Audit of phenytoin prescribing for outpatients

Phenytoin prescribing for outpatients was audited to determine if it had any deficiencies and to identify the incidence of toxicity. A pharmacy audit committee developed process and outcome criteria for phenytoin prescribing. The retrospective audit involved 45 patients (age, 14-72 years) who had regular contact with a seizure clinic for a two-year period. Only one unjustified therapeutic variation existed according to the criteria outlined for the audit. The incidence of phenytoin toxicity was approximately 38%, but all of the patients received acceptable clinical management.