Abstracts

Rationale: Long term observational data on antiepileptic drugs (AEDs) inform about their use in clinical practice. We describe our clinical experience with PER in a large tertiary epilepsy centre in UK. Methods: Adults with epilepsy initiated on PER at an UK tertiary referral centre (National Hospital for Neurology and Neurosurgery) between October 2012 and March 2015 were identified from clinical databases. Data on syndrome, duration, seizure types, concomitant and previous AED use, PER dosing, efficacy, side effects and retention were extracted from e-records. Efficacy was categorized as temporary or ongoing (at last follow up) seizure freedom of >3 times the longest pre-PER 12 months seizure interval, >50% of seizure reduction, or other marked benefit (e. g. cessation of convulsions or daytime seizures). Categories were mutually exclusive except for those with temporary seizure freedom. Data were censored at last follow up prior to Sept 11, 2016 using Microsoft Excel and XLSTAT. Data are given as range (Interquartile range) where applicable. Results: 391 adults (58.5% women) received a prescription for PER. Five people never took the drug, and no follow up data after initiation were available for ten. 55% had symptomatic focal epilepsy, 33% cryptogenic focal epilepsy, and 12% generalised or undefined epilepsy. Psychiatric comorbidities were identified in 26% and learning disability in 17%. People were prescribed PER in addition to 1-7 (2, 2, 3) AEDs and had documented previous use of 0-18 (5, 7, 10) further AEDs. People attained a dose of 1-14 (6, 8, 10) mg. Estimated retention rates were 60.4% at one year, 46.9% at 2 years, and 39.9% at 3 years, similar to our historic cohort of Lacosamide (Novy J et al, Epilepsy Research 2013 106:250-6). Of 376 people in the cohort, 36 (9.6%) had periods of seizure freedom, temporary in 25 for 1-19 (2, 4, 8.5) months, and ongoing at last follow up in 11 for 6-38 (11, 18, 29) months. A >50% reduction in seizure frequency was reported by 89 people (23.7%), temporary in 43 for 1-36 (11, 18, 29) months, ongoing in 46 for 5-42 (18, 27, 32.5) months. A marked improvement was seen in 57 people (15.2%), temporary in 17 for 1-33 (83.5, 12, 15) months, ongoing in 40 for 6-41 (17, 24, 33) months. Five (1.3%) discontinued their other AEDs and achieved monotherapy for 4-27 months. Somatic side effects were reported by 197 people (52.4%), mostly affecting the CNS (drowsiness, dizziness, unsteadiness). Mood changes, irritability or challenging behaviour were reported by 137 people (36.4%). PER was stopped by 211 people (56%) due to side effects (39%), inefficacy (26%), or both (35%).  There were no idiosyncratic adverse events. Conclusions: Perampanel was associated with good efficacy, safety and tolerability and resulted in temporary or ongoing benefit in nearly half of people in this cohort with highly refractory epilepsy. Funding: UCL DCEE receives institutional funding from the UK National Institute of Health Research.