Serum carnitine levels during oxcarbazepine and carbamazepine monotherapies in children with epilepsy

Prolonged antiepilepsy drug treatment can result in secondary carnitine deficiency. The effect of oxcarbazepine on carnitine metabolism has not been reported previously. In this study, serum concentrations of total and free carnitine were measured in 20 children with epilepsy treated with oxcarbazepine monotherapy and were compared with 20 children with epilepsy who were taking carbamazepine as monotherapy. The assays were performed between 3 and 6 months of anticonvulsant treatment. The mean values of serum total and free carnitine levels in patients receiving carbamazepine monotherapy were 63.0 +/- 20.7 micromol/L and 49.1 +/- 16.7 micromol/L, respectively. The mean values of serum total and free carnitine levels in patients receiving oxcarbazepine monotherapy were 64.2 +/- 17.4 micromol/L and 50.3 +/- 13.7 micromol/L, respectively. The values were all between normal ranges. No significant difference was observed in the level of total and free carnitine levels between the two groups. Our results suggest that neither oxcarbazepine nor carbamazepine as monotherapy causes carnitine deficiency in otherwise healthy children with primary idiopathic epilepsy.     

Hyperhomocysteinemia in children treated with sodium valproate and carbamazepine

OBJECTIVE: To evaluate plasma homocysteine (Hcy) concentrations in children receiving sodium valproate (VPA) and carbamazepine (CBZ), monotherapy, in comparison with healthy control subjects and to determine the possible relationship between Hcy levels and dosage and plasma concentrations of the antiepileptic drugs. METHODS: We measured levels of fasting and post-methionine Hcy, plasma pyridoxal 5'-phosphate (PLP, active vitamin B6), serum folate, erythrocyte folate and serum vitamin B12 in 60 epileptic patients (29 females, 31 males), aged from 14.2 to 17.9 years, subdivided into two groups according to their therapy. Sixty-three healthy sex- and age-matched children served as controls. These measurements have been performed before the beginning of therapy and after 1 year of therapy with VPA or CBZ. RESULTS: Before the beginning of therapy, there were no significant differences in fasting and post-methionine Hcy, plasma PLP, serum folate, erythrocyte folate and serum vitamin B12 values between the control group and the two groups of epileptic children. After 1 year of therapy, patients treated with VPA and CBZ showed a significant increase of the plasma concentrations of Hcy when compared to baseline data and controls values. Moreover, was observed a significant decrease of serum folate and plasma PLP. On the contrary, serum vitamin B12 and erythrocyte folate levels remained in the normal range. CONCLUSIONS: Our study demonstrates that prolonged treatment with VPA and CBZ increases plasma concentrations of Hcy.     

The cognitive effects of oxcarbazepine versus carbamazepine or valproate in newly diagnosed children with partial seizures

OBJECTIVE: To investigate the effect of oxcarbazepine against standard antiepileptic drug therapy (carbamazepine and valproate) on cognitive function in children and adolescents (aged 6 to <17 years) with newly diagnosed partial seizures. METHODS: A multicentre, open-label, randomised, active-control, three-arm, parallel-group, 6-month study. The primary cognitive variable, the Computerized Visual Searching Task (CVST), assessed mental information processing speed and attention. Secondary variables included additional tests assessing psychomotor speed, alertness, memory and learning, and non-verbal intelligence. RESULTS: Of 112 patients randomised, 99 completed the study. The dropout rate was 11.6%; 13 patients discontinued due to adverse events (n=5) or unsatisfactory therapeutic effect (n=8). Mean CVST time decreased in all groups, indicating an improvement of mental processing speed and no cognitive impairment in any treatment group. No statistically significant difference was observed between oxcarbazepine and combined carbamazepine/valproate. Analysis of secondary variables did not show statistically significant differences between oxcarbazepine, carbamazepine and valproate. Analysis of intelligence test results showed that the number of correct answers increased at end point in all groups. The percentage of patients remaining seizure free throughout treatment was comparable across all groups (oxcarbazepine 58%; carbamazepine 46%; valproate 54%; carbamazepine/valproate 50%). The most common adverse events were fatigue and headache for oxcarbazepine, fatigue and rash for carbamazepine, and headache, increased appetite and alopecia for valproate. CONCLUSION: Oxcarbazepine treatment over 6 months does not display any differential effects on cognitive function and intelligence in children and adolescents with newly diagnosed partial seizures relative to standard antiepileptic drug therapy. No impairment in cognitive function was observed in any treatment group over a 6-month period.     

Effects of carbamazepine and oxcarbazepine on the reproductive endocrine function in women with epilepsy

PURPOSE: The aim of the study was to compare the effects of carbamazepine (CBZ) and oxcarbazepine (OXC) on the reproductive endocrine function in women with epilepsy. OXC is a novel antiepileptic drug (AED), and the occurrence of reproductive dysfunction in women treated with OXC monotherapy for epilepsy has not been studied previously. METHODS: Thirty-five women with epilepsy were examined in the Department of Neurology at Oulu University Hospital. Sixteen patients were treated with CBZ monotherapy, and nineteen patients were treated with OXC monotherapy. The subjects were clinically examined, vaginal ultrasonography was performed, and serum sex hormone concentrations were measured. RESULTS: The women taking CBZ or OXC had lower serum testosterone (T) levels and lower free androgen indexes (FAIs) than the control subjects. CBZ medication was associated with increased concentrations of serum sex hormone-binding globulin (SHBG). The patients taking OXC had higher concentrations of dehydroepiandrosterone sulfate (DHEAS) and androstendione (A) than did the women taking CBZ. Moreover, the prevalence of polycystic ovaries (PCOs) was high in the OXC-treated women. CONCLUSIONS: CBZ and OXC have different effects on the reproductive endocrine function. Although both drugs were associated with low serum T concentrations and low FAIs, only OXC was associated with a high frequency of elevated levels of A and DHEAS and with an increased prevalence of PCOs. These findings suggest that OXC may be disadvantageous for women with epilepsy and hyperandrogenism, whereas CBZ may be beneficial for these women.     

Thyroid function in girls with epilepsy with carbamazepine, oxcarbazepine, or valproate monotherapy and after withdrawal of medication

Summary: Purpose: Antiepileptic drugs may affect the serum thyroid hormone concentrations. The aim of this study was to evaluate thyroid function in 78 girls taking carbamazepine (CBZ), oxcarbazepine (OXC), or valproate (VPA) monotherapy for epilepsy and after withdrawal of the treatment. Methods: Forty‐one girls taking VPA, 19 taking CBZ, and 18 taking OXC for epilepsy, as well as 54 healthy age‐matched controls, aged 8 to 18 years, participated in the study. All the girls were examined clinically, and their pubertal stage was assessed. Blood samples were obtained for thyroid hormone and antibody assays. These examinations were repeated after a mean follow‐up of 5.8 years to assess thyroid function, and 64 (82%) of 78 patients and 42 (78%) of 54 controls agreed to participate in the second evaluation. Results: In the first evaluation, the mean serum thyroid hormone concentrations were lower in the girls taking CBZ [thyroxine (T₄), 70.2; SD, 10.9 nM; and free thyroxine (FT₄), 11.5; SD, 1.8 pM] or OXC (T₄, 74.9; SD, 16.4 nM; and FT₄, 11.3; SD, 1.8 pM) than in the control girls (T₄, 96.6; SD, 15.1 nM, and FT₄, 14.4; SD, 1.5 pM; p < 0.001, all comparisons). However, thyrotropin (TSH) concentrations were normal in the girls taking CBZ or OXC. Sixty‐three% of the girls taking CBZ and 67% of the girls taking OXC had serum T₄ and/or FT₄ levels below the lower limit of the reference range. The VPA‐treated girls with epilepsy had normal serum T₄ and FT₄ concentrations, but slightly increased TSH levels (3.3; SD, 1.5 mU/L; p < 0.01) compared with the control girls (2.5; SD, 1.0 mU/L). Normal serum hormone concentrations were restored in the patients who discontinued the medication. Conclusions: Both CBZ and OXC reduce serum thyroid hormone concentrations in girls with epilepsy. Conversely, VPA is associated with normal serum thyroid hormone and increased thyrotropin levels. However, our results suggest that the changes in serum thyroid hormone and thyrotropin levels are reversible after withdrawal of the medication.     

Comparison of oxcarbazepine and carbamazepine: a double-blind study

The antiepileptic efficacy and side-effects of oxcarbazepine (OXC), a new carbamazepine derivate, were evaluated in a double-blind study. Forty ambulatory epileptics with unsatisfactory seizure control or unwanted effects due to phenytoin monotherapy were changed to OXC or carbamazepine (CBZ) and were then followed for 48-50 weeks. Thirty-four of the patients completed the study. The seizure frequencies on the trial drugs were not significantly different and the antiepileptic efficacy of OXC was comparable to CBZ. The incidence of side-effects during the initiation phase was lower with OXC suggesting better tolerability of OXC compared to CBZ.     

Reproductive effects of valproate, carbamazepine, and oxcarbazepine in men with epilepsy

BACKGROUND: Recent observations have indicated that reproductive endocrine disorders are common among women taking valproate (VPA) for epilepsy, but it is not known whether respective abnormalities develop in men taking VPA for epilepsy. Carbamazepine (CBZ) may induce endocrine disorders in men with epilepsy, but the endocrine effects of oxcarbazepine (OXC) are not known. METHODS: Reproductive endocrine function was evaluated in 90 men taking VPA (n = 21), CBZ (n = 40), or OXC (n = 29) as monotherapy for epilepsy and in 25 healthy control men. RESULTS: Twelve men (57%) taking VPA had increased serum androgen levels. The mean serum level of androstenedione was high in patients taking VPA. Serum levels of dehydroepiandrosterone sulfate were low, and serum concentrations of sex hormone-binding globulin (SHBG) were high in men taking CBZ. The endocrine effects of OXC seemed to be dose-dependent, because serum hormone levels were normal in patients with low OXC doses (< 900 mg/day), but serum concentrations of testosterone, gonadotropins, and SHBG were high in patients with a daily OXC dose > or = 900 mg. CONCLUSIONS: VPA increases serum androgen concentrations in men with epilepsy. The endocrine effects of CBZ and OXC were different, because CBZ appears to decrease the bioactivity of androgens, whereas OXC does not.     

Early and persistent increase in serum lipoprotein (a) concentrations in epileptic children treated with carbamazepine and sodium valproate monotherapy

PURPOSE: The aim of this study was to investigate by a prospective, self-controlled method, whether treatment with carbamazepine (CBZ) and sodium valproate (VPA) monotherapy may alter serum lipoprotein (a) [Lp(a)] concentrations in epileptic children. METHODS: Serum Lp(a) concentrations have been determined in 18 epileptic children before and at 6, 12 and 24 months of treatment with CBZ monotherapy and in 30 epileptic children before and at 6, 12 and 24 months of treatment with VPA monotherapy. Serum total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, apolipoproteins A-I and B concentrations and serum concentrations of biochemical markers of liver and renal function were also measured in the study participants. RESULTS: Serum Lp(a) concentrations were significantly increased at 6, 12 and 24 months of CBZ and VPA monotherapy. There were no significant correlations between serum Lp(a) and serum lipids, lipoproteins, apolipoproteins, concentrations of biochemical markers of liver and renal function or antiepileptic-drugs concentrations. CONCLUSIONS: Children who receive CBZ or VPA monotherapy may have significant and persistent increase in serum lipoprotein (a) concentrations, occuring early in the course of therapy. It may be useful to measure serum Lp(a) concentrations routinely in epileptic children taking these antiepileptic drugs, especially in those that are already at higher atherosclerotic risk.     

The effect of carbamazepine and sodium valproate on the blood and serum values of children from a third-world environment

In third-world countries many children with epilepsy also suffer from malnutrition, anemia, liver disease, and immunosuppression. Doctors might have reservations about the use of anticonvulsants that could aggravate these disorders. The purpose of this study was to establish the prevalence of abnormal blood and serum values in children receiving carbamazepine or sodium valproate as monotherapy who attended a child neurology clinic serving a third-world community in Cape Town, South Africa Blood samples were taken at routine follow-up visits from 104 children who had been on carbamazepine or sodium valproate monotherapy for at least 6 months. Hematology, serum chemistry, immunoglobulins, and anticonvulsant levels were measured by standard laboratory procedures. Very few subjects had any values outside accepted normal ranges. When clinically indicated and available, carbamazepine and sodium valproate can be prescribed for children from a third-world environment. Frequent blood and serum testing is not necessary in asymptomatic individuals.     

Conversion from carbamazepine or oxcarbazepine to topiramate in adolescents and adults with epilepsy

Objective – To explore effectiveness, tolerability and changes in quality of life in patients with epilepsy converting to topiramate (TPM) from carbamazepine (CBZ) or oxcarbazepine (OXC) due to insufficient effectiveness and/or tolerability. Methods – A multicenter, open‐label, non‐interventional trial was used to examine patients (≥ 12 years) with epilepsy, changing to TPM monotherapy from baseline mono‐ or combination therapy with CBZ or OXC. TPM was added to the existing antiepileptic drug (AED) treatment and started at a dose of 25 mg once daily. The dose was titrated up with 25 mg/day increments, once every 1–2 weeks, until a final dose between 50 and 200 mg/day was reached. On the basis of clinical judgment, the treating physician decided whether or not the existing AED treatment with CBZ or OXC could then be withdrawn. Type and number of seizures, preferred TPM dose, quality of life (QOLIE‐10 questionnaire), subjective perception of improvement and adverse events (AE) were documented. Results – 140 patients (53.5% women, mean age 47 years) decided to switch to TPM due to insufficient effectiveness (75% of patients) and/or poor tolerability (80%) of the CBZ/OXC treatment. Average duration of follow‐up was 24 weeks with an overall discontinuation rate of 19.3%, mainly due to AEs (12.1%). At study endpoint, the intended shift to TPM monotherapy was achieved in 73% of patients at a median TPM dose of 100 mg/day. A seizure reduction of ≥ 50% was achieved in 91% of patients in the last scheduled period (weeks 12–26); 62% of patients entering that period remained seizure free. Quality of life at endpoint improved significantly when compared with baseline for all domains of QOLIE‐10 (P < 0.001). Most frequent AEs (reported by ≥ 5% of patients) were paresthesia (9.3%), weight loss (7.9%), convulsions (5.7%) and memory disorders (5.0%). Conclusion – In patients with epilepsy, previously not satisfactorily treated with CBZ or OXC, conversion to TPM may result in an improvement in seizure control as well as in quality of life.     

Comparison of the effects of carbamazepine and oxcarbazepine on peripheral nerve conduction

Twenty-five epileptic outpatients were studied to assess possible effects of the first 6 months of treatment with carbamazepine or oxcarbazepine using serial peripheral nerve conduction measurements. Carbamazepine caused a small slowing effect on the motor conduction of the median nerve after 4 weeks of treatment, and the effect was correlated with the fasting serum concentration of the drug. Slowed motor conduction value of the median nerve was also observed after 6 months of treatment with carbamazepine. Oxcarbazepine did not cause any statistically significant slowing of nerve conduction.     

Early effect of sodium valproate and carbamazepine monotherapy on homocysteine metabolism in children with epilepsy

Plasma total homocysteine (p-tHcy), serum folate (s-F), serum vitamin B-12 (s-B12) and plasma pyridoxal-5'-phosphate (p-PLP) were measured in epileptic children before and after a 20-week period of sodium valproate (group A, n=32) and carbamazepine (group B, n=20) monotherapy. P-tHcy significantly increased in both groups, s-F and s-B12 significantly increased in group A, while s-F and p-PLP significantly decreased in group B. Our study showed an early effect of antiepileptic drug treatment on homocysteine metabolism.     

Total and free serum concentrations of carbamazepine and carbamazepine-10,11-epoxide in children with epilepsy

Simultaneous steady-state serum total and free (non-protein-bound) concentrations of carbamazepine and carbamazepine-10,11-epoxide were measured in 68 patients under the age of 21 years with epilepsy (44 males, 24 females; mean age, 11.8 +/- 4.5 years). Thirty patients were maintained on monotherapy with carbamazepine. Mean serum total carbamazepine and carbamazepine-10,11-epoxide concentrations obtained were 7.0 +/- 2.4 mg/L (29.5 +/- 10.0 mumol/L) and 1.5 +/- 0.6 mg/L (5.9 +/- 2.6 mumol/L), respectively. Mean serum-free carbamazepine and carbamazepine-10,11-epoxide concentrations obtained were 1.3 +/- 0.5 mg/L (5.7 +/- 2.1 mumol/L) and 0.5 +/- 0.3 mg/L (2.2 +/- 1.1 mumol/L), respectively. Binding of carbamazepine and carbamazepine-10,11-epoxide was 81% +/- 3% and 62% +/- 10%, respectively. There was no significant difference in binding between male and female patients or those maintained on monotherapy and polytherapy. Age correlated significantly with carbamazepine binding but not with carbamazepine-10,11-epoxide binding. Free concentrations of carbamazepine and carbamazepine-10,11-epoxide correlated significantly with total carbamazepine and total carbamazepine-10,11-epoxide concentrations, respectively, indicating that the binding capacities of both carbamazepine and carbamazepine-10,11-epoxide are constant at serum total carbamazepine concentrations within the quoted therapeutic range.     

Effects of oxcarbazepine treatment on serum lipids and carotid intima media thickness in children

The aim of this study is to evaluate the carotid intima media thickness and serum lipids in pediatric patients with epilepsy treated with oxcarbazepine. The study included 21 pediatric epileptic and 22 healthy children. Intima media thickness and fasting lipid profile were assessed. Although the median value of total cholesterol was in normal limits in the oxcarbazepine group, it was significantly higher when compared with the control group. We did not observe any differences regarding triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and carotid intima media thickness. We suggest that oxcarbazepine treatment in children has a minor effect on serum lipids and it does not seem to have an atherogenic effect.     

Factors influencing serum levels of carbamazepine and carbamazepine-10,11-epoxide in children

Carbamazepine-10,11-epoxide (CBZ-E), the principal metabolite of carbamazepine (CBZ), is reported to have antiepileptic and toxic effects similar to CBZ. Steady-state CBZ and CBZ-E levels (high performance liquid chromatography, HPLC assay) were reviewed in 225 outpatient children and young adults taking CBZ with or without other antiepileptic drugs (AEDs). In patients on CBZ alone, mean serum concentration of CBZ was 7.9 +/- 1.9 micrograms/ml and of CBZ-E was 1.5 +/- 0.6 micrograms/ml. The CBZ-E/CBZ ratio was 19.6 +/- 2.4%. Serum CBZ increased with increasing age and with CBZ dose. CBZ-E increased with increasing CBZ dose but was unaffected by age. The CBZ-E/CBZ ratio progressively declined with age. Co-medication with barbiturates or valproic acid significantly increased CBZ-E. Phenytoin showed a similar trend while ethosuximide caused the least change. Patients on CBZ and two or more other AEDs had highest CBZ-E levels and CBZ-E/CBZ ratio. CBZ and CBZ-E levels are variably affected by age, CBZ dose, and co-medication with other AEDs. When other AEDs are administered, careful monitoring is especially indicated in order to avoid toxicity.