Phenytoin changed epilepsy treatment because it showed that an antiseizure medicine did not have to work mainly by making people sleepy. Houston Merritt and Tracy Putnam identified its anticonvulsant properties in the 1930s, with clinical efficacy established before the drug entered use in 1938.
A different way to search for treatment
Earlier discoveries such as bromides and phenobarbital had been important, but sedation was closely tied to their use. Merritt and Putnam used experimental seizure models to screen compounds specifically for anticonvulsant activity. Phenytoin stood out because it could suppress seizures without being primarily hypnotic.
Why 1938 mattered
The introduction of phenytoin helped establish systematic drug discovery in epilepsy. It became a major treatment for focal and tonic-clonic seizures and influenced later programmes that screened compounds for antiseizure effects.
Not a perfect medicine
Its historical importance should not be confused with modern first-choice use for everyone. Phenytoin has important interactions, dose-related toxicity and long-term adverse effects. Its significance here is historical: it demonstrated that seizure suppression and sedation could be separated.
Sources
Discovery of phenytoin
Antiepileptic drug therapy: the story so far
Phenytoin: 80 years young