Priscila Freitas-Lima

Addressing overtreatment in patients with refractory epilepsy at a tertiary referral centre in Brazil

BackgroundPatients with refractory epilepsy often have impaired quality of life (QOL) as a consequence of seizures and adverse effects of antiepileptic drugs. We assessed the impact of adverse effects on QOL and the utility of a structured instrument to help the physician manage adverse effects in patients with refractory epilepsy.MethodsClinical characteristics, drug treatment and adverse effects were evaluated in 102 patients with refractory epilepsy at a single tertiary referral centre. The Adverse Events Profile (AEP) and Quality of Life in Epilepsy-31 (QOLIE-31) questionnaires were completed at baseline and after six months. At baseline, patients with a high burden of adverse effects (AEP scores ≥45) were randomized to an intervention or control group. AEP scores in the intervention group were available to the physician as an instrument to help to reduce adverse effects.ResultsNinety-five patients (93.1%) were on polytherapy. Sixty-six completed the questionnaires and, of these, 43 (65.1%) had a high AE burden and were randomized to the intervention and control group. QOLIE-31 scores were inversely correlated with AEP scores at both visits. Among randomized patients, AEP scores tended to decrease between the baseline and the final visit without significant differences between groups (intervention group: 54.1±6.1 vs 51.1±9.1; control group: 55.8±5.8 vs 50.5±12.2). QOLIE-31 scores did not change substantially between visits (intervention group: 45.9±17.4 vs 48.4±14; control group: 47.5±15.7 vs 45.2±18.9).ConclusionA significant proportion of patients had a high toxicity burden which had an impact on their QOL. Reduction of overtreatment is a difficult challenge which cannot be addressed solely by providing a structured assessment of adverse effects, but requires a more comprehensive approach aimed at optimizing the many components of the management strategy.

Influence of enzyme inducing antiepileptic drugs on the pharmacokinetics of levetiracetam in patients with epilepsy

To assess whether levetiracetam elimination is influenced by enzyme inducing antiepileptic drugs (EIAEDs), serum levetiracetam levels were determined at frequent intervals after a single oral 1000mg dose in 15 subjects co-medicated with EIAEDs and 15 matched controls. The EIAED group showed a higher levetiracetam oral clearance (p=0.01) and a shorter half-life (p=0.02) than controls. Although the magnitude of interaction is relatively modest, it could have clinical significance for some patients.

An investigation of the influence of patient-related factors and comedications on lamotrigine clearance in patients with epilepsy

Lamotrigine (LTG) is one of the most widely used antiepileptic drugs. Confusion still exists in the literature as to the relative influence of age, body weight, and concomitant drug therapy on LTG pharmacokinetics. So, the objective of this study is to evaluate the influence of patient‐related factors and comedication on LTG apparent oral clearance (CL/F). A therapeutic drug‐monitoring database was used to identify steady‐state plasma LTG concentrations in 210 patients. LTG CL/F values were calculated for each patient according to the equation CL/F (L/h per kg) = LTG daily dose (mg/kg)/Css (steady state concentration) (mg/L) × 24 h. A linear‐regression model was used to assess the influence of gender, dose, age, and body weight in LTG CL/F. The influence of comedication on LTG CL/F was investigated by applying the Bonferroni post‐test. The lowest LTG CL/F was found in patients comedicated with valproate (VPA) (mean, 0.0183 L/h per kg), followed by patients receiving VPA + enzyme inducers (0.0271 L/h per kg), patients on LTG monotherapy (0.0298 L/h per kg) and patients comedicated with enzyme inducers (0.056 L/h per kg) LTG CL/F correlated significantly with LTG dose (P < 0.01), but showed no significant relationship with gender, weight, and age. LTG CL/F is influenced by the type of antiepileptic comedication. The correlation with dose may be a spurious finding related to the fact that physicians, in adjusting dosage according to clinical response, are more likely to use larger doses in patients with high clearance values.

The social context and the need of information from patients with epilepsy: evaluating a tertiary referral service

OBJECTIVE Characterize the social profile and the need of information from patients with refractory epilepsy. METHOD A semi-structured questionnaire was applied to 103 patients to investigate sociodemographic aspects, pharmacotherapy and any doubts about epilepsy. RESULTS Patients were highly dependent on having a free and accessible supply of antiepileptic drugs. Sixty-eight percent of the population was unemployed, and 26% confirmed receiving social security benefits due to epilepsy. Twenty-nine percent of the population reached high school. Eighty-five percent of the patients had at least one doubt about epilepsy; treatment and epilepsy aspects in general were the main topics. CONCLUSION As observed in developed countries, patients with refractory epilepsy from a developing country also have high rates of unemployment and low educational levels. The results raise a concern about the need of information about epilepsy by patients and their families, urging the necessity to invest in strategies to solve this deficiency in knowledge.

Drug utilization profile in adult patients with refractory epilepsy at a tertiary referral center

OBJECTIVE To evaluate the utilization profile of antiepileptic drugs in a population of adult patients with refractory epilepsy attending a tertiary center. METHOD Descriptive analyses of data were obtained from the medical records of 112 patients. Other clinical and demographic characteristics were also registered. RESULTS Polytherapies with ≥3 antiepileptic drugs were prescribed to 60.7% of patients. Of the old agents, carbamazepine and clobazam were the most commonly prescribed (72.3% and 58.9% of the patients, respectively). Among the new agents, lamotrigine was the most commonly prescribed (36.6% of the patients). At least one old agent was identified in 103 out of the 104 polytherapies, while at least one new agent was prescribed to 70.5% of the population. The most prevalent combination was carbamazepine + clobazam + lamotrigine. The mean AED load found was 3.3 (range 0.4-7.7). CONCLUSION The pattern of use of individual drugs, although consistent with current treatment guidelines, is strongly influenced by the public health system.

Drug-resistant epilepsy and topiramate: Plasma concentration and frequency of epileptic seizures

Topiramate (TPM) is a second‐generation antiepileptic drug (AED), acting on drug‐resistant epilepsy. The aim of the study was to evaluate the influence of the dose, use of other AEDs on TPM plasma concentration (Cp), and frequency of epileptic seizures. A cross‐sectional analytical study was developed with patients aged 18‐60 years, for diagnosis of drug‐resistant epilepsy, using TPM in monotherapy or associated with other AEDs. The following variables were analyzed: age, frequency of epileptic seizures, pharmacotherapeutic regimen with its respective doses, adherence to medication treatment, and adverse events score. Thirty‐seven patients were included, 83.8% of the patients presented Cp below the therapeutic range. Multiple linear regression estimated that the increase of 1.0 mg/kg/d promoted an increase of 0.68 μg/mL in TPMCp, while the use of inducers predicted a reduction of 2.97 μg/mL (P < .001). Multiple Poisson regression predicts that an increase of 1.0 μg/mL in TPMCp decreased the patients chance of presenting seizures, and patients using AED inducers were about ten times more likely to present seizures than those who do not use (P < .001). In addition, for patients using AED inducers with Cp below the therapeutic range, the mean number of seizures per month was greater than those with Cp within the therapeutic range. The prescribed dose and the use of AED inducers influence Cp of TPM, likewise the low Cp of first‐line AEDs and of the adjuvant in the treatment, TPM, as well as low TPM dose seem to affect the control of epileptic seizures.

Stir bar-sorptive extraction, solid phase extraction and liquid-liquid extraction for levetiracetam determination in human plasma: comparing recovery rates

Levetiracetam (LEV), an antiepileptic drug (AED) with favorable pharmacokinetic profile, is increasingly being used in clinical practice, although information on its metabolism and disposition are still being generated. Therefore a simple, robust and fast liquid-liquid extraction (LLE) followed by high-performance liquid chromatography method is described that could be used for both pharmacokinetic and therapeutic drug monitoring (TDM) purposes. Moreover, recovery rates of LEV in plasma were compared among LLE, stir bar-sorptive extraction (SBSE), and solid-phase extraction (SPE). Solvent extraction with dichloromethane yielded a plasma residue free from usual interferences such as commonly co-prescribed AEDs, and recoveries around 90% (LLE), 60% (SPE) and 10% (SBSE). Separation was obtained using reverse phase Select B column with ultraviolet detection (235 nm). Mobile phase consisted of methanol:sodium acetate buffer 0.125 M pH 4.4 (20:80, v/v). The method was linear over a range of 2.8-220.0 µg mL-1. The intra- and inter-assay precision and accuracy were studied at three concentrations; relative standard deviation was less than 10%. The limit of quantification was 2.8 µg mL-1. This robust method was successfully applied to analyze plasma samples from patients with epilepsy and therefore might be used for pharmacokinetic and TDM purposes.