Description Added a definition in the ‘other important medical event” category to indicate that suspected transmission of an infectious agent by a medicinal product was considered a serious adverse event. The statistical procedures section was modified to indicate that physical and neurologic examination results were to be analyzed by tabulation of abnormal results, not by change from baseline at each time point. The section on the use of concomitant AEDs was updated to clarify the criteria for inadequate response to prior AEDs, and indicate that participants with a history of 10 or more generalized seizures (of any type) per month must have exhibited inadequate response to at least 3 prior AEDs. Additional clarifications were made to the Prohibitions and Restrictions, and to the Pre-study and Concomitant The Study Protocol was also updated to specify that participant who could tolerate the dosage during the first week of the titration period, or who could not tolerate a dosage reduction during Weeks 2 through 4 as a result of side effects, were to be withdrawn from the study. Finally, the sections on Laboratory Tests, and ECG collection, were clarified to remove serum pregnancy testing (only urine pregnancy tests to be performed). The pregnancy test was added for Visit 3 (Day 1). A second ECG reading was made at visit 3 (baseline). The visit window for Visits X1 to X3 of study was changed from 2 weeks to 3 days. The statistical step-down procedure was modified for both the primary and secondary efficacy endpoints. The step-down procedure was planned to ensure the type I error rate due to multiple treatment comparisons was controlled at the 0.05 level. First, the carisbamate 800-mg/day and 1200 -mg/day dosage groups were be combined as a single group, and the combined carisbamate group compared with the placebo group for the endpoint.

A change was made to specify that participants currently receiving double-blind study medication, or who have been receiving carisbamate in the extension phase for less than 6 weeks, must be withdrawn from the study if they experience during the study, or have a history (at any time in their life) of Stevens Johnson Syndrome, toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms, a drug-related exfoliative rash, any drug-related rash requiring hospitalization, or rash associated with an AED that involved conjunctiva or mucosae, or a maculopapular rash that required discontinuation of an antiepileptic drug [AED]. Finally an amendment was made to specify that enrolled participants who concurrently develop two or more of the following signs and symptoms should be withdrawn from the study, unless these are clearly attributable to another documented illness (e.g.,infectious pneumonia): rash; fever (Less than [>] 38.5ºC); lymphadenopathy (must have either enlargement of nodes relative to baseline, or tenderness); eosinophilia (absolute eosinophil count greater or equal to 700/microliter, or, if elevated at baseline, an increase of more than 50%); alanine aminotransferase [ALT] greater than 2 times the upper limit of normal (ULN), confirmed by a repeat measurement; signs or symptoms of significant pulmonary, cardiac, renal, muscular or pancreatic involvement.