Search

Brivaracetam (BRV) was recently introduced for the treatment of patients with focal epilepsy. BRV undergoes relatively few interactions, but one of them leads to the elevation of carbamazepine (CBZ)-10,11-CBZ-epoxide (CBZ-E) if BRV is co-administered with CBZ. This interaction has been considered to be clinically negligible. We present a case series of nine patients. In eight of them, levetiracetam (LEV) was switched to BRV. In the remaining case, oxcarbazepine was replaced by CBZ and added to a stable BRV dose. A marked increase of CBZ-E occurred in every case and was associated with clinically relevant symptoms including blurred vision, diplopia, dizziness, or fatigue in three of them. However, in the remaining six, the elevated CBZ-E levels were not associated with any tolerability problems. The importance of CBZ-E for adverse events under CBZ may have been overemphasized in the past and is not clinically impairing in most cases treated with the combination of BRV and CBZ., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Purpose: S100B, a cytokine produced by astrocytes, has been studied as a biomarker of glial and neuronal damage in epilepsy. The present study investigated the reliability of serum S100B as a biomarker and the effect of carbamazepine and oxcarbazepine on serum S100B in patients with focal seizure., Methods: The present randomized, open-label, active-controlled, parallel design clinical trial (NCT02705768) conducted on 60 patients with focal seizure. After recruitment, clinical evaluations were performed including Chalfont-National Hospital seizure severity scale (NHS3), Quality of Life in Epilepsy Inventory (QOLIE-31) and serum S100B was estimated. Thirty healthy individuals were recruited for evaluation of serum S100B at baseline only. After randomization, the study groups received either tablet oxcarbazepine or tablet carbamazepine. At follow-up after 2 weeks, clinical status was checked and at 4 weeks, NHS3 and QOLIE-31 were scored along with serum S100B level estimation., Results: Serum S100B level in patients with focal seizure increased significantly in comparison to healthy volunteers. The decrease in serum S100B was significantly higher with carbamazepine group (0.004; 95% CI 0.001-0.006; p = 0.01) over oxcarbazepine group. In logistic regression analysis, there was an increase in the log odds of 0.17 for focal seizure positivity against healthy controls if S100B level increases by 1 pg and area under curve obtained by ROC analysis was 0.96 (p < 0.001)., Conclusion: Serum S100B increases in the patients with focal seizure and therapy with carbamazepine can decrease serum S100B level significantly over oxcarbazepine. Serum S100B can be used as a prognostic biomarker in a focal seizure.

Neuron-specific enolase (NSE) is the most investigated biomarker in the context of epilepsy and brain damage. The present study was conducted to investigate the change in serum NSE in patients with focal seizure and the effect of carbamazepine and oxcarbazepine on serum NSE. The present study is a randomized, open-label, parallel design clinical trial (ClinicalTrials.gov Identifier: NCT02705768) conducted on 60 patients of focal seizure. After recruitment, detailed history, clinical evaluations including Chalfont-National Hospital seizure severity scale (NHS3), Quality of Life in Epilepsy Inventory (QOLIE-31) and serum NSE estimation were done at baseline. Thirty healthy volunteers were recruited for a baseline evaluation of serum NSE. After randomization, one group received tablet oxcarbazepine and another group received tablet carbamazepine. At 4 weeks follow-up, all the parameter were reassessed. Serum NSE level was found to be significantly increased in patients with focal seizure in comparison to healthy volunteers. In both drug groups, serum NSE decreased significantly but the reduction in carbamazepine group (1.43; 95%CI: 0.18-2.67; p=0.025) was significantly higher than oxcarbazepine group.NHS3 score, score in all seven domains of QOLIE-31 and final QOLIE-31 score improved significantly in both the groups. In conclusion, serum NSE increases in the patients with focal seizure within 48h of a seizure episode. Therapy with carbamazepine and oxcarbazepine can decrease serum NSE level but the reduction is significantly higher with carbamazepine. Therapy with both the drugs can decrease the severity of epilepsy and improve the quality of life but adverse events were more with carbamazepine., (Copyright © 2017. Published by Elsevier B.V.)

BACKGROUND We compared the factors that might impact the severity and the prognosis of carbamazepine (CBZ) intoxication in children, as well as the efficacy levels of the treatment options. MATERIAL AND METHODS Demographic information and clinical and laboratory findings for 40 patients were evaluated retrospectively. Predictive parameters for the development of serious complications were studied. RESULTS Median age of patients was 14 years; 65% of the patients were female. The most common pathological clinical finding and laboratory abnormality were inability to awaken the patient and hyperglycemia (45% and 60%, respectively). The incidences of convulsion, coma, and respiratory failure were 14 (35%), 10 (25%), and 3 (7.5%), respectively. The Glasgow Coma Scale (GCS) scores and pH levels at emergency service admission were significantly lower in the severe intoxication group and the ICU admission group, and body temperature and serum glucose and lactate levels were significantly higher in these groups. A significantly negative correlation was found between the serum CBZ level and the GCS score, but the serum CBZ level was found to be significantly positively correlated with the lactate level. CONCLUSIONS According to our study, the GCS score at admission to hospital, the serum CBZ, glucose, pH, and lactate levels, and body temperature might be useful in predicting serious CBZ intoxication and prognosis in pediatric cases. We conclude that invasive treatment methods, such as hemodialysis or albumin-enhanced continuous venovenous hemodialysis, should be used in patients who do not respond to supportive treatment.

The antiepileptic effect of hydroalcoholic extract of Zizyphus jujuba (HEZJ) in experimental seizures was demonstrated earlier. The present study aimed to evaluate the pharmacokinetic and pharmacodynamic interactions of HEZJ with phenytoin (PHT), phenobarbitone (PB), and carbamazepine (CBZ) in maximal electroshock (MES)-induced seizures in male Wistar rats. Maximal electroshock (70 mA, 9 ms pulse width, 0.2 s) was used to induce seizures. Blood samples were collected at two time points for estimation of serum PHT, PB, and CBZ levels using high-pressure liquid chromatography (HPLC). Co-administration of HEZJ with the sub-therapeutic doses of PHT, PB, and CBZ exhibited 66.7, 66.7, and 50.0% protection against tonic hind limb extension as compared to 33.3, 33.3, and 50% protection respectively, in the groups treated with PHT, PB, and CBZ alone in their sub-therapeutic doses. Co-administration of HEZJ with the sub-therapeutic doses of these antiepileptic drugs (AEDs) showed significant improvement in cognitive functions as compared to MES group as well as these AEDs alone. A significant increase in glutathione levels and decrease in malondialdehyde levels were observed with pretreatment of HEZJ with the sub-therapeutic doses of these AEDs. Co-administration of HEZJ with PHT, PB, and CBZ did not cause any significant changes in the serum concentrations of these AEDs. The results of the present study indicate that the co-administration of HEZJ with sub-therapeutic doses of PHT and PB potentiated the antiepileptic effect of PHT and PB in MES-induced seizures with no change found in the antiepileptic effect of CBZ., (Copyright © 2012 Elsevier Inc. All rights reserved.)

We determined the serum concentration of biotin, zinc, antiepileptic drugs, and biotinidase enzyme activity in 20 children treated with valproic acid, in 10 children treated with carbamazepine, and in 75 age- and sex-matched healthy controls. There were no significant differences in the serum levels of biotin, and biotinidase enzyme activity between the patients treated with valproic acid, the patients treated with carbamazepine, and the control group. Zinc serum levels were lower in the patients treated with valproic acid and with carbamazepine than in the control group, but within the normal range. Hair loss was observed in 3 patients treated with valproic acid, with normal serum levels of biotin, zinc, and biotinidase activity, and the alopecia disappeared with the oral administration of biotin (10 mg/d) in 3 months. These results suggest that the treatment with valproic acid does not alter the serum levels of biotin, zinc, and biotinidase enzyme activity.

Background: Recently, incurred sample reanalysis (ISR) has become a requirement in bioanalysis. The general guidance recommends investigating ISR failure to evaluate the suitability of an analytical method. In the case of acceptable ISR evaluation, there were no precise recommendations for further testing when sporadic values were obtained., Results: The ISR evaluation performed during a bioequivalence study for the anticonvulsant drug oxcarbazepine showed acceptable ISR results, but one particular chromatographic anomaly led to a thorough investigation. The finding of these tests showed that an oxcarbazepine phase II metabolite occasionally co-eluted with the drug and impacted oxcarbazepine's quantitation through in-source conversion., Conclusion: This paper demonstrates the necessity of rigorous interpretation of ISR results and close monitoring of all subject sample results.

There is evidence that valproic acid causes a reduction of serum biotinidase enzyme activity. We determined the serum concentration of antiepileptic drugs, transaminases, gamma-glutamyl transferase, ammonia, and biotinidase enzyme activity in 57 children treated with valproic acid, in 17 children treated with carbamazepine, and in 75 age- and sex-matched healthy controls. There were no significant differences in the serum biotinidase enzyme activity between the patients treated with valproic acid, the patients treated with carbamazepine, and the control group. Hyperammonemia was detected in 8 patients treated with valproic acid. Hair loss was observed in 3 female patients treated with valproic acid, and the alopecia disappeared with the oral administration of biotin (10 mg/ d) in 3 months. These results suggest that the treatment with valproic acid does not alter the serum biotinidase enzyme activity.

Antagonists of steroid receptors may interfere with seizure phenomena. The present study deals with effects of aminoglutethimide and spironolactone on the action of carbamazepine and diphenylhydantoin in amygdala-kindled rats of both genders. Co-administration of the antimineralocorticoid with carbamazepine at their ineffective doses (50 and 15 mg/kg, respectively) led to significant reduction of the seizure and afterdischarge durations. No anticonvulsant effect was observed when spironolactone was combined with diphenylhydantoin. The concomitant treatment of aminoglutethimide and carbamazepine (both drugs at their subprotective doses of 5 and 15 mg/kg, respectively) resulted in antiseizure activity in respect of all measured parameters, including the afterdischarge threshold, seizure severity, seizure duration and afterdischarge duration. The similar combination of aminoglutethimide with diphenylhydantoin (2.5 mg/kg) significantly shortened the seizure and afterdischarge durations. The antiseizure effect of tested combinations was not sex-dependent and not reversed by hydrocortisone pretreatment. Pharmacokinetic events may be involved only in the interaction between spironolactone and carbamazepine. Among various chemoconvulsants, bicuculline reversed the action of aminoglutethimide on carbamazepine and diphenylhydantoin. The effect of aminoglutethimide on diphenylhydantoin was also abolished by N-methyl-d-aspartic acid and aminophylline. In conclusion, our results suggest that doses of carbamazepine and diphenylhydantoin should be modified in epileptic patients concomitantly treated with aminoglutethimide or spironolactone.

Endogenous histamine has been reported to be involved in regulation of seizure susceptibility. Enhancement of histamine neurotransmission engendered by L-histidine treatment produces anticonvulsant effects in experimental animals. The present study investigated the influence of L-histidine on the protective effects of carbamazepine and phenytoin against maximal electroshock-induced seizures in mice.L-Histidine, administered at the doses that did not influence the threshold for electroconvulsions (250-500 mg/kg), enhanced by nearly 30% the protective effects of carbamazepine against maximal electroshock-induced seizures. D-Histidine (1000 mg/kg), an inactive isomer of histidine, was without any effect in this regard. L-Histidine (500 mg/kg) also augmented the protective effects of phenytoin. Importantly, the enhancement of the anticonvulsant effects of these antiepileptic drugs produced by L-histidine co-administration was not associated with augmentation of their unwanted effects on memory and motor performance. A pharmacokinetic interaction was also excluded since the free plasma levels of these antiepileptics remained unchanged in the presence of L-histidine. It may be suggested that L-histidine could serve as a beneficial adjuvant for selected antiepileptic drugs.

Aim: To assess the appropriateness of the determination of the serum levels of the antiepileptic drugs (AEDs) phenytoin, valproic acid and carbamazepine in inpatients of a tertiary care institution., Methods: We performed a retrospective analysis of 602 AED serum level determinations. Appropriateness criteria regarding indication and timing were defined a priori using existing criteria from the literature. The main outcome measure was the proportion of serum levels with an appropriate indication and sampling time., Results: Of 602 levels assessed, 463 (77%; 95% confidence interval [95% CI], 74-80%) had an appropriate indication with a range of 68% to 84% for individual AEDs; overall, 65% (95% CI: 61-69%) met the criteria for appropriate timing. Combining the two criteria, 268 (48%; 95% CI: 44-52%) AED level measurements were assessed as appropriate. Of 139 (23%, 95% CI: 20-27%) levels assessed as having an inappropriate indication, the majority (77%) were performed for routine monitoring., Conclusions: Less than half of all AED measurements met our criteria for appropriate AED level determinations. This creates unnecessary costs. Our data indicate the need for means to improve the rational use of AED serum level determination.

Amlodipine, a calcium channel antagonist of the dihydropyridine class, up to 10 mg kg(-1)(i.p.) did not significantly affect the threshold for electroconvulsions. However, this calcium channel antagonist (10 mg kg(-1)) enhanced the anticonvulsive activity of carbamazepine, valproate and phenobarbital against maximal electroshock-induced seizures in mice. Furthermore, amlodipine (5 mg kg(-1)) intensified the protection offered by carbamazepine. This effect was associated with the increased free plasma level of carbamazepine in the presence of amlodipine. Amlodipine did not influence the free or total plasma level of phenobarbital and valproate, so a pharmacokinetic interaction is not probable for valproate and phenobarbital. The anticonvulsive action and free plasma level of diphenylhydantoin was not modified by amlodipine. The combined treatment of the calcium channel antagonist and antiepileptics caused motor impairment (evaluated in the chimney test). Long-term memory (assessed in the passive avoidance test) in case of combinations of amlodipine with carbamazepine or diphenylhydantoin was not affected. The combination of amlodipine with valproate or phenobarbital significantly influenced the retention in this test. A possible usefulness of amlodipine as add-on therapy in epileptic patients may be limited by its considerable adverse effect revealed by behavioural tests. The pharmacokinetic interaction between carbamazepine and amlodipine might have some clinical importance for patients treated with these drugs., (Copyright 1999 Academic Press.)

Two single-center, open-label studies examined the potential effects of tiagabine on the pharmacokinetics and safety of carbamazepine and phenytoin at steady state. Twelve adult patients with seizures controlled by an individualized fixed dosage of antiepilepsy medication (carbamazepine or phenytoin) participated in each study. On day 1, the pharmacokinetics of the baseline antiepilepsy drug were determined. On days 2 through 18, tiagabine was titrated from 8 to 48 mg/d (or the maximum tolerated dose up to 48 mg/d), and the usual fixed dosage of carbamazepine or phenytoin was continued. The pharmacokinetic assessment was repeated on day 18. There were no statistically significant differences in carbamazepine, carbamazepine epoxide, and phenytoin pharmacokinetic parameters when either drug was administered alone or in combination with tiagabine. In each study, 11 of 12 patients (92%) experienced treatment-emergent adverse events after tiagabine was added. The most frequent adverse events were dizziness, headache, difficulty concentrating, drowsiness, and tremor. Most symptoms were mild or moderate in severity and resolved without further treatment, although tiagabine dosage reductions were required by 4 patients in the carbamazepine study and by 3 patients in the phenytoin study. There were no clinically important effects on physical examination or neurologic test results, laboratory values, or vital signs. The results suggest that addition of tiagabine to a fixed regimen of either carbamazepine or phenytoin is generally well tolerated and that carbamazepine and phenytoin steady-state pharmacokinetics are unaffected by the addition of tiagabine.

Objective: To address the paradox that phenytoin- and carbamazepine-treated patients have decreased serum free thyroxine (T4) and triiodothyronine (T3) concentrations but appear clinically euthyroid and have normal serum thyroid-stimulating hormone (TSH) concentrations., Design: In vitro studies comparing measurements of total and free T4 and T3 by ultrafiltration assay (undiluted serum) and a commercial free T4 estimate kit in control serum samples or serum samples containing added therapeutic levels of phenytoin or carbamazepine. These measurements were made in serum samples diluted 1:5 with either identical serum or phospate buffer, pH 7.4, and in serum samples from patients with seizure disorders who were treated with phenytoin or carbamazepine., Setting: A 650-bed teaching hospital., Patients: Selected patients (n=19) who were in good health except for seizure disorder, with stable anticonvulsant drug levels in the upper half of the therapeutic range, and were not taking any other drugs that could affect thyroid parameters., Main Outcome Measure: Serum concentrations of free T4 and free T3 in patients taking phenytoin or carbamazepine vs normal controls., Results: Addition of phenytoin or carbamazepine to normal human serum in vitro resulted in a significant increase in free T4 fraction and free T4 (P<.001). In patients taking phenytoin or carbamazepine, serum total T4 decreased significantly to 60% and 74%, respectively, of the control serum concentration (P<.001 for both phenytoin and carbamazepine); free T4 fraction (by ultrafiltration assay) increased 65% and 44%, respectively (P<.001 for phenytoin, P<.01 for carbamazepine); and free T4 remained unchanged. Free T4 concentration measured by a commercial kit (1:5 serum dilution) was significantly lower than the control concentration in both phenytoin- and carbamazepine-treated patients. Serum free T3 and serum TSH were also normal in phenytoin- and carbamazepine-treated patients., Conclusions: Therapeutic levels of phenytoin and carbamazepine displace T4 and T3 from serum binding proteins. When added to serum, the drugs effect an increase in free hormone fractions and free T4 and T3. In drug-treated patients, increased free T4 and T3 fractions offset the significant decrease in serum T4 and T3, resulting in normal free T4 and free T3 concentrations. Since currently available clinical tests will continue to show decreased free T4 concentrations in patients taking phenytoin or carbamazepine, clinicians should rely on serum TSH measurements to confirm the euthyroid status of these patients.

An analysis of maximal and minimal serum concentrations of carbamazepine was performed in 40 children with convulsive syndrome. All the patients received the drug for a long period. Considerable case-to-case differences of serum concentrations in spite of practically equal doses were revealed. Serum drug concentrations were therapeutically optimal (6-8 mg/ml) only in one third of children. On the basis of pharmacokinetic parameters, mean optimal dosages sufficient for maintenance of effective and safe carbamazepine concentrations were calculated. As the child grows general clearance of carbamazepine decreases. Over the age of 9 years it is significantly lower in girls than in boys of the same age. Speed of carbamazepine elimination was higher in cases of combined treatment than in cases of monotherapy. Indications and optimal time for therapeutic drug monitoring of carbamazepine are determined and clinical illustrations are presented.

Generic substitution is practiced widely in both hospital and community settings. There have been several reports of reduced serum concentrations and seizure exacerbation following generic substitution of Tegretol. We describe the first 2 cases of carbamazepine toxicity resulting from the substitution of Tegretol with Epitol. Two 6-year-old children experienced increases in the maximum serum carbamazepine concentration, one of 22% and one of 41%. Both became asymptomatic when their serum concentrations were lowered and had no residual effects.

Antiepileptic drug (AED) levels are obtained frequently in clinical practice, but their complex relation to seizures or drug toxicity often makes interpretation of the results difficult. Research studies have not always taken into account clinical, as well as pharmacokinetic and pharmacodynamic, factors which may influence the drug level-effect relationship. AED levels should be drawn at an appropriate time in relation to drug ingestion and clinical symptoms. Systematic investigations in selected patients, during which several levels are obtained, may be more rewarding than routine measurements in a large clinic population.

We sequentially determined carbamazepine clearance values in 17 patients at the end of weeks 1, 2, 4, 8, and 12 of monotherapy. There were no significant differences among these clearance values. In 11 of 17 patients, week 1 clearance accurately predicted week 12 carbamazepine serum concentration (within +/- 33%). Our data indicate that carbamazepine autoinduction was completed within the first 1 or 2 weeks of monotherapy. Serum concentration values obtained after 1 week of monotherapy, using our dosing regimen, can be used to predict directly the dosing rate needed to obtain a specific serum concentration in most patients.

Progabide (PGB) is a gamma-aminobutyric acid (GABA)-agonist drug undergoing clinical evaluation for the treatment of spasticity, movement disorders, and epilepsy. Drug interactions were studied during a randomized, double-blind, crossover trial of the efficacy and toxicity of PGB in patients with partial seizures taking phenytoin (PHT) and carbamazepine (CBZ). In twenty-two of 32 patients (69%) receiving PGB, PHT dosage was reduced, while only four patients (12%) had their dosage reduced during placebo treatment (p less than 0.001). Carbamazepine dosage was decreased in five of 32 patients (16%) during the active treatment, while two patients (6%) had a dosage reduction when receiving placebo (p greater than 0.75). The mean PHT concentrations at the end of baseline, PGB, and placebo treatments were significantly different: 17.5, 20.4, and 16.8 mg/L, respectively (p less than 0.05). Nevertheless, careful adjustment of PHT dosage maintained serum concentration within +/- 25% of target values in both the PGB and placebo periods. Among patients who first received PGB and then placebo, PHT concentrations remained elevated relative to dose suggesting that PGB exerts a prolonged effect on PHT disposition. The addition of PGB to regimens including PHT results in a significant increase in serum PHT concentrations. This drug interaction most likely occurs as a result of PGB mediated inhibition of hepatic microsomal enzymes.

A 2 1/2-year-old child being treated with carbamazepine (CBZ) for a seizure disorder on two separate occasions experienced elevated CBZ serum concentrations (28 and 23.2 mg/L), severe liver damage (SGOT greater than 6000 IU, SGPT greater than 5000 IU), and central nervous system manifestations (coma, lethargy, seizures). During the first episode, the time course of CBZ concentrations exhibited a nonlinear decline and was accompanied by CBZ-10,11-epoxide concentrations that were elevated 4-fold compared to normal values. Cerebrospinal fluid concentrations of CBZ and CBZ-10,11-epoxide were also elevated, although their ratios to serum concentrations did not suggest enhanced permeability of the central nervous system to these substances. The concentrations of CBZ-10,11-epoxide but not CBZ were elevated for the duration of time that the patient was comatose, suggesting that this metabolite may contribute to the neurotoxic side effects observed with CBZ therapy.

Effects of carbamazepine on alcohol withdrawal seizures and symptoms were studied in rats. Carbamazepine was administered during alcohol feeding and continued during alcohol withdrawal. When carbamazepine serum levels were above 3 micrograms per milliliter, alcohol withdrawal seizures were not observed. Carbamazepine also alleviated alcohol withdrawal symptoms, especially heightened spontaneous activity, startle to noise, stereotyped chewing movements, and intermittent body stiffening.

In a previous study on carbamazepine (Lockard et al., 1974), the problem of its low bioavailability in solid form and its short half-life in monkey were addressed. The present research was designed to evaluate carbamazepine under constant-rate intravenous infusion in our alumina-gel monkey model. Since carbamazepine is insoluble in an aqueous solution, polyethylene glycol 400 was used as the vehicle for administration of this drug to a group of 8 epileptic monkeys. The attenuation of seizures by carbamazepine was not statistically significant since the serum levels of carbamazepine after enzyme induction were less than 2.0 micrograms/ml. This study (a) illustrates that some problems in drug evaluation may be insoluble with our present technology even though we are cognizant of them; (b) makes explicit the fact that the efficacy of carbamazepine is a function of adequate serum levels; (c) demonstrates endogenous oscillations of carbamazepine serum concentrations; and (d) reports simultaneous serum levels of carbamazepine and its 10--11 epoxide in the monkey model.