Bio-availability and dissolution of three phenytoin preparations for children.

A study of bio-availability of three drug companies' brands of phenytoin preparations (50mg capsule/tablets) was undertaken on 30 children with tonic-clonic or complex partial seizures. Eight children were excluded because of non-compliance and three because of abnormally high serum levels. Phenytoin capsules (Parke Davis) and tablets (Boots) produced significantly higher serum-level profiles than phenytoin tablets (Evans). Seizure frequencies did not differ significantly with the three brands of phenytoin. Dissolution of the three preparations tested in vitro was different. As a result of this study the authors recommend that children remain on the same manufacturer's brand of phenytoin throughout their treatment.