She had unilaterally discontinued her antipsychotic medications 6 to 8 months prior to hospitalization. Her medical history was unremarkable. She did not have a history of congestive heart failure, hepatic disease, nephrosis, hyponatremia, or vascular occlusive disease.

Ms F was initiated on risperidone 1 mg at bedtime. On day 3, she developed 2-plus pitting pedal edema bilaterally up to mid-shin, which was worse on her right leg. All lab work, including IgE, C₃ and C₄, were within normal limits. Her risperidone was discontinued, and her edema resolved in 2 days. She was subsequently placed on Zyprexa (olanzapine) and tolerated its titration well.

Ms F was not on any other medication and, as such, a drug interaction can be ruled out. Given her normal IgE, C₃ and C₄, the edema is unlikely to have been secondary to an allergic reaction. Other reports have alluded to the possibility that edema with risperidone is dose-dependent. In this case, Ms F’s edema occurred at a low dosage.

The etiology of Ms F’s pedal edema remains unclear. Perhaps, as our experience with risperidone expands, the relevance of edema as a side effect will be further elucidated.

References

1. Cooney C, Nagy A. Angio-oedema associated with resperidone [letter]. BMJ 1995;310:1204.

Dear Editor:

Red Bull, a widely consumed “power drink” that is a mixture of 3 key psychoactive ingredients (caffeine, taurine, and inositol), has been shown to positively affect human mental performance and mood. Caffeine seems to exacerbate manic symptoms (1), and heavy caffeine intake appears to contribute to a worsening course of seasonal bipolar disorder (2). Taurine is a sulfur amino acid that has been related to acute psychotic episodes (3). Inositol has been involved in the regulation of cellular responses in neuronal membranes through interactions with various specific proteins on the phosphatidylinositol system. Its clinical administration has been associated with induced mania (4). We report a case of an acute manic episode after this drink’s ingestion.

Case Report

A 36-year-old white man with a DSM-IV diagnosis of bipolar I disorder was admitted

2. Baldassono CF, Ghaemi SN. Generalized edema with resperidone: divalpoex sodium treatment [letter]. Clin Psychiatry 1998;82–3.
3. Sanders RD, Leherer DL. Edema associated with addition of risperidone to valproate treatment [letter]. J Clin Psychiatry 1998;59:989–90.
4. Terao T, ojima H, and others. Risperidone and allergic reactions [letter]. J Clin psychiatry 1998;59:2.

Sajid Ravasia, MD
Fargo, North Dakota

for hospitalization during his second manic episode. He presented with a Young Manic Rating Scale (YMRS) score = 35, despite adequate compliance (lithium = 1.0 Meq/L). For 5 years, he remained without any subclinical mood episodes, and he had been taking daily dosages of lithium 900 mg (0.8 to 1.1 Meq/L). One week before hospitalization, he drank 3 cans of Red Bull at night. He stated that during this night, he experienced a decreased need for sleep. Three days later, he drank 3 more cans. After 4 days, he was feeling euphoric and hyperactive, with insomnia. He gradually became more hyperactive, experiencing increased libido and irritability. Seven days after admission, using only lithium at the usual dosage (lithium = 0.9 Meq/L), YMRS scores decreased to 17. To our knowledge, this is the first report that describes mania associated with the use of “power drinks.” Although anedoctal, this report suggests that the psychostimulant effects of beverages containing caffeine, taurine, and inositol in their formula might be associated with pathological mood switches, even in euthymic patients with bipolar illness. Also, according to Anand (5), the stimulant agent amphetamine led to a significantly greater behavioural response in patients with bipolar illness than in unaffected subjects, possibly due to enhanced postsynaptic dopamine responsivity in patients with bipolar illness. The stimulant effects of caffeine induce changes in motor activity,