Abstract
Two preparations of Phenytoin PHT, PHT Na (mean particle size 260μ) and free PHT (mean particle size 24μ) were administered to nineteen epileptic patients.
Serum levels of PHT were measured gaschromatographically by the Solow method.
In fifteen patients, free PHT was given orally for a twoweekperiod and then PHT Na of the same dose was given for another twoperiod after an interval of two weeks without medication. The mean values of the serum levels on 9th, 11th and 13th day of each respective period were calculated, and then compared in each patient.
In one patient, PHT Na was initially administered for a week and then, the preparation were changed to free PHT. In this case, the mean values of the serum levels obtained on 5th, 6th and 7th days, 10th, 14th and 21th days after the initial administration were compared.
In three other patients already on free PHT, PHT Na was started after PHT serum levels were measured three times.In these cases, serum levels of PHT were measured at least five days after PHT Na administration was started.
A significant increase in the serum levels of PHT following PHT Na administration was found in only two out of nineteen cases. However, four cases showed a significant decrease of PHT serum levels.
These data suggest that the sodium salt of PHT is not superior in bioavailability than the free PHT.
This result is differnt from those in the previous reports. This fact may be attributed to the particle size of PHT Na which is larger than the size of PHT Na reported in the foreign literature.
