Availability of drug assay results and dosage advice improves antiepileptic care in a specialist neurology outpatient clinic.

The incidence of grand mal seizures, distribution of drug levels relative to the therapeutic range and the incidence of side effects were monitored before and after the provision of same-day preconsultation assay results (phenytoin and carbamazepine) to an epilepsy clinic. A total of 300 patients completed the study. The proportion of patients fitting fell from 23.3% at entry to 10% at review (P less than 0.01) while the incidence of side effects fell from 30.7% to 17.3% (P less than 0.01) and the proportion of phenytoin levels in the therapeutic range rose from 41% to 58% (P less than 0.01). Similar patterns were observed in 111 patients who entered the study during a control observation period. The provision of appropriate support services (assay results and dosage advice) to specialist epilepsy clinics allows improvement in the management of epilepsy.