Antiemetics for chemotherapy-induced nausea and vomiting occurring despite prophylactic antiemetic therapy

Background: Chemotherapy-induced nausea and vomiting (CINV) is a debilitating side effect. Previous studies have primarily focused on prophylactic therapy, but no published reports have evaluated the treatment of breakthrough CINV. Methods: A prospective, pilot study was performed to provide preliminary prospective evidence of the efficacy of individual agents prescribed for the treatment of breakthrough CINV. Enrolled patients were receiving moderately or highly emetogenic chemotherapy and prophylactic treatment of CINV based on antiemetic guidelines. Patients were prescribed an antiemetic for breakthrough CINV at the discretion of their treating oncologist. If patients had breakthrough CINV that required a breakthrough antiemetic medication, they were instructed to complete a questionnaire every 30 minutes for 4 hours after taking the antiemetic. Levels of nausea (0-10), vomiting, and side effects were recorded. Results: Of the 96 patients enrolled, 27 (28%) reported breakthrough nausea and/or vomiting requiring medication and completed the questionniare. Eighty-eight percent (n = 24) reported the use of prochlorperazine; they experienced a 75% median nausea reduction after 4 hours, with minimal side effects. Three patients (12%) reported the use of a 5-hydroxytryptophan (5-HT) receptor antagonist for treatment of breakthrough nausea. These patients reported a median nausea reduction of 75% after 4 hours and no perceived toxicities. Conclusions: Prochlorperazine and 5-HT receptor antagonists appear to be effective breakthrough antiemetic therapies. The described study methodology can be used to conduct randomized clinical trials to find more effective drugs for treating established nausea.