Acute Manic Relapse with Dexfenfluramine

TO THE EDITOR We read with interest the recent case report by Drs Soon-Jai Kwon et al. on Appetite Suppressor Induced Psychosis in which a case of de novo psychotic symptoms with phentermine use was reported. We had an Asian patient in whom dexfenfluramine, also an amphetamine related, centrally acting appetite suppressant, exacerbated an acute manic relapse. The patient is a 33 year old Asian lady with a BipolarI Disorder first diagnosed at age 22. Her last relapse had been about 3 years previously after she stopped treatment during her second pregnancy. She was well stabilized on Haloperidol 5 mg/day and Lithium 750 mg/day but the medication, lifestyle and dietary habits caused a gradual increase in weight over the years, almost doubling to 115 kg. She was started on Dexfenfluramine by her family physician and continued this for 18 days till her review at the psychiatric outpatient clinic when she was advised to discontinue it immediately. At that time she was noted to be a little talkative, excited and her mood was expansive. Despite stopping Dexfenfluramine, her condition deteriorated and 13 days later she was hospitalised for a relapsed manic state. She was talkative, grandiose, elated and disinhibited. Her sleep was poor and she had been argumentative and demanding at home. There was no history of any significant recent stresses in her life and no history of alcohol or illicit drug use. The hematology and biochemical investigations were normal and the serum lithium was 0.69 mEq/ l on admission. She was admitted for inpatient treatment and her medication was increased to Haloperidol 20 mg/day, Lithium 750 mg/day and Diazepam 20 mg at night. She stabilized after 2 weeks. From the history, the manic relapse in this patient was triggered by the use of Dexfenfluramine. Dexfenfluramine a pure serotonin agonist, activates the serotoninergic system as does its main metabolite nordexfenfluramine. It has also been reported as useful in carbohydrate binge behaviors and other depressive symptoms in some patients with seasonal affective disorder. We agree with Dr Kwon et al about the crucial role of the appetite suppressant in triggering de novo psychiatric illnesses and we share our experience of an exacerbation of a pre-existing psychiatric condition to emphasise the need for caution.