXC. With ER OXC, OXC plasma peak concentrations and both OXC and MHD peak-trough fluctuations are markedly reduced. In clinical trials, comparisons between IR OXC twice daily versus ER OXC once daily failed to show significant differences; efficacy tended to be better with IR OXC, whereas OXC ER showed insignificant tolerability advantages. Another study is currently ongoing to compare the tolerability of both formulations under twice-daily administration conditions in patients with difficult-to-treat epilepsies who require a dosage increase of OXC and who are randomized to IR or ER OXC.

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.

Effects of the abrupt switch from solution to modified-release granule formulation of valproate

BACKGROUND

A new modified-release (MR) granule formulation of valproate (VPA) has been recently developed for the treatment of children with epilepsy. It consists of tasteless microspheres that can be sprinkled on soft foods and easily swallowed. There are no data on the effectiveness of this formulation in pediatric age.

AIM OF THE STUDY

To evaluate the effects of the abrupt switch from solution to VPA MR granules in children undergoing chronic treatment.

METHODS

We enrolled children receiving VPA solution as sole or adjunctive therapy and switched them to MR granules at identical dosages. VPA blood level, treatment efficacy (clinical and EEG data), tolerability (adverse reactions), palatability, ease of administration, and compliance were evaluated before switching (T0) and after 4 weeks (T1).

RESULTS

Out of 112 enrolled children, 108 (96.4%) completed the evaluation. We observed no significant differences between the patients at T0 and T1 in VPA blood levels, treatment efficacy, tolerability, and compliance. MR granules were judged more palatable (P < 0.05) and easier to administer (P < 0.05) than solution by children and parents. At 6-month follow-up, all patients continued to use MR granules.

CONCLUSION

Modified-release granule formulation of VPA may be a reliable alternative to solution for its convenience of use.

Extended-release formulations of antiepileptic drugs: rationale and comparative value

Extended-release products are designed to prolong the absorption of drugs with short half-lives, thereby allowing longer dosing intervals while minimizing fluctuations in serum drug levels. The relationship between serum drug concentration and clinical effects of antiepileptic drugs (AEDs) can be complex and reducing fluctuations in serum drug levels is not equally advantageous for all AEDs. Extended-release formulations have been shown to be particularly valuable for carbamazepine, whereas for other AEDs advantages, other than prolongation of the dosing interval, have not been clearly demonstrated. Differences in bioavailability may exist between extended-release and immediate-release formulations and among different brands of extended-release products. Therefore, when switching from one formulation to another, careful monitoring of clinical response and attention to the need for dose adjustment are warranted.

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.

Levetiracetam extended release and levetiracetam immediate release as adjunctive treatment for partial-onset seizures: an indirect comparison of treatment-emergent adverse events using meta-analytic techniques

The safety profiles of once-daily adjunctive levetiracetam (LEV) extended release (XR) (1000mg/day) and adjunctive LEV immediate release (IR) (500mg twice daily) were compared using data from three randomized, placebo (PBO)-controlled phase III clinical trials in patients with partial-onset seizures. MedDRA 9.0 treatment-emergent adverse events (TEAEs) were indirectly compared using meta-analytic techniques, including calculation of risk difference (RD) and mixed-effects analysis. Statistical significance was set at 10% alpha risk, the normative value for these analyses. Data from 555 patients older than 16 (204 LEV IR, 70 LEV XR, 281 PBO) were analyzed. Following adjustment for incidence of placebo TEAEs, LEV XR showed statistically significantly lower rates of TEAEs than LEV IR across nervous system disorders (RD=-18%, P=0.03), psychiatric disorders (RD=-11%, P=0.08), and metabolism and nutrition disorders (RD=-3%, P=0.08). Among nervous system disorders, the RD for headache favored LEV XR (RD=-11%, P=0.08). These results suggest that adjunctive LEV XR may be associated with a lower incidence of nervous system, psychiatric, and nutritional and metabolic TEAEs as compared with LEV IR. However, this difference was observed at a broad scale and not at a specific TEAE level except for headache.

Best clinical and research practice in epilepsy of older people: Focus on antiepileptic drug adherence

Few studies have examined the issues that are specific to the older person with epilepsy, a population of increasing prominence in epilepsy management. Our understanding of the impact of epilepsy in the older person is based predominantly on what is inferred from studies of younger adults. Consequently, there is relatively little documented about the impact of epilepsy on the everyday lives of older people. In this article, we focus on adherence and its consequences for the physical, social, and psychological well-being of the older person. A number of strategies are proposed to improve adherence, including patient education through better communication between physician and patient; simplification of the medical regime; and use of extended-release formulations. This issue highlights that to ameliorate the impact of epilepsy for the older person with epilepsy, a greater understanding is required so that appropriate interventions can be tailored.

Comparative in vivo bioequivalence and in vitro dissolution of two valproic acid sustained-release formulations

Objective

A study was conducted to establish the bioequivalence between different sustained-release formulations of valproic acid (Depakene R and Selenica R), which were developed in Japan.

Materials and methods

The clinical investigation was designed in a randomized, crossover fashion with a single dose given to 12 healthy subjects. The subjects were administered a single 600 mg dose of valproic acid in one of two formulations. Serial venous blood samples were obtained over 72 hours after each administration to measure valproic acid in serum by enzyme immunoassay (EIA). In addition, a dissolution test was performed. Each sample was analyzed by an high-performance liquid chromatography to determine the dissolution rate of valproic acid.

Results

No difference in maximum concentration or area under the curve was found between the two formulations. The time to maximum concentration of the new formation was significantly delayed compared with the conventional formulation (10.8 ± 1.7 versus 17.6 ± 1.8 hours, p < 0.001). Apparent clearance or elimination half-life did not differ between the two formulations. An in vitro dissolution study showed that Depakene R was significantly more dissoluble than Selenica R.

Conclusion

Based on the results, the present study demonstrated a significant difference between the two sustained-release formulations in the absorption profile, and also demonstrated that the bioavailability of valproic acid in the two formulations was similar but absorption speed (lag time) was very different.

Benzodiazepines in epilepsy: pharmacology and pharmacokinetics

Benzodiazepines (BZDs) remain important agents in the management of epilepsy. They are drugs of first choice for status epilepticus and seizures associated with post-anoxic insult and are also frequently used in the treatment of febrile, acute repetitive and alcohol withdrawal seizures. Clinical advantages of these drugs include rapid onset of action, high efficacy rates and minimal toxicity. Benzodiazepines are used in a variety of clinical situations because they have a broad spectrum of clinical activity and can be administered via several routes. Potential shortcomings of BZDs include tolerance, withdrawal symptoms, adverse events, such as cognitive impairment and sedation, and drug interactions. Benzodiazepines differ in their pharmacologic effects and pharmacokinetic profiles, which dictate how the drugs are used. Among the approximately 35 BZDs available, a select few are used for the management of seizures and epilepsy: clobazam, clonazepam, clorazepate, diazepam, lorazepam and midazolam. Among these BZDs, clorazepate has a unique profile that includes a long half-life of its active metabolite and slow onset of tolerance. Additionally, the pharmacokinetic characteristics of clorazepate (particularly the sustained-release formulation) could theoretically help minimize adverse events. However, larger, controlled studies of clorazepate are needed to further examine its role in the treatment of patients with epilepsy.

Extended-release formulations for the treatment of epilepsy

This review analyses the concept of extended-release (ER) formulations in epilepsy and evaluates ER formulations of carbamazepine, valproic acid and a modified-release (MR) formulation of oxcarbazepine. ER formulations are usually designed to reduce dose frequency and maintain relatively constant or flat plasma drug concentration. It is questionable whether flat plasma concentrations of an antiepileptic drug (AED) improve antiepileptic efficacy compared with fluctuating plasma concentrations. More certainly, they minimise concentration-related adverse effects, and the dosing flexibility and consistency of plasma concentrations may simplify the management of antiepileptic drug therapy. Neurologists would like ER formulations that can be administered once- and/or twice-daily to tailor therapy for the individual patient; however, switching dosage schedules from multiple dosages per day to once daily, although more convenient, will not generally improve therapeutic coverage (maintenance of effective drug concentration in biological fluids and tissue). Pharmacokinetically, the impact of a missed dose is greater the larger the dose and the less frequent the administration. Therefore, the risk of breakthrough seizure is higher during AED once-daily administration than twice-daily administration. Consequently, the increased compliance observed with fewer dosages per day should be weighed against the impact or forgiveness of omitted dose(s) and the shorter 'forgiveness' period associated with once-daily administration. Currently, the trend is to treat patients with epilepsy with ER formulations because of the better compliance, convenience and flat plasma concentration versus time curve. Thus, it seems that the term 'flatter is better' for AED plasma profiles has precipitated in the last 10-15 years among neurologists and epilepsy caregivers, and is being promoted by marketing forces of pharmaceutical companies. Data from the literature support the trend to treat epileptic patients with twice-daily administration of the existing ER formulations of valproic acid and carbamazepine, and oxcarbazepine-MR; however, the author of this article is not convinced that these ER formulations can guarantee a complete therapeutic coverage throughout the 24-hour dosing interval following once-daily administration. Epilepsy is a single-episode disease, and the convenience and possible better compliance associated with once-daily administration must be weighed against the shorter 'forgiveness' period and possible higher risk of breakthrough seizure due to sub-therapeutic plasma levels and/or omitted doses. Data suggest just a small difference in compliance between once- and twice-daily administration, with no significant difference in efficacy. Therefore, the increased compliance following once-daily administration may be counter-productive in minimising the occurrence of sub-therapeutic drug concentrations. Weighing up the advantages and disadvantages for once- versus twice-daily administration of ER formulations in epilepsy leads to a conclusion in favour of twice-daily administration.

Different serum concentrations of steady-state valproic acid in two sustained-release formulations

Recently a new sustained-release formulation of valproic acid has been developed in Japan. The sustained-release mechanism of the new formulation was different from the conventional formulation. The aim of the present study was to compare the pharmacokinetic characteristics of valproic acid in two sustained-release formulations. Different sustained-release formulations of valproic acid (Depakene R and Selenica R) were administered in a randomized cross-over fashion in repeated doses in 24 psychiatric patients. After > or = 4 weeks administration of valproic acid once daily, blood samples were taken just before (0 h) and 8, 12, 24 h after the morning dose. Blood sampling was performed in the same manner in the same patients 4 weeks after switching from one to the other formulation of valproic acid. Serum concentrations of valproic acid at 0 h (50.7 +/- 19.4 vs 44.9 +/- 21.8 microg/mL, P < 0.05) and 24 h (52.3 +/- 19.54 vs 6.2 +/- 22.2 microg/mL, P < 0.05) were significantly higher during Selenica R than during Depakene R treatment, whereas the serum concentration of valproic acid at 8 h (49.7 +/- 19.2 vs 62.4 +/- 25.6 microg/mL, P < 0.01) was significantly lower during Selenica R treatment than during Depakene R treatment. Serum concentrations of valproic acid at 12 h were not different. The present study demonstrated that steady-state serum concentrations were different because of the different dissolution profiles. When a prescription for valproic acid is switched from one drug to the other, prescribers should be aware that the therapeutic drug monitoring data are not consistent.

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.

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.

Patient-reported outcomes in a trial of exenatide and insulin glargine for the treatment of type 2 diabetes

Background

Patient-reported measures can be used to examine whether drug differences other than clinical efficacy have an impact on outcomes that may be important to patients. Although exenatide and insulin glargine appear to have similar efficacy for treatment of type 2 diabetes, there are several differences between the two treatments that could influence outcomes from the patient's perspective. The purpose of the current study was to examine whether the two drugs were comparable as assessed by patient-reported outcomes using data from a clinical trial in which these injectable medications were added to pre-existing oral treatment regimens.

Methods

Patients were randomized to either twice daily exenatide or once daily insulin glargine during a 26-week international trial. At baseline and endpoint, five patient-reported outcome measures were administered: the Vitality Scale of the SF-36, The Diabetes Symptom Checklist – Revised (DSC-R), the EuroQol EQ-5D, the Treatment Flexibility Scale (TFS), and the Diabetes Treatment Satisfaction Questionnaire (DTSQ). Change from baseline to endpoint was analyzed within each treatment group. Group differences were examined with General linear models (GLMs), controlling for country and baseline scores.

Results

A total of 549 patients with type 2 diabetes were enrolled in the trial, and current analyses were conducted with data from the 455 per protocol patients (228 exenatide and 227 insulin glargine). The sample was primarily Caucasian (79.6%), with slightly more men (55.2%) than women, and with a mean age of 58.5 years. Paired t-tests found that both treatment groups demonstrated statistically significant baseline to endpoint change on several of the health outcomes instruments including the DSC-R, DTSQ, and the SF-36 Vitality subscale. GLMs found no statistically significant differences between groups in change on the health outcomes instruments.

Conclusion

This analysis found that both exenatide and insulin glargine were associated with significant improvements in patient-reported outcomes when added to oral medications among patients with type 2 diabetes. Despite an additional daily injection and a higher rate of gastrointestinal adverse events, treatment satisfaction in the exenatide group was comparable to that of the glargine group, possibly because of weight reduction observed in patients treated with exenatide.

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.

Quality of life for patients with epilepsy is determined by more than seizure control: the role of psychosocial factors

Antiepileptic drugs remain the cornerstone of epilepsy treatment for minimizing, if not eliminating, seizures. However, many factors other than the degree of seizure control influence the quality of life for patients with epilepsy. This review focuses on psychosocial factors that have been associated with quality of life in this population, especially mood disorders, stigma seizure worry, self-esteem and self-mastery. Irrespective of their level of seizure control from antiepileptic drugs, patients may also benefit from targeted psychosocial interventions that reduce the negative impact of these factors on their quality of life.

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.

Progress in pharmaceutical development presentation with improved pharmacokinetics: a new formulation for valproate

Successful long-term treatment of patients with epilepsy requires selection of an appropriate antiepileptic regimen, optimal dosing and patient compliance. Recent advances in our understanding of the biological basis of epilepsy and in the choice of treatment options are transforming the global management of these patients. If the achievement of seizure freedom remains the primary goal of any antiepileptic treatment, issues associated with drug acceptability and tolerability, and with quality of life of patients, have gained increasing attention as major determinants of ultimate therapeutic success. Sustained-release formulations of antiepileptic drugs can be very helpful in achieving treatment objectives. Stable serum levels without marked peak-to-trough fluctuations, reduced frequency of dosing and the possibility of dosing flexibility may all improve compliance, patient satisfaction and ultimately quality of life. The efficacy of sodium valproate for the treatment of most types of epilepsy has been demonstrated extensively and this drug remains the mainstay of treatment for many clinical situations. Among the various valproate formulations, extended-release tablets have shown improved patient compliance and satisfaction. However, the tablet size and the limited dosing flexibility could be unsuitable for individualized treatment in special populations such as children, the elderly and patients with swallowing difficulties. A new sustained-release formulation of sodium valproate consisting of tasteless microspheres that can be sprinkled on semi-solid food such as yoghurt or jam has been developed. A stick pack presentation allows individualized dosing and greater convenience.