This article summarizes methodological changes in antiepileptic drug trials and associated advances in knowledge starting from 1938, the year phenytoin was introduced and also the year when evidence of safety was made a requirement for the marketing of medicines in the United States.
The first period (1938-1969) saw the introduction of over 20 new drugs for epilepsy, many of which did not withstand the test of time. Only few well controlled trials were completed in that period and trial designs were generally suboptimal due to methodological constraints.
The intermediate period (1970-1988) did not see the introduction of any major new medication, but important therapeutic advances took place due to improved understanding of the properties of available drugs. The value of therapeutic drug monitoring and monotherapy were recognized during the intermediate period, which also saw major improvements in trial methodology.
The last period (1989-2019) was dominated by the introduction of second-generation drugs, and further evolution in the design of monotherapy and adjunctive-therapy trials.