the phenobarbital/primidone plasma concentration ratio is with 4.2 +/- 0.7 ( +/- s.e . ) significantly ( p less than 0.001 ) higher in patients receiving primidone and phenytoin as compared to those on primidone alone ( 1.6 +/- 0.2 ) or together with ethosuximide ( 1.4 +/- 0.7 ) .
C0031412
phenobarbital
C0033148
primidone