We evaluated 10 years of post-marketing surveillance (PMS) safety data of ESL in adults and compared it with clinical trials (CTs) adult’s safety data.

PMS data from adult patients (18 to 65 years old) were retrieved from October 1^st, 2009 to September 30^th, 2019. Data were also collected from randomised CTs in adults: BIA-2093-201, -301, -302 -303, -304 and -311. Adverse events (AEs) were coded according to the MedDRA terminology and assessed by causality and seriousness.

3044 AEs were reported for adult patients in PMS (estimated cumulative exposure, 4 179 326 patients-months), 998 (32.8%) serious and 2442 (80.2%) related to ESL. A total of 9764 AEs was reported in CTs (more than 5500 patients exposed), 275 (2.8%) serious and 4542 (46.5%) related to ESL.

From PMS, System Organ Class (SOC), Nervous System Disorders, was the most representative (n=750; 24.6%), followed by General Disorders and Administration Site Conditions (n=383; 12.6%), and Injury, Poisoning and Procedural Complications (n=336; 11%). Most common AEs were ‘hyponatraemia’ (n=215; 7.1%), ‘seizure’ (n=191; 6.3%) and ‘dizziness’ (n=112; 3.7%); these were also the most frequent ESL-related AEs (Adverse Drug Reactions [ADR]) (135 [5.5%], 112 [4.6%] and 108 [4.4%], respectively). Frequently reported serious ADRs were ‘seizure’ (n=180; 19.0%), ‘hyponatraemia’ (n=157; 15.7%) and ‘generalised tonic-clonic seizure’ (n=25; 2.5%).

From CTs, the most common SOC was Nervous System Disorders (n=3084; 31.6%), Gastrointestinal Disorders (n=1292; 13.2%) and Infections and Infestations (n=847; 8.7%). Frequently related AEs were ‘dizziness’ (n=767; 16.9%), ‘somnolence’ (n=387; 8.5%) and ‘headache’ (n=284; 6.3%). Most common serious ADRs were ‘convulsion’ (n=15; 5.5%), ‘ataxia’ (n=13; 4.7%) and ‘vomiting’ (n=10; 3.6%).

With an estimated ten-year cumulative exposure of more than 4 million patients-months worldwide, ESL post-marketing safety data reinforced the positive benefit-risk evidenced in clinical trial setting.