A Case Report of Drug-Induced Dermatitis With Weekly Fluoxetine.

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Sir: The new once-weekly formulation of fluoxetine can potentially enhance compliance with maintenance treatment. Physicians should, however, monitor the occurrence of side effects when switching patients from daily to weekly fluoxetine treatment. We present the case of a female patient with schizophrenia and depression who was switched from daily to weekly fluoxetine treatment twice and developed a full body rash on both occasions. Case report. Ms. A, a 33-year-old white woman with DSM-IV diagnoses of chronic paranoid schizophrenia, depressive disorder not otherwise specified, and mild mental retardation, has been attending a continuing day treatment program. The patient was first hospitalized at age 18 due to auditory hallucinations and delusions of persecution. Since then, she has had multiple psychiatric admissions due to auditory hallucinations and suicide attempts. Her family history was significant for depression and alcoholism in a paternal grandparent. Her medical history was significant for obesity, cystic acne, and allergy to lithium carbonate. Ms. A remained stable until April 2001, when she developed an exacerbation of psychotic symptomatology characterized by an increase in auditory hallucinations and depression requiring inpatient treatment. She was discharged on treatment with olanzapine, 20 mg at bedtime, and fluoxetine, 20 mg daily. At entry into the day treatment program in April 2001, her Brief Psychiatric Rating Scale score was 21 and her Hamilton Rating Scale for Depression score was 5. Eight weeks after her discharge from inpatient treatment, Ms. A was switched from daily fluoxetine treatment to fluoxetine, 90 mg weekly, and continued on treatment with olanzapine, 20 mg at bedtime. Thirteen days later, she developed a full body rash. No other medication changes had been made other than the switch to weekly fluoxetine. The weekly fluoxetine was discontinued, and she was treated with diphenhydramine, 50 mg orally. Due to lack of efficacy and the development of hives in her mouth, her family physician stopped the olanzapine treatment. Diphenhydramine was continued, and prednisone, 30 mg per day for 3 days with a subsequent tapering schedule, was added. Three days after the discontinuation of olanzapine, she developed insomnia, and zolpidem, 10 mg at bedtime, was prescribed. The patient's rash cleared, and olanzapine therapy was subsequently restarted. A dermatology consultation was sought; however, by then the rash had cleared and no new recommendations were made. Two weeks later, treatment with fluoxetine, 20 mg daily, was restarted and was well tolerated with no reappearance of a rash. Two months later, another attempt was made to restart treatment with fluoxetine, 90 mg weekly, after discontinuing daily fluoxetine therapy with the patient's consent. After 1 dose of the weekly fluoxetine, the rash recurred, leading to subsequent discontinuation of the weekly preparation and a return to daily fluoxetine treatment. Ms. A had been maintained for approximately 7 years on daily fluoxetine treatment, but when switched on 2 occasions to the weekly formulation of the same drug, she developed a rash. This suggests a temporal relationship between fluoxetine once-weekly and the rashes. It should be noted that this patient had tolerated daily fluoxetine well for many years, yet developed a rash on treatment with once-weekly fluoxetine. Data from health maintenance organization formulary studies have shown that 6-month treatment completion rates for the selective serotonin reuptake inhibitors fluoxetine, paroxetine, or sertraline were only 22% to 45% in one study1 and 35.8% in another large sample.2 Enteric-coated once-weekly fluoxetine will enhance patient compliance. Once patients feel better on treatment with the antidepressant, the motivation to continue it decreases, with the patient not realizing that depression is a relapsing illness. In such instances, a long-acting preparation such as the once-weekly preparation of fluoxetine should certainly enhance compliance. Once-weekly fluoxetine should be used in patients stable on fluoxetine treatment and should not be prescribed when beginning a course of therapy for depression. Primary care physicians should keep in mind the option of using once-weekly fluoxetine, but should also note that even if patients tolerate daily fluoxetine well, they may still have allergic reactions to the weekly fluoxetine preparation, as this case illustrates. In the clinical trials, diarrhea was seen more often with once-weekly fluoxetine than with placebo (p < .05), and 2 events (nervousness and thinking abnormally) were seen significantly more often (p < .05) with once-weekly fluoxetine compared with daily fluoxetine, 20 mg.3,4 In summary, we think that primary care physicians should use enteric-coated once-weekly fluoxetine in patients who are stable on daily fluoxetine treatment; however, they should also be vigilant in watching for side effects, including allergic reactions, even if daily fluoxetine was well tolerated.