Talipexole dihydrochloride (also known as B-HT920, Domnin, B-HT-920 dihydrochloride) is a novel and potent dopamine D2 receptor agonist, α2-adrenoceptor agonist and 5-HT3 receptor antagonist, which displays anti-parkinsonian activity. Talipexole is marketed as a treatment for Parkinson's Disease in Japan by Boehringer Ingelheim; it was introduced in 1996. As of December 2014 it was not approved for marketing in the US nor in Europe. Talipexole is a D2 dopamine receptor agonist and interacts both pre- and post-synaptic receptors. It also is an α2-adrenergic agonist. The main side effects are drowsiness, dizziness, hallucinations and minor gastrointestinal complaints. In 2008 the Japanese Ministry of Health, Labour, and Welfare mandated that Boehringer add a warning to the label concerning the risk of sudden onset of sleep.