Antiepileptic drug levels and side effects in man

It was found in 22 hospitalized epileptic patients taking DPH, primidone, and phenobarbital as a combined therapy that the number of side effects per patient could be correlated only with the serum levels of DPH. In the case of clinial manifestation of side effects it might be concluded that the dosage of DPH should be reduced. One of our patients was treated in this manner resulting in a reduction of the side effects, whereas the frequency of seizures increased. But we succeeded in reducing this frequency by phenobarbital and side effects completely disappeared. If there are any side effects, then, according to our results, it seems to be better to add phenobarbital in order to decrease the DPH serum level instead of reducing DPH dosage. It is, however, known that by phenobarbital the DPH level in patients need not necessarily decrease.