Abstract
The effect of combined drugs (i. e. valproate, phenytoin) on serum levels of primidone (PRM) and phenobarbital (PB) derived from PRM and on the ratios of their serum levels to PRM dose (L/ D) were retrospectively evaluated in 37 epileptic patients. The L/D of derived PB and the PB/ PRM in serum levels were higher in patients taking PRM in both the combination with phenytoin (PHT) and with sodium valproate (VPA) compared to those taking PRM with other anticonvulsants. It was also demonstrated that the L/ D of PB and the PB/ PRM were affected by aging. The PB/ PRM in serum were significantly increased in group II (10≤X<20), III (20 ≤X<30) thangroup I (X<10).Furthermore, seasonalvariationsof the PB/PRM in 8 epileptic patients were evaluated. As a result, the PB/PRM in group A (during the period of April to September) were increased significantly (p<0.01), compared to that in group B (during the period of October to March).
