Prochlorperazine is perhaps the most frequently (and empirically) used antiemetic and, in low doses, is generally effective in preventing nausea associated with radiation therapy and in treating N&V attributed to very low to moderately emetogenic chemotherapeutic drugs. Prochlorperazine is a phenothiazine and can be given orally, IM, IV, and rectally. It is usually given in the 10- to 50-mg dose range (pediatric dose for children who weigh >10 kg or who are >2 years: orally or rectally, 0.4 mg/kg/dose tid–qid; or IM, 0.1–0.15 mg/kg/dose tid–qid, maximum 40 mg/d). Higher prochlorperazine doses (e.g., 0.2–0.6 mg/kg/dose) are also given IV for patients receiving chemotherapy with high emetogenic potential.;[Level of evidence: I] Phenothiazines may be of particular value in treating patients who experience delayed N&V (postacute phase symptoms) on cisplatin regimens.[Level of evidence: I]
As with other dopaminergic antagonists, the most common side effects of prochlorperazine are EPRs (acute dystonias, akathisias, neuroleptic malignant syndrome [uncommon], and rarely, akinesias and dyskinesias) and sedation. Marked hypotension may also result if IV prochlorperazine is administered rapidly at high doses. Administration over at least 30 minutes appears adequate to prevent hypotensive episodes.[6,7,8]
Droperidol and haloperidol
Droperidol and haloperidol represent another class of dopaminergic (D2 subtype) receptor antagonists that are structurally and pharmacologically similar to the phenothiazines. While droperidol is used primarily as an adjunct to anesthesia induction, haloperidol is indicated as a neuroleptic antipsychotic drug; however, both agents have some antiemetic activity. Droperidol is administered IM or IV, typically from 1 to 2.5 mg every 2 to 6 hours, but higher doses (up to 10 mg) have been safely given.[9,10] Haloperidol is administered IM, IV, or orally, typically from 1 to 4 mg every 2 to 6 hours. Results of a small, uncontrolled, open-label study showed some efficacy for haloperidol in palliative care patients. Both agents may produce EPRs, akathisia, hypotension, and sedation.
Dopamine 2 Antagonists