Patients from both sexes, 18 to 65 years of age, diagnosed with simple or complex partial onset epileptic crisis defined according to the International League Against Epilepsy (ILAE) criteria, with a minimum of two seizures within the 4 previous weeks, a stable treatment with two antiepileptic drugs for at least 12 weeks, and capable and willing to give their informed consent, will be included in the study.
To these patients, physicians will prescribe zonisamide in the following manner: Titration period of 12 weeks, at the end of which all patients must be taking 300 mg. Maintenance doses period of 12 weeks, at the beginning of which, physicians will decide to keep the 300 mg dose from the titration period, lower it to 200 mg, or take it up to 400 mg. Six weeks later within this period, a decision will be made to raise the 400 mg doses up to 500 mg if considered necessary and tolerable.
Drugs will be prescribed by the physician and purchased by the patient.