Neurotransmitter receptor binding studies predict antiemetic efficacy and side effects.

Radioligand binding studies were used to analyze the interaction of antiemetics with central dopamine D2 and alpha-adrenergic1 receptors. The affinity of antiemetics for dopamine D2 receptors labeled by 3H-spiperone significantly correlated with clinically effective drug doses (r = 0.92; P less than 0.01). Furthermore, the relative inhibition of alpha-adrenergic1 receptors as measured by 3H-WB 4101 binding predicts the clinical side effects of sedation and orthostatic hypotension. Neurotransmitter receptor binding analysis provides a rapid and sensitive technique for measuring antiemetic potency as well as associated side effects.