Alternate endpoints for seizure measurement

The type of seizure measurement selected should be tailored to the needs of the clinical trial. These needs change as the development of the investigational agent moves along. Protocol designers who look toward nontraditional outcome measures might acquire valuable data that could be used to differentiate their drug from other new treatments. Most importantly, as clinical trials evolve into effectiveness studies, clinicians are provided with useful data on which to base selection of a drug of first choice to treat each type of seizure disorder.

Development and cross-cultural translations of a 31-item quality of life in epilepsy inventory

PURPOSE

We report the development of a questionnaire to assess health-related quality-of-life (HRQOL) in people with epilepsy and the process of cross-cultural translations of the questionnaire.

METHODS

A sample of 304 adults with epilepsy from 25 seizure clinics in the United States was used to derive an abbreviated questionnaire focusing on epilepsy-related issues from a longer, 89-item instrument (QOLIE-89). A rigorous forward-backward-forward system was used for cross-cultural translation.

RESULTS

A 31-item questionnaire (QOLIE-31, version 1.0) resulted, comprising seven subscales covering general and epilepsy-specific domains. Subscale and total scores can be calculated. The subscales were grouped into two factors: Emotional/Psychological Effects (seizure worry, overall QOL, emotional well-being, energy/fatigue subscales) and Medical/Social Effects (medication effects, work-driving-social limits, cognitive function subscales). Cross-cultural translations were made from U.S.-English into Danish, Dutch, German, Canadian French, French, Italian, Spanish, Swedish, and U.K. English Versions 1.1.

CONCLUSIONS

Our results support the reliability and validity of the QOLIE-31 (U.S.-English version 1.0) as a measure of HRQOLIE. Cross-cultural translations into nine other languages make it feasible to use the QOLIE-31 (version 1.1) in multinational clinical trials after validation in each population or concurrent with the clinical trial.

Enhancing patient compliance in the elderly. Role of packaging aids and monitoring

Inadequate compliance with medications is a significant contributor to the costs of medical care in every therapeutic area. No matter how severe the consequence, there is no assurance that all patients will take their medications as prescribed. Elderly patients are a particular concern because of their common deficits in physical dexterity, cognitive skills and memory, and the number of medications that they are typically prescribed. To overcome problems of compliance in the elderly, healthcare providers are advised to prescribe a simple dosage regimen for all medications to be taken (preferably 1 or 2 doses daily), to help the patient select cues that assist them in remembering to take doses (time of day, meal-time, or other daily rituals), to provide devices to simplify remembering doses (medication boxes), and to regularly monitor compliance. A variety of compliance aids are available to help patients organise their medications (e.g. plastic boxes) or remember dose times (alarms). Medication packaged in standard pharmacy bottles should be identified with special labels, or dose charts can be provided to check the daily schedule. Single-unit doses, widely used in hospitals, may be cumbersome for elderly patients who have difficulty opening the foil-backed wrappers. Medication boxes with compartments that are filled weekly by the patient, family member or a home healthcare provider are useful organisers that simplify the patient's responsibilities for self-administration. Microelectronic devices can provide feedback that shows patients whether they have been taking doses as scheduled. Some systems are also designed to notify patients within a day if doses were omitted. No system is optimal for all patients, but elderly patients deserve a comprehensive assessment of their needs to enhance medication compliance.

Quality of life as an outcome measure for epilepsy clinical trials

Assessment of health-related quality of life (HRQOL) has been developed to the point where well-validated instruments are being used in clinical trials. Data on the impact of new treatments can be used for formulary and regulatory decisions if the clinical trials are designed with appropriate instruments and sample sizes. However, more information is needed about the clinical significance of small differences in total or scale scores. Similarly, pharmacoeconomic studies should be prospective assessments that include evaluation of HRQOL as well as cost. In the future, these new aspects of outcome assessment are expected to be used as an adjunct to traditional seizure frequency and adverse effect reports in the selection of antiepileptic drugs.

A tandem solid phase extraction, reversed-phase HPLC method for determining SDZ WAG 994 in dog, monkey and rat blood

The development and validation of a sensitive and specific HPLC method for SDZ WAG 994 (I) in dog, monkey and rat blood is described. Sample preparation entailed double solid phase extraction (SPE) of I and the internal standard from 0.5 ml of animal blood using a phenyl and propyl sulfonic acid cation exchange column, sequentially. Chromatographic separation was achieved on a YMC Basic C-8 narrowbore HPLC column and the eluates were detected by UV absorption at 266 nm. The method has a linear response up to at least 1800 ng/ml with a limit of quantification of 1 ng/ml across all species. Analysis of 'blinded' quality control dog and monkey blood samples over 3 or 4 days produced median precisions of 2.89 and 4.77%, and median reproducibilities of 4.86 and 10.9%, respectively. Curve fitting of variability estimates indicated that concentration independent error contributed 3-9% of the total method error for the tandem SPE procedure. Extracted endogenous material from blood matrices, several potential metabolites and cyclohexyladenosine were well resolved from the peaks of interest. The stability of I in dog blood stored at -20 degrees C is at least 6 months. The overall absolute and relative recovery of I using the tandem SPE procedure was 85.5 +/- 5.1% and 96.5 +/- 5.0%, respectively. The ruggedness of the method has been demonstrated by multiple analyses, from several toxicokinetic studies, performed by different analysts using comparable instrumentation.

The effect of food on the pharmacokinetics of multiple-dose terbinafine in young and elderly healthy subjects

Pharmacokinetic (PK) parameters for terbinafine were assessed in 15 elderly and 15 young healthy subjects randomized to receive 250 mg Lamisil once daily for 15 d in a two-period, two-treatment, two-sequence, crossover (fed versus fasted) design within age groups. On each treatment day except days 8 and 15, subjects took Lamisil with food at 8:00 a.m. On days 8 and 15, subjects took the drug under either fed or fasting conditions according to treatment sequence, and 24 h PK profiles were obtained. Two analyses of the pharmacokinetic data were undertaken. In a noncompartmental analysis, AUC0-24h, Cmax, C0h, and tmax were computed for each subject on each of days 8 and 15, and the influences of food condition and age on these variables were assessed by analysis of variance. AUC0-24h and C0h were found to be larger (p < 0.5) among elderly subjects than young subjects on day 15, and tmax was prolonged (p < 0.05) under the fed condition on day 15. Similar trends on day 8, as well as generally higher exposures under the fed condition on both days, were not statistically significant. A three-compartment model fitted to the complete sequence of 33 terbinafine concentrations measured over 29 d for each subject separately permitted a within-subject assessment of the food effect that confirmed prolonged absorption and increased bioavailability (p < 0.05) under the fed condition. Across-subject comparisons of oral clearances estimated with the model also confirmed the increased exposures (lower clearances) among the elderly (p < 0.05). The drug was well tolerated in both age groups. In particular, greater drug exposure in the elderly did not result in greater toxicity, as indicated by the safety evaluations in the study.

Effect of valproate on cognitive functioning. Comparison with carbamazepine. The Department of Veterans Affairs Epilepsy Cooperative Study 264 Group

OBJECTIVE

To assess the effects of carbamazepine vs valproate sodium on cognitive functioning in patients with epilepsy compared with normal control subjects.

DESIGN

Patients with recently diagnosed, previously unmedicated seizures participated in a prospective randomized double-blind Department of Veterans Affairs multicenter study of the efficacy and toxicity of carbamazepine vs valproate.

MAIN OUTCOME MEASURE

A behavioral toxicity battery was administered prior to treatment and again 6 and 12 months after the initiation of antiepileptic medication.

RESULTS

There were no significant differences in the effect of carbamazepine vs valproate on motor speed and coordination, memory, or concentration and mental flexibility, and there was no significant decline in neuropsychological performance from pretreatment baseline levels for either drug. No significant differences in performance were found between patients with low (mean, 52.8 micrograms/mL) vs high (mean, 94.4 micrograms/mL) serum valproate levels within the therapeutic range. Patients treated with either carbamazepine or valproate did not show practice effects experienced by normal controls, a finding that may reflect a subtle compromise in cognitive functioning.

CONCLUSION

The impact of carbamazepine and valproate monotherapy on cognitive functioning is similar: both drugs produce minimal negative effects compared with pretreatment baseline performance.

Compliance with contraceptives and other treatments

OBJECTIVE

To define some of the issues unique to compliance with oral contraceptives, and some comparisons with other preventive and therapeutic treatments.

DATA SOURCES

Reports of compliance with medical treatment were used, with a focus on studies using microelectronic monitoring to assess compliance. Studies included the general population and a variety of demographically different groups.

METHODS OF STUDY SELECTION

Twenty-nine studies of medication compliance (including surveys and clinical trials with specific interventions), across a broad range of medical disorders, were selected for comparison with reports of oral contraceptive compliance.

TABULATION, INTEGRATION, AND RESULTS

Rates of compliance with contraceptive methods are low, but differ little from rates of compliance with other medical treatments. Several questions might be used to ascertain the likelihood that an individual is willing to use an oral contraceptive as prescribed (eg, willingness to take a daily pill, to return for follow-up, and to report adverse effects).

CONCLUSIONS

Studies of a variety of medical disorders have shown that no consequence is so severe that all patients can be assumed to comply with the prescribed treatment plan. Inadequate compliance often diminishes treatment efficacy, which suggests the need for alternative methods that do not require daily compliance.

Prognosis for total control of complex partial and secondarily generalized tonic clonic seizures. Department of Veterans Affairs Epilepsy Cooperative Studies No. 118 and No. 264 Group

BACKGROUND

Two prospective observations of adults with symptomatic, localization-related (partial) epilepsy included 1,102 patients in VA multicenter studies (VA-118 and VA-264). Analyses assessed the likelihood of remaining seizure free for 12 and 24 months after initiating adequate antiepileptic drug therapy.

METHODS

Patients were grouped as having only secondarily generalized tonic-clonic seizures (GTC), only complex partial seizures (CPS), or both types (MIXED) at entry. The cumulative proportion of patients remaining seizure free with standard antiepileptic drug therapy was determined by actuarial life table methods.

RESULTS

At 12 months, 70% and 61% of GTC patients (VA-118 and VA-264, respectively) had no further GTC; 53% and 50% of MIXED, predominantly GTC patients had no further GTC, 21% and 28% of CPS patients had no further CPS and 98% and 91% were seizure free for GTC; 32% and 35% of MIXED, predominantly CPS patients had no further CPS, and 62% and 51% of patients with MIXED seizure types remained seizure free for CPS for 12 months after enrollment.

CONCLUSIONS

The overall prognosis for control of seizures of any type for 12 months was best for those who had only GTC at entry (55% and 48%), worst for those who had only CPS at entry (23% and 26%), and intermediate for those with MIXED seizures at entry (32% and 25%) (all p < 0.0001). Prognosis can be based on the predominant seizure type in patients with multiple types.

A brief questionnaire to screen for quality of life in epilepsy: the QOLIE-10

PURPOSE

To evaluate a brief questionnaire to screen aspects of health-related quality of life for persons with epilepsy.

METHODS

A study of 304 adults with epilepsy was undertaken at 25 seizure clinics in the United States. It was used for derivation of a brief screening tool from a longer instrument (QOLIE-89).

RESULTS

The 10-item questionnaire (QOLIE-10) covers general and epilepsy-specific domains, grouped into three factors: Epilepsy Effects (memory, physical effects, and mental effects of medication), Mental Health (energy, depression, overall quality of life), and Role Functioning (seizure worry, work, driving, social limits). Scale scores were significantly different among seizure groups (p = 0.003).

CONCLUSIONS

The QOLIE-10 can be completed by a patient in several minutes and reviewed rapidly by the physician. This screening tool could provide potentially useful information for initial assessment or follow-up of problem areas that are not commonly evaluated during routine clinical visits with patients with epilepsy.

Pharmacokinetics and pharmacodynamics of multiple-dose terbinafine

Data from clinical trials of terbinafine for the treatment of onychomycosis were analyzed with the following two objectives: 1) to identify demographic predictors of the duration and extent of systemic drug exposure; and 2) to explore whether increased systemic exposure or demographic predictors of increased exposure were associated with altered safety or efficacy. Demographic predictors of exposure were identified by a model-free, nonparametric approach applied to the sparse pharmacokinetic data from the onychomycosis studies. Those covariates were then incorporated into a multicompartmental nonlinear mixed effects model. Post hoc parameter estimates from the nonlinear mixed effects model provided individual measures of exposure. Safety scores were derived for adverse events that were frequently attributed to drug exposure and for liver function tests. Terbinafine was found to have an average terminal half-life (t1/2) of approximately 3 weeks. That terminal elimination phase contributed so little to the total exposure, however, that average concentrations accumulated only approximately two-fold at steady state with once daily dosing. Age and concomitant hypertension were predictors of higher plasma concentrations of terbinafine; smokers had lower levels than nonsmokers. Although some statistically significant associations between adverse events and systemic exposure were found, in all cases the actual frequency of the adverse events and systemic exposure were found, in all cases the actual frequency of the adverse events was low, and there were no trends in severity with respect to exposure. Above-normal levels of gamma-glutamyl transferase were associated with exposure, but there was no trend in severity with respect to exposure. No other liver function test abnormalities were associated with exposure, nor were there any significant associations between adverse events or liver function abnormalities and demographic subgroups that differed with respect to exposure. Among patients taking the active drug there were no significant associations between exposure levels and efficacy, nor were there differences in efficacy between demographic subgroups that differed with respect to exposure.

Safe coadministration of terbinafine and terfenadine: a placebo-controlled crossover study of pharmacokinetic and pharmacodynamic interactions in healthy volunteers

The pharmacokinetic and pharmacodynamic interactions of terbinafine (Lamisil) and terfenadine (Seldane) were assessed in 26 healthy volunteers randomized to receive either terbinafine (250 mg tablet) or its placebo (terbinafine placebo), which were administered in a double-blind manner once daily for 18 days. On days 12 through 18, terfenadine was coadministered (60 mg twice daily, unblinded). Pharmacokinetic profiles were obtained for terbinafine and its desmethyl metabolite on day 11 (in the absence of terfenadine), day 12, and day 18. Terfenadine and terfenadine acid metabolite levels were also assayed on days 12 and 18. After a 4-week washout period, subjects were crossed over to the alternate treatment (terbinafine or terbinafine placebo). Pharmacodynamic measures were electrocardiographic (ECG) rhythm abnormalities, corrected QT interval (QTc), and plasma ALT levels. Terfenadine levels were evaluated; however, only eight of 1502 samples assayed were above the limit of quantitation. No effect of terbinafine administration on pharmacokinetic parameters for the terfenadine acid metabolite was observed, except for a decrease of approximately 20% in through terbinafine concentrations (C0hr; p < 0.05) on the last day of terfenadine plus terbinafine coadministration. Pharmacokinetic parameters for terbinafine were unchanged on the first day of terfenadine coadministration, and only small increases in area under the plasma concentration versus time curve from 0 to 24 hours and peak plasma concentrations (16.1%[p < 0.01] and 6.63% [p < 0.05]) were observed on the last day of terfenadine and terbinafine coadministration. Values for C0hr were also about 20% to 25% higher (p < 0.05). Steady-state levels of the terfenadine acid metabolite were achieved after 2 days of terfenadine coadministration, and steady-state levels of terbinafine and its desmethyl metabolite were achieved after 14 days of terbinafine administration. The incidence of ECG rhythm abnormalities was not significantly higher in any treatment group; however, the incidence of prolongation of QTc > 10% above baseline was significantly higher in the groups treated with terfenadine. No QTc prolongation occurred in the absence of terfenadine treatment. Both terbinafine and terfenadine were well tolerated when coadministered during this study, as indicated by the low incidence of complaints, abnormalities, and adverse events. The results of this study indicate that terbinafine and terfenadine can be safely coadministered.

The relationship of neuropsychological functioning to quality of life in epilepsy

OBJECTIVE

To examine the relationship of objectively assessed cognitive functioning to self-reported quality of life.

DESIGN

Correlational, multiple regression, and factor analytic comparisons of a new self-report quality of life inventory with neuropsychological tests of cognition and mood.

SUBJECTS

Two hundred fifty-seven patients with epilepsy.

SETTING

Twenty-five epilepsy centers and neurology clinics across the United States.

MEASURES

A recently developed self-report (ie, Quality of Life in Epilepsy-89 inventory) and objective tests of memory, verbal abilities, spatial functions, psychomotor and cognitive processing speed, cognitive flexibility, and mood.

RESULTS

Factors that assessed mood, psychomotor speed, verbal memory, and language correlated significantly with selected scales of the Quality of Life in Epilepsy-89 inventory (P < .0001) and were predictive of overall quality of life (P < .002 to P < .0001). The mood factor showed the highest correlations (r = -.20 to r = -.73) and was the strongest predictor of quality of life in regression analyses (46.7% explained variance, P < .0001).

CONCLUSIONS

Mood may be adversely affected by diminished quality of life, or perceived quality of life may be affected by mood disturbance. Quantitative quality of life assessments can be used in conjunction with formal neuropsychological testing of mood and cognition when evaluating patients with epilepsy.

Optimizing long-term patient compliance

The key elements for enhancing patient compliance when prescribing are selecting the fewest number of daily doses (taking patient's other medications into consideration), scheduling when doses are to be taken, and helping the patient select an appropriate reminder or "cue." Developing reminder cues, such as clock time, meal time, or bathroom ritual, requires only a few minutes of careful planning to mesh with the patient's lifestyle. If one type of cue is not successful, another or combinations of cues are tried over time. Asking patients about their cues at each visit not only helps patients develop personalized cuing systems, but also reminds them that their physician has a consistent interest in the way they take their medication. Unfortunately, no single specific strategy will enhance compliance in all patients. Physicians have the greatest influence on medication compliance when they provide specific suggestions that fit into the patient's lifestyle.

Kinetic and mechanistic studies with bovine testicular hyaluronidase

Bovine testicular hyaluronidase exhibits hydrolase and transglycosylase activity. To assess the magnitude of each type of reaction, the time-course of hyaluronidase catalysed hyaluronic acid degradation was followed using a sensitive and specific HPLC method. The kinetic parameters Km and Vmax were calculated for purified short chain hyaluronic acid oligomers and native hyaluronic acid based on the appearance of unreactive hyaluronic acid tetrasaccharide. For hyaluronic acid oligomers, as substrate size increased Km decreased from 2.06 to 1.09 mM while Vmax remained about the same, indicating a 5-fold increase in the enzyme-substrate association constant, k1 (kcat/Km). The values of k2 (kcat), the enzyme-substrate disassociation constant, for native hyaluronic acid and hyaluronic acid decasaccharide were similar. The value of k1 for native hyaluronic acid, however, was larger by 70-fold. Kinetic degradation mechanisms for each hyaluronic acid oligomer, using chemical-reaction kinetics, were proposed and evaluated by computer curve fitting analysis of the experimental time vs. concentration data. The derived rate constants, together with mass balance calculations, revealed that transglycosylation plays a significant role in the degradation of all hyaluronic acid oligomers studied.

Measurement of carbamazepine and carbamazepine epoxide in the human brain using in vivo microdialysis

We report the first study of carbamazepine and carbamazepine-10,11-epoxide concentrations determined by using intracerebral microdialysis in three patients undergoing depth electrode studies for the evaluation of medically intractable epilepsy. Very small microdialysis catheters, affixed to and inserted with the depth electrodes, sampled drug concentration in the extracellular environment. We perfused artificial extracellular fluid continuously, and varied the perfusion rate to permit estimation of the absolute drug concentration in the extracellular space. Serum samples were obtained simultaneously. The relation between dialysate and extracellular concentration (recovery fraction) depended, in vivo but not in vitro, on the relative lipophilicity of the compounds, suggesting that diffusion of the drug within the brain is a major determinant of microdialysate drug concentration. When this is taken into account, the steady-state extracellular concentrations of these compounds closely mirror their unbound serum concentrations.

Phenytoin concentrations in the human brain: an in vivo microdialysis study

We report the first human study of phenytoin concentration using in vivo microdialysis, which permits sampling the extracellular environment of the brain. This technique has been applied to patients undergoing intracranial electrode investigation for intractable epilepsy. By varying the rate of perfusion (from 2.5 to 0.25 microliters/min), it is possible to quantify the concentration of drug in the extracellular fluid (ECF), which reflects the concentration on the outer neuronal cell membrane. Samples were obtained from four catheters in two patients, in whom serum phenytoin (PHT) concentrations were held constant. Unbound serum concentrations were measured following ultrafiltration at 37 degrees C. In one patient, with left and right hippocampal probes, steady state ECF/unbound serum ratios were 87 and 84% respectively. In the second patient, with hippocampal and frontal probes, ECF/unbound serum ratios were 87 and 85% respectively. Flow rate for 50% maximal recovery averaged 1.65 microliters/min (1.5-1.7 microliters/min). We found that steady state ECF PHT concentrations corresponded closely to unbound serum concentrations. No differences are observed between different sites within the brain. Flow rates needed for equilibration of dialysate with the extracellular space were slower than reported for carbamazepine, but faster than those we found for carbamazepine-epoxide and valproate.

A pharmacodynamic approach to the estimate of carbamazepine autoinduction

Population-based pharmacokinetic prediction algorithms have been developed for several medications. A fundamental assumption has been that the kinetics remain constant over time. Carbamazepine (CBZ), however, induces its own metabolism in a concentration- and time-dependent manner. A Bayesian estimation program is presented that models the changing catabolic enzyme activity, linearly related to hepatic microsomal enzyme concentration, along with the serum drug concentration. An Emax model is used for enzyme formation with respect to drug concentration: elimination of enzyme activity is modeled as a first-order process. This program was tested in 22 drug-naive outpatients begun on CBZ monotherapy. The 1 week concentrations were used to prospectively predict concentrations at 1 month of therapy and were very close to actual measurements: prediction bias (mean error of prediction) = -0.1 micrograms/mL and precision (median absolute error of prediction) = 1.2 micrograms/mL. Comparison estimates, made by assuming a constant concentration/dose ratio, had bias = 2.6 micrograms/mL (p < 0.001) and precision = 2.2 micrograms/mL (p = 0.01). We conclude that (1) CBZ autoinduction is not complete after 1 week of therapy and (2) the methodology permits accurate estimation of CBZ pharmacokinetics.

Quality of life for people with epilepsy

The diversity and impact of problems related to epilepsy require each patient to develop a concept of what issues are most important, and seek to address these issues as a personal priority. Domains to be considered include physical, psychological, social, and epilepsy-specific issues. Level of independence is also an important concern. Quality of life instrument scores are a new measure of overall patient function. Use of well constructed, validated instruments specific for disease or general function will enhance the ability of health care providers to understand changes in patients that are not readily discernible without an extensive interview.

A clinimetric approach to assessing quality of life in epilepsy

Clinimetrics is a concept involving the use of rating scales for clinical phenomena ranging from physical examinations to functional performance. Clinimetric or rating scales can be used for defining patient status and changes that occur during long-term observation. The scores derived from such scales can be used as guidelines for intervention, treatment, or prediction of outcome. In epilepsy, clinimetric scales have been developed for assessing seizure frequency, seizure severity, adverse effects related to antiepileptic drugs (AEDs), and quality of life after surgery for epilepsy. The VA Epilepsy Cooperative Study seizure rating scale combines frequency and severity in a weighted scoring system for simple and complex partial and generalized tonic-clonic seizures, summing all items in a total seizure score. Similarly, the rating scales for systemic toxicity and neurotoxicity use scores weighted for severity for assessing specific adverse effects typically related to AEDs. A composite score, obtained by adding the scores for seizures, systemic toxicity, and neurotoxicity, represents the overall status of the patient at a given time. The Chalfont Seizure Severity Scale also applies scores relative to the impact of a given item on the patient, without factoring in seizure frequency. The Liverpool Seizure Severity Scale is a patient questionnaire covering perceived seizure severity and the impact of ictal and postictal events. The UCLA Epilepsy Surgery Inventory (ESI-55) assesses quality of life for patients who have undergone surgery for epilepsy using generic health status instruments with additional epilepsy-specific items.(ABSTRACT TRUNCATED AT 250 WORDS)