Faculty Bibliography

PURPOSE: To evaluate the impact of enzyme-inducing antiepileptic drugs (EI-AEDs) on serum antiretroviral (ARV) levels in patients with HIV. METHODS: Data from the U.S. Military HIV Natural History Study were screened to identify participants taking ARVs with EI-AEDs and controls taking ARVs with non enzyme-inducing AEDs (NEI-AEDs). The proportion of serum ARV levels below the recommended minimum concentrations (C(min)) was compared between these groups. RESULTS: ARV levels were available for 10 individuals exposed to 16 intervals on combined ARVs/EI-AEDs (phenytoin and carbamazepine) and for 25 controls exposed to 30 overlap intervals on combined ARVs/NEI-AEDs. The percentage of overlap intervals with >/=1 ARV levels below C(min) was higher in the EI-AED group than in controls (37.5% vs. 23.3%; p=0.124). After excluding intervals associated with serum levels of EI-AEDs below the reference range (n=6), the proportion of intervals with >/=1 ARV level below C(min) was significantly greater among EI-AED recipients (60%) compared to controls (23.3%; p=0.008). CONCLUSIONS: ARV levels below C(min) were more common in participants receiving EI-AEDs, the difference being statistically significant for intervals associated with EI-AED levels within the reference range. These data suggest that, in agreement with current guidelines, EI-AEDs should be avoided in patients receiving ARV therapy.

OBJECTIVE: To measure the volume of basal forebrain septal nuclei in patients with temporal lobe epilepsy (TLE) as compared to patients with extratemporal epilepsy and controls. In animal models of TLE, septal lesions facilitate epileptogenesis, while septal stimulation is antiepileptic. METHOD: Subjects were recruited from 2 sites and consisted of patients with pharmacoresistant focal epilepsy (20 with TLE and mesial temporal sclerosis [MTS], 24 with TLE without MTS, 23 with extratemporal epilepsy) and 114 controls. Septal volume was measured using high-resolution MRI in association with newly developed probabilistic septal nuclei maps. Septal volume was compared between subject groups while controlling for relevant factors. RESULTS: Patients with TLE without MTS had significantly larger septal nuclei than patients with extratemporal epilepsy and controls. This was not true for patients with MTS. These results are interpreted with reference to prior studies demonstrating expansion of the septo-hippocampal cholinergic system in animal models of TLE and human TLE surgical specimens. CONCLUSION: Septal nuclei are enlarged in patients with TLE without MTS. Further investigation of septal nuclei and antiepileptic septo-hippocampal neurocircuitry could be relevant to development of new therapeutic interventions such as septal stimulation for refractory TLE.

Purpose: To assess the efficacy and safety of once-daily doses of perampanel 8 and 12 mg when added to 1-3 concomitantly administered, approved antiepileptic drugs (AEDs) in patients with uncontrolled partial-onset seizures. Methods: Study 305 was a multicenter, double-blind, placebo-controlled trial in patients aged 12 years and older with ongoing seizures despite prior therapy with at least two AEDs, and currently receiving 1-3 AEDs. Equal randomization to once-daily oral perampanel 8 or 12 mg, or placebo was performed. Patients entered a 19-week double-blind treatment phase comprising a 6-week titration period, with weekly 2-mg dose increments, followed by a 13-week maintenance period. Primary efficacy end points were the responder rate (proportion of patients who had a >/=50% reduction in seizure frequency during treatment per 28 days relative to baseline), and the percent change in seizure frequency per 28 days relative to pre-perampanel baseline. A secondary end point was percent change in the frequency of complex partial plus secondarily generalized seizures. Adverse events (AEs) were monitored throughout the study. Key Findings: Three hundred eighty-six patients were randomized and treated with study medication. Of these, 321 patients completed the study. The 50% responder rates (intent-to-treat analysis) were 14.7%, 33.3%, and 33.9%, respectively, for placebo, perampanel 8 mg, and perampanel 12 mg, with significant improvements over placebo for both perampanel 8 mg (p = 0.002) and 12 mg (p < 0.001). The median percent change from baseline in seizure frequency per 28 days (intent-to-treat analysis) was -9.7%, -30.5%, and -17.6% for placebo, 8 mg, and 12 mg, respectively, with significant reductions compared with placebo for both 8 mg (p < 0.001) and 12 mg (p = 0.011). For complex partial seizures plus partial seizures that secondarily generalized, the median percent change in frequency was -32.7% (8 mg), -21.9 (12 mg), and -8.1% (placebo), with significant reductions for both 8 mg (p < 0.001) and 12 mg (p = 0.005). The most frequent (occurring in >/=10% of patients in any treatment group) treatment-emergent AEs were dizziness, somnolence, fatigue, and headache, with an apparent dose effect suggested for all except headache. Significance: This phase III trial demonstrated that adjunctive treatment with once-daily perampanel at 8 mg and 12 mg was effective in improving seizure control in patients 12 years and older with refractory partial-onset seizures. These study results also demonstrated that once-daily doses of 8 mg and 12 mg were safe and acceptably tolerated in this study. Perampanel demonstrated a favorable risk/benefit ratio in this population.

BACKGROUND AND PURPOSE: Evidence from animal models and examination of human epilepsy surgery specimens indicates that inflammation plays an important role in epilepsy. Positron emission tomography (PET) using [C11]PK11195, a marker of activated microglia, provides a means to visualize neuroinflammation in vivo in humans. We hypothesize that in patients with active epilepsy, [C11]PK11195 PET (PK-PET) may be able to identify areas of focally increased inflammation corresponding to the seizure onset zone. METHODS: A young woman with intractable epilepsy underwent PK-PET as part of an approved research study. PK-PET results were compared with results from other clinical studies. RESULTS: PK-PET revealed an area of focally increased radiotracer uptake in the right frontal lobe corresponding to this patient's seizure focus as identified by ictal and interictal 18F-fluorodeoxyglucose (FDG)-PET and EEG. Routine brain magnetic resonance imaging (MRI) was initially considered normal, though high-resolution studies showed possible subtle dysplasia of the right frontal lobe. The patient underwent a right frontal lobe resection, and pathological evaluation showed focal cortical dysplasia with activated microglia. CONCLUSIONS: PK-PET can identify neuroinflammation associated with subtle focal cortical dysplasia, and may therefore have a clinical role in guiding epilepsy surgery for patients with difficult-to-localize seizure foci. J Neuroimaging 2011;XX:1-3

Clinical trials as part of antiepileptic drug development are increasingly expensive and complex, with many pitfalls that can derail even promising drugs and devices. Although a third of patients remain resistant to treatment, the availability of more than 20 approved antiepileptic drugs can reduce the incentive to enrol in trials of unproven agents, for which safety is not assured. The challenge of recruiting patients drives investigators to regions of the world where treatment options are more limited. This increases complexity and has potential implications for quality of the trial data. Furthermore, the availability of so many approved treatments raises questions about the ethics and safety of placebo-controlled trials in patients with epilepsy. Novel trial designs, such as time-to-event adjunctive therapy and historical-control monotherapy, might be more acceptable to patients and their doctors because they restrict exposure to placebo or ineffective treatments.