Benperidol is a relatively old antipsychotic drug that has been marketed since 1966. It has been used in Germany for 30 years, but is also available in Belgium, Greece, Italy, the Netherlands and the UK. Benperidol is a drug which is a highly potent butyrophenone derivative. It is the most potent neuroleptic on the European market, with chlorpromazine equivalency as high as 75 to 100 (about 150 to 200% potency in terms of dose compared to haloperidol). Benperidol was discovered at Janssen Pharmaceutica in 1961. Benperidol is a potent dopamine receptor antagonist, with a high affinity for the D2-sites. The antipsychotic effects of this drug are primarily due to blockade of the D receptors. In terms of D receptor blockade, benperidol is one of the most potent antipsychotic agents, being approximately eight times more potent than haloperidol. Benperidol also acts as a dopamine antagonist in the chemoreceptor trigger zone, giving rise to antiemetic properties. It is also a weak antagonist at muscarinic, histamine H1, and alpha1-adrenoceptors. Adverse effects include extrapyramidal side effects and tardive dykinesia