 During the 1920s and 1930s , when the only anticonvulsant drugs were the sedative bromides ( discovered 1857 ) and phenobarbital ( 1912 ) , the ketogenic diet was widely used and studied . This changed in 1938 when H. Houston Merritt and Tracy Putnam discovered phenytoin ( <unk> ) , and the focus of research shifted to discovering new drugs . With the introduction of sodium valproate in the 1970s , drugs were available to neurologists that were effective across a broad range of epileptic syndromes and seizure types . The use of the ketogenic diet , by this time restricted to difficult cases such as Lennox – Gastaut syndrome , declined further . 
