The primary objective was to investigate whether multiple-dose administration of eslicarbazepine acetate affects the pharmacokinetics of metformin.

Inclusion Criteria:

• Male or female subjects aged between 18 and 45 years, inclusive.
• Body mass index (BMI) between 19 and 30 kg/m2, inclusive.
• Healthy as determined by pre-study medical history, physical examination, vital signs, complete neurological examination and 12-lead ECG.
• Negative tests for HBsAg, anti-HCVAb and HIV-1 and HIV-2 Ab at screening
• Clinical laboratory test results clinically acceptable at screening and admission to each treatment period.
• Negative screen for alcohol and drugs of abuse at screening and admission to each treatment period.
• Non-smokers or who smoke ≤ 10 cigarettes or equivalent per day.
• Able and willing to give written informed consent.
• (If female) Not of childbearing potential by reason of surgery or, if of childbearing potential, she used one of the following methods of contraception: double barrier or intrauterine device.
• (If female) Negative urine pregnancy test at screening and admission to each treatment period.

Exclusion Criteria:

• Clinically relevant history or presence of respiratory, gastrointestinal, renal, hepatic, haematological, lymphatic, neurological, cardiovascular, psychiatric, musculoskeletal, genitourinary, immunological, dermatological, endocrine, connective tissue diseases or disorders.
• Clinically relevant surgical history.
• History of relevant atopy or drug hypersensitivity.
• History of alcoholism or drug abuse.
• Consumed more than 14 units of alcohol a week.
• Significant infection or known inflammatory process at screening or admission to each treatment period.
• Acute gastrointestinal symptoms (e.g., nausea, vomiting, diarrhoea, heartburn) at the time of screening or admission to each treatment period.
• Used medicines within 2 weeks of admission to first period that may affect the safety or other study assessments, in the investigator's opinion.
• Used any investigational drug or participated in any clinical trial within 6 months prior to screening.
• Participated in more than 2 clinical trials within the 12 months prior to screening.
• Donated or received any blood or blood products within the 3 months prior to screening.
• Vegetarians, vegans or with medical dietary restrictions.
• Could not communicate reliably with the investigator.
• Unlikely to co-operate with the requirements of the study.
• Unwilling or unable to give written informed consent.
• (If female) Pregnant or breast-feeding.
• (If female) Of childbearing potential and she did not use an approved effective contraceptive method (double-barrier or intra-uterine device) or she used oral contraceptives.