SCH 39166, a potential antipsychotic drug, does not evoke movement disorders in cebus monkeys.

Subchronic administration of a neuroleptic in cebus monkeys can reliably mimic the abnormal movements produced by these drugs in humans. SCH 39166 is the best candidate to test in this model to determine if selective antagonism at the dopamine D1 receptor is devoid of these side effects. It has superior selectivity for the dopamine D1 site versus several other sites and a significantly longer duration in primates than the prototypical D1 antagonist, SCH 23390. In contrast to haloperidol, weekly administration of SCH 39166 for 14 weeks did not produce abnormal movements but did produce equivalent sedative effects. Thus dopamine D1 antagonists are uniquely different from D2 antagonists with regards to the production of abnormal movements.