Abstract
We retrospectively examined the effects of the combination of zonisamide (ZNS) on the serum valproate (VPA) concentrations in 10 epileptic patients. The serum VPA concentrations at a steady state in VPA and ZNS combination therapy was about 1.1 times as high as those in VPA monotherapy (p<0.01). Furthermore, the extent of change in the VPA concentrations ((VPA concentration in the combination therapy of VPA and ZNS) / (VPA concentration in the VPA monotherapy)) tended to increase in proportion to the serum concentration of ZNS. These results suggest that the pharmacokinetic interaction between these drugs may be clinically negligible, however the serum VPA concentrations should be carefully monitored when the serum ZNS concentration is high.
