Dopamine receptor antagonists, also known as antipsychotic agents, are critical in managing chemotherapy-induced vomiting. These antiemetic agents block dopamine receptors in the chemoreceptor trigger zone (CTZ), inhibiting signal transmission to the vomiting center. Antipsychotic agents encompass phenothiazines (PTZ), butyrophenones, benzamides, and thienobenzodiazepines (Zyprexa), which are utilized for their antiemetic and sedative properties.

Phenothiazines, such as prochlorperazine (Compazine), are effective against low or moderately emetogenic chemotherapy regimens. Metoclopramide, a substituted benzamide, demonstrates antiemetic activity and enhances gastric motility. This dual functionality makes metoclopramide a versatile therapeutic option. Trimethobenzamide, another substituted benzamide, exhibits antiemetic action via dopamine-receptor blockade and has weak antihistaminic activity, further expanding the spectrum of antiemetic options. Butyrophenones, represented by droperidol and haloperidol, function similarly by blocking dopamine receptors, proving to be moderately effective antiemetics. Specifically, olanzapine, a thienobenzodiazepine, inhibits dopamine D2 and serotonin receptors, making it an effective preventive measure against delayed nausea or vomiting associated with chemotherapy.

Despite their effectiveness, central dopamine antagonists can cause significant adverse effects, primarily extrapyramidal symptoms such as restlessness, dystonias, and Parkinsonian symptoms. Their use must be balanced with the potential for significant adverse effects.