Is brivaracetam-induced elevation of carbamazepine-epoxide levels common and clinically relevant? - A case series.

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.

A randomized, double-blind comparison of antiepileptic drug treatment in the elderly with new-onset focal epilepsy.

OBJECTIVE: To compare the effectiveness of controlled-released carbamazepine (CR-CBZ) to levetiracetam (LEV) and to lamotrigine (LTG) in elderly patients with newly diagnosed focal epilepsy. METHODS: Randomized, double-blind, parallel-group trial conducted between January 2007 and August 2011, in 47 ambulatory or hospital sites in Germany, Austria, or Switzerland. Eligible participants were aged ≥ 60, had new-onset epilepsy, had no acute illness as the cause of their seizures, and had no contraindication to the drugs in the trial. Patients were randomized 1:1:1 to CR-CBZ, LTG, or LEV. Doses were up-titrated for 6 weeks and could be maintained or adjusted depending on seizure relapse or tolerability over an additional period of 52 weeks. Primary outcome was the retention to treatment at week 58; secondary measures related to seizure and adverse event frequency. RESULTS: Of 361 randomized patients, 359 were included (CR-CBZ n = 121, LTG n = 117, LEV n = 122) in the modified intent-to-treat population (mean age [range] 71.4 [60-95] years). At week 58, the retention rate for LEV was significantly higher than for CR-CBZ (61.5% vs. 45.8%, p = 0.02), and similar to LTG (55.6%). Seizure freedom rates at weeks 30 and 58 were not different across the groups. Twice as many patients receiving CR-CBZ discontinued due to adverse events or death compared to those in the LEV group (32.2% vs. 17.2%; odds ratio 2.28, 95% confidence interval [CI] 1.25-4.19, p = 0.007), whereas discontinuation was intermediate for LTG (26.3%). Median daily doses of completers (n = 195) were CR-CBZ 380.0 mg/day (333.0-384.0), LTG 95 mg/day (94.0-97.0), and LEV 950 mg/day (940.0-985.0). SIGNIFICANCE: In the initial monotherapy of focal epilepsy in the elderly, 1-year retention to LEV was higher compared to CR-CBZ due to better tolerability. Retention of LTG was intermediate and close to LEV, but did not differ significantly from either comparators. NCT00438451, www.clinicaltrials.gov.

Dopaminergic modulation of low-Mg²âº-induced epileptiform activity in the intact hippocampus of the newborn mouse in vitro.

To investigate whether epileptiform activity in the immature brain is modulated by dopamine, we examined the effects of dopaminergic agonists and antagonists in an intact in vitro preparation of the isolated corticohippocampal formation of immature (postnatal days 3 and 4) C57/Bl6 mice using field potential recordings from CA3. Epileptiform discharges were induced by a reduction of the extracellular Mg(2+) concentration to 0.2 mM. These experiments revealed that low concentrations of dopamine (<0.3 µM) attenuated epileptiform activity, whereas >3 µM dopamine enhanced epileptiform activity. The D1-agonist SKF38393 (10 µM) had a strong proconvulsive effect, and the D2-like agonist quinpirole (10 µM) mediated a weak anticonvulsive effect. The proconvulsive effect of 10 µM dopamine was completely abolished by the D1-like receptor antagonist SCH39166 (2 µM) or the D2-like antagonist sulpiride (10 µM), whereas the D2 antagonist L-741626 (50 nM) and the D3 antagonist SB-277011-A (0.1 µM) were without effect. The anticonvulsive effect of 0.1 µM dopamine could be suppressed by D1-like, D2, or D3 receptor antagonists. A proconvulsive effect of 10 µM dopamine was also observed when AMPA, NMDA, or GABA(A) receptors were blocked. In summary, these results suggest that 1) dopamine influences epileptiform activity already at early developmental stages; 2) dopamine can bidirectionally influence the excitability; 3) D1-like receptors mediate the proconvulsive effect of high dopamine concentrations, although the pharmacology of the anticonvulsive effect is less clear; and 4) dopamine-induced alterations in GABAergic and glutamatergic systems may contribute to this effect.

Alteration of dopamine D2/D3 receptor binding in patients with juvenile myoclonic epilepsy.

PURPOSE: To quantify extrastriatal and striatal D2/D3 receptor binding in patients with juvenile myoclonic epilepsy (JME) using the high-affinity dopamine D2/D3 receptor positron emission tomography (PET) ligand (18) F-Fallypride ([(18) F]FP). METHODS: Twelve patients with JME and 21 age-matched control subjects were studied. Dynamic images (180 min) were acquired after injection of [(18) F]FP. Patients had been seizure-free of all seizure types for at least 10 days before scanning. Parametric images of binding potential (BP) were created using the simplified reference tissue model. The images were stereotactically normalized using a ligand-specific template. We performed a voxel-based analysis with statistical parametric mapping (SPM2). Region of interest (ROI) analysis was done comparing the BP of the thalamus, caudate nucleus, anterior (ventral) and posterior (dorsal) putamen, ventral striatum, and temporal lobe. RESULTS: Compared to controls, patients with JME showed a significant decrease in [(18) F]FP BP (SPM analysis corr. p < 0.001 at cluster level) restricted to the bilateral posterior putamen. There was no significant alteration of [(18) F]FP binding in other brains regions. ROI analysis revealed a significant (p < 0.05) decrease of [(18) F]FP BP in the left (mean -14.8%) and right (mean -16.9%) posterior putamen, but not in the anterior putamen, caudate, ventral striatum, thalamus, or temporal lobe. DISCUSSION: Patients with JME showed a reduction in D2/3 receptor binding restricted to the bilateral posterior putamen, suggesting a specific alteration of the dopaminergic system. Whether these changes can be regarded as merely functional or whether they relate to the pathophysiology of juvenile myoclonic epilepsy still remains unclear.