This was a multinational, randomised, double-blind, placebo-controlled, parallel-group study to evaluate the efficacy, safety, and tolerability of multiple doses of ESL as prophylactic treatment in subjects with migraine with or without aura. Subjects were randomised in a 1:1:1 ratio to receive placebo, ESL 800 mg/day once daily (QD), or ESL 1200 mg/day QD.

The study consisted of a Screening Period of 2 to 4 weeks, a 4-week placebo Baseline Period, a 2-week Titration Period, a 12-week Maintenance Period, and a 4-week Follow-up Period. During the entire study the subjects had a diary to document the occurrence, duration, and intensity of headaches, the occurrence or not of aura and its nature, as well as other related symptoms, and the use of study medication and acute medication.

Inclusion Criteria:

• Women or men, 18 years of age or older (according to Amendment #1 for Czech Republic [24 Mar 2009]: 18 to 65 years of age).
• Diagnosis (established prior to 50 years of age) of migraine headaches for at least 1 year, and a well-documented history of migraine headaches with or without aura according to the criteria of the IHS (see Section 3.5.6.1) for at least 3 months (according to Amendment #1 for Czech Republic [24 Mar 2009]: for at least 3 months with at least 3 migraine attacks per month in each of these 3 months).
• At least 2 (according to Amendment #1 for Czech Republic [24 Mar 2009]: at least 3) (and no more than 10) well-defined migraine headache attacks per month, with at least 24 h of freedom from headaches and other symptoms of migraine between attacks.
• Able to distinguish the migraine headache attacks from other types of common headaches (tension-type headaches, sinus-related headaches, etc.).
• Not taking any prophylactic migraine therapies for at least 2 weeks prior to Baseline Visit (V2). Flunarizine had to be discontinued at least 4 weeks prior to V2.
• Able and willing to provide written informed consent to participate in the study after having the opportunity to review the Subject Information Sheet and Informed Consent Form (ICF).
• Able and willing to comply with all study requirements, in the judgment of the investigator.
• Women were surgically sterile (i.e. bilateral tubal ligation, bilateral oophorectomy, or hysterectomy), or at least 2 years postmenopausal or, if of childbearing potential, were sexually abstinent or agreed to use medically acceptable non-hormonal methods of contraception (see Section 3.3.3). (According to Amendment #1 for Czech Republic [24 Mar 2009]: Women were sexually abstinent or agreed to use a double-barrier method of contraception. Hormonal contraceptives were not acceptable as a contraceptive method in this study. However, their intake was not forbidden throughout the study.)

Exclusion Criteria:

• A known hypersensitivity to ESL or to other carboxamide derivatives (e.g. oxcarbazepine, carbamazepine), or to any of the excipients.
• Suspected or confirmed medication-overuse headache.
• More than 14 headache days (migraine or other headache types) per month in either of the 2 months prior to screening.
• Consistent or recurrent frequent headaches (i.e. ≥6 headache days a month) other than migraine headaches.
• Unable to discontinue medications primarily used for migraine prophylaxis that have been commonly used for other indications (tricyclic agents, divalproic acid, topiramate, etc.). A subject who received beta blockers or calcium channel blocker therapy for reasons other than migraine prophylaxis was eligible for inclusion, provided his/her dosing regimen had been stable for ≥2 months and was not expected to change during the course of the study.
• Using prohibited concomitant medication (see Section 3.5.5.2).
• A white blood cell (WBC) count <2.5 * 109/L, neutrophil count <1.5 * 109/L, sodium <125 mmol/L, or alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≥2 times the upper limit of normal at V1 (Screening Visit), or any other clinically relevant laboratory abnormality that, in the investigator's opinion, could compromise the subject's safety.
• A creatinine clearance lower than 60 mL/min at screening.
• A second- or third-degree atrioventricular blockade not corrected with a pacemaker or any other clinically significant abnormality in the 12-lead electrocardiogram (ECG) as determined by the investigator.
• Pregnant or nursing women.
• A history of chronic alcohol or drug abuse or addiction within the last 2 years.
• A severe hepatic, renal, respiratory, haematological, or immunologic illness, unstable cardiovascular disease, or any other medical or psychiatric condition that, in the judgment of the investigator, made the subject inappropriate for entry into this study.
• Received an investigational drug (or a medical device) within 3 months of screening or was currently participating in another study of an investigational drug (or medical device).
• An employee of the investigator or study centre, with direct involvement in the proposed study or other studies under the direction of that investigator or study centre, or was a family member of the employees or the investigator.

Treatment-emergent adverse events(TEAEs) were evaluated throughout the study TEAEs, i.e. those Adverse Events (AEs) starting after the first dose intake until 28 days after the last dose, have been summarised by SOC and PT