Active noncompliance as a cause of uncontrolled seizures.

A 26-year-old woman with intractable seizures and fluctuating plasma phenytoin concentrations is described. Noncompliance with prescribed drug regimens was suspected. Phenytoin was first given as a capsule and then as an elixir. Ingestion of the capsule was monitored, and active non-compliance was proved and admitted by the patient. The causes of inadequate plasma phenytoin concentrations are few and can be determined either by specific laboratory methods or by changing the form of the drug.