Eligibility Criteria:
Inclusion Criteria:
* Male and female subjects aged 18 to 45 years, inclusive
* Body mass index (BMI) between 18 and 30 kg/m2, inclusive
* Healthy as determined by pre-study medical history, physical examination, vital signs, 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 ex-smokers
* Able and willing to give written informed consent;
* If female, not of childbearing potential by reason of surgery or, if of childbearing potential, she uses one of the following methods of contraception: double barrier method: 1 male barrier method \[male condom\] plus 1 female barrier method (diaphragm, spermicide, or intrauterine device);
* If female, has a 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 any drug hypersensitivity (including known hypersensitivity to ESL or other carboxamide derivatives, simvastatin or other statins or any of its excipients
* History of fibromyalgia, myopathy, rhabdomyolysis or unexplained muscle pain
* 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
* History of alcoholism or drug abuse
* Consume more than 14 units of alcohol a week
* Significant infection or known inflammatory process on 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
* Use of medicines within two weeks of admission to first period that may affect the safety or other study assessments, in the investigator's opinion
* Have donated or received any blood or blood products within the 3 months prior to screening
* Vegetarians, vegans or have other medical dietary restrictions
* Cannot 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, is pregnant or breast-feeding
* If female, is of childbearing potential and does not use an approved effective contraceptive method (double-barrier method: 1 male barrier method \[male condom\] plus 1 female barrier method (diaphragm, spermicide, or intra-uterine device) or uses hormonal contraceptives
* Have received an investigational drug within 3 months of screening or is currently participating in another study