Abstract
The bioavailability of a phenytoin granule preparation (“Granule”) was studied in 58 epileptic children, and compared to that of other three phenytoin preparations (“Tablet”, “Powder” and “Powderized Tablet”) under a crossover design.
The S/D ratio of “Granule” was about 1.0 for each age group from 5 to 9 years, and about 1.5 for each age group from 10 to 16 years, with the dosis of 5 mg/kg/day. The difference between two age groups was statistically significant.
The S/D ratios of “Powderized Tablet”, “Tablet” and “Granule” were approximately the same and deli-nitely higher than that of “Powder”. Good correlation was found between the dissolution rate determined in vitro by the paddle method of Japanese Pharmacopoeia and in the S/D ratio in vivo.
The particle size measured by the sieving method suggested that a slightly large particlesize of “Powder” was responsible for its low bioavailability. However, many other factors including wettability, crystal forms, etc, seem to affect the difference of bioavailability considerably.
