Bexarotene as add-on to antipsychotic treatment in schizophrenia patients: a pilot open-label trial

Bexarotene is a synthetic retinoid used for treatment of neoplastic or dermatologic disorders. Based on the retinoid dysregulation hypothesis, it was hypothesized that bexarotene augmentation would have a beneficial effect in the antipsychotic treatment of schizophrenia patients. This study is the first to investigate the safety and efficacy of add-on oral bexarotene to ongoing antipsychotic treatment in chronic schizophrenia patients who were stabilized on regular antipsychotic treatment.

A 6-week open label trial was conducted in 2 mental health centers from October 2005 to October 2006. Twenty-five patients with chronic schizophrenia received a low dose of bexarotene (75 mg/d) augmentation. Mental condition and laboratory tests were assessed at baseline and after weeks 2, 4, and 6 of the study. The primary outcome measure was change from baseline in 4 symptom scales: the Positive and Negative Symptom Scale, Extrapyramidal Symptom Rating Scale, Abnormal Involuntary Movement Scale, and Barnes Akathisia Scale. Blood cell count, liver and thyroid functions, cholesterol, and triglyceride rates were followed.

Significant improvement from baseline to endpoint was observed on total Positive and Negative Symptom Scale score (P = 0.022), general psychopathology (P = 0.024), positive (P = 0.012), and the dysphoric mood (P = 0.028) factor scores. Furthermore, a trend to a diminishing Extrapyramidal Symptom Rating Scale score (P = 0.053) was found. Bexarotene was found to be a safe medication as measured by all laboratory parameters with the exception of increased total cholesterol serum level.

This short-term pilot study supports bexarotene as a potential valuable adjunct in management of schizophrenia. Low doses of bexarotene were well tolerated. A double-blind controlled study should be performed to replicate these preliminary positive results.