Repurposed drugs for the treatment of schizophrenia and bipolar disorders

Characteristic symptoms of schizophrenia and bipolar disorders have been described and classified about a century ago. Each of these disorders may cause considerable impairment reflecting substantial alterations in cognition, perception, and mood. Though both disease concepts are well established, psychopharmacological treatment strategies, involving first- and second-generation antipsychotics, benzodiazepines and mood stabilizing drugs, often fail to keep their purported alleviating effects on respective characteristic symptom spectra, producing unsatisfactory patient responses. While drug profiles may differ concerning the underlying mechanism of action, the breadth of treatment options remains limited. Besides developing new drugs with different mechanisms of action, side-effect profile and efficacy, it has to be emphasized that repurposed drugs might serve as alternative or adjuvant treatment options for patients, who continue to poorly respond to standard treatment algorithms. Here, we review the current evidence of selected drugs whose repurposed use might expand the range of treatment options for schizophrenia and bipolar disorders.