In small doses, phenothiazines are primarily used as?

Phenothiazines, when administered in small doses, are primarily recognized for their effectiveness as antiemetics. This class of medications works by blocking dopamine receptors in the brain, particularly in the area of the brain known as the chemoreceptor trigger zone (CTZ), which is responsible for nausea and vomiting. By inhibiting the action of dopamine, phenothiazines help to prevent the feeling of nausea and help reduce vomiting.

While phenothiazines are also utilized in larger doses as antipsychotics to treat conditions such as schizophrenia or severe anxiety, their antiemetic properties make them particularly valuable in the management of nausea and vomiting, especially those associated with chemotherapy, postoperative conditions, or other medical treatments.

The other options do not align with the primary use of phenothiazines in small doses. They are not recognized as antiviral agents or antidepressants, thereby reinforcing their classification and usage primarily as antiemetics in this context.