Special attention will be given to instruction of patients in dental hygiene and patients showing signs of gingival hyperplasia will be dropped. Studies in epilepsy show that this side effect is surprisingly uncommon, despite wide publicity. No cases were seen in our previous short-term study or prophylactic study (Mishory et al, 2000; Mishory et al, 2003). Nonlinear pharmacokinetics, drug interactions and the consequent danger of toxicity will be handled by careful blood levels monitoring. Patients with significant side effects or toxicity will be dropped from the study. Patients with indications of hypersensitivity reactions (morbilliform rash, Stevens-Johnson syndrome, systemic lupus erythematosus, hepatic necrosis, neutropenia and leukopenia, red-cell aplasia, agranulocytosis, aplastic- or megalo- anemia, or thrombocytopenia) will be dropped from the study.