Serum phenytoin levels with different brands.

Four brands of phenytoin were studied in 60 newly diagnosed epileptic patients randomly and equally placed in 4 groups. Serum phenytoin levels were estimated by EMIT and spectrophotometric methods both of which gave close values with good correlation (r = 0.985). Average serum levels and the incidence of remission achieved with the 4 brands varied within statistical scatter; thus these 4 brands manifested equivalent therapeutic efficacy. In 22 patients serum level was less than 5 micrograms/ml, in 9 of whom attacks remained uncontrolled. In 38 patients serum level exceeded 5 micrograms/ml in 2 of whom attacks were uncontrolled. In 44 out of 60 patients the 2 weeks serum levels were significantly higher (P less than 0.001 by paired t-test) than those after 3 months. In the remaining 16 patients the serum levels at 3 months were significantly higher than at 2 weeks levels (P less than 0.01).