Drug Interaction Between Ascorbic Acid and Fluphenazine

To the Editor.—A number of animal studies have shown that ascorbic acid deficiency results in decreased metabolism of a variety of pharmacologic agents and that the resulting decreased drug enzyme activities can be restored to normal levels if the scorbutic animals are given the vitamin for a period of six to ten days.1 We report a possible drug-drug interaction between ascorbic acid and fluphenazine hydrochloride in a manicdepressive patient who was found on admission to have a low ascorbic acid plasma level. During the 13 days he received replacement ascorbic acid, steady-state fluphenazine plasma levels declined 25% from baseline. This reduction was associated with escalation of manic behavior, which necessitated an increase in fluphenazine and initiation of lithium carbonate treatment.Report of a Case.—The patient was a 23-year-old man who had a past history of manic behavior that was responsive to lithium carbonate. He was admitted to