The continual applicability of routine plasma measurement of antiepileptic drugs (AEDS) was assessed in 301 epileptic patients with mean age and body weight+/-SD of 30+/-10.6 years and 55+/-19 kg, respectively. The AEDS used included carbamazepine (CBZ), phenytoin (PHT) or valproic acid (VPA) which were given either alone (monotherapy) or in combination (polytherapy). The incidence of uncontrolled epilepsy was significantly higher (P<0.001) in polytherapy vs monotherapy of AEDS and when plasma levels of the drugs were in the subtherapeutic range (P<0.01 for PHT, and P<0.001 for CBZ). Subtherapeutic levels of CBZ were seen with fixed and reasonable doses of 600 mg of the drug given daily. Also, the concentration dose ratios of AEDS were significantly lower in polytherapy vs monotherapy. In conclusion, routine plasma monitoring of AEDS especially in uncontrolled cases of epilepsy could be considered as a fast tool for proper therapeutic approach and dose optimisation in these psychologically and socially devastating episodes.
Copyright 1999 The Italian Pharmacological Society.