AN AUDIT OF THERAPEUTIC DRUG-MONITORING OF ANTICONVULSANTS

An audit of therapeutic drug monitoring (TDM) of anticonvulsants was p erformed to assess both its use and misuse in the management of patien ts with epilepsy, Over a four week period all samples received for phe nytoin, carbamazepine, sodium valproate and phenobarbitone assays were included in the audit The aims were to establish the source of the sp ecimens, the reasons for rite requests and to ascertain what action, i f any, would be taken when the result of the assay was provided. A tot al of 163 separate assays were performed over the four week period (43 phenytoin, 74 carbamazepine, 41 valproate, 5 phenobarbitone). Only 18 .7% of all requests originated from the adult neurology department. Th e vast majority of tests had been ordered by junior medical staff (onl y 10% by consultants) and approximately 50% were 'routine' with no sat isfactory clinical reason for the request offered There was a tendency to manipulate prescribed doses on the basis of drug levels alone with out taking the clinical picture into consideration. These results demo nstrate a general ignorance, especially amongst junior medical staff o f the value of TDM of anticonvulsants, and reinforce the need for both an educative and interpretive service to be provided by the Chemical Pathology Department.