[The significance of laboratory findings in long-term antiepileptic therapy]

A retrospective study of 316 patients (173 men, 143 women; mean age 39 [17-87] years) who had taken antiepileptics (phenytoin, phenobarbital, carbamazepine, valproic acid) for at least six months, was carried out to assess the biochemical and haematological changes in relation to the drug used, the therapeutic programme and the drug serum levels. The most frequent change was isolated elevation of gamma-GT (9-89% of cases depending on the drug), followed by elevation of alkaline phosphatase (16-44%). Increases in the transaminases GOT (4-13%) and GPT (4-19%) were infrequent and minor. Changes in the blood picture were very infrequent and never more than minimal. Correlation between all these changes and serum drug levels was poor (r less than 0.15). Correlations between drug serum level and dose were found in the case of phenobarbital (r = 0.6) and valproic acid (r = 0.5). There was hence no evidence of any clear connection between the biochemical findings and the serum concentrations of antiepileptic drugs or their-dosage. The results indicate that undue importance has previously been attached to routine checks of biochemical parameters; abnormal biochemical findings by themselves are not usually enough to necessitate changes in treatment. Determination of biochemical and haematological parameters is necessary only if there are clinical grounds for it such as suspicion of side effects, the occurrence of epileptic attacks despite therapy, or change from one drug to another.