- Currently managed on a stable treatment regimen (including diet), which may include low-fat/high-carbohydrate diet, avoidance of fasting, carnitine and/or medium-chain triglyceride (MCT) oil. The treatment regimen (including diet) should be stable for the last 60 days to assure that changes in the subject's condition are not confounded by recent changes in the treatment regimen that could affect the 4 week run-in evaluation period. Once study drug treatment has started, must be willing to maintain all aspects of the subject's treatment regimen and diet unchanged, other than discontinuation of MCT oil, in order to avoid potential variability of response due to variations in dietary intake.