Levodopa is the most effective agent for treating the symptoms of Parkinson's disease (PD). However, levodopa-induced dyskinesia remains a significant complication that manifests after few years of treatment, for which therapeutic options remain limited. Several agonists of the serotonin type 1A (5-HT1A) receptor with varying levels of efficacy and interaction at other sites, have been tested in the clinic. Clinical trials testing 5-HT1A agonists have yielded inconsistent results in alleviating dyskinesia, especially that the antidyskinetic benefit observed was often accompanied by an adverse effect on motor function. In this article, we summarize and analyze the various clinical trials performed with 5-HT1A agonists in PD patients with dyskinesia and offer perspectives on the future of this class of agents in PD.
Keywords: 5-HT1A agonists; Parkinson's disease; aripiprazole; befiradol; buspirone; dyskinesia; levodopa; pardoprunox; sarizotan; tandospirone.
After prolonged treatment with levodopa, patients with Parkinson's disease might start to experience abnormal involuntary movements, called ‘dyskinesias’. These abnormal movements may be difficult to cope with since they can occur for several hours during the day and can hamper the quality of life. A potential approach to reduce the severity of dyskinesia, which has been the focus of extensive research, consists of stimulating a target inside the brain called the 5-HT1A receptor. Several drugs harbouring this mechanism of action have been tested in clinical studies. Here, we provide an overview of these clinical studies and discuss their results.