Ondansetron as Rescue Medication

Ondansetron as Rescue Medication

PEP Topic 
Chemotherapy-Induced Nausea and Vomiting—Adult

Ondansetron is a 5-HT3 receptor antagonist antiemetic that works by blocking serotonin receptors in the chemoreceptor trigger zone. Ondansetron usually is part of an ongoing basal antiemetic regimen. Ondansetron also has been evaluated for use as a rescue medication to treat episodes of chemotherapy-induced nausea and vomiting (CINV) that are not otherwise controlled.

Effectiveness Not Established

Research Evidence Summaries

Fabi, A., Ciccarese, M., Metro, G., Savarese, A., Giannarelli, D., Nuzzo, C.M., … Cognetti, F. (2008). Oral ondansetron is highly active as rescue antiemetic treatment for moderately emetogenic chemotherapy: Results of a randomized phase II study. Supportive Care in Cancer, 16, 1375–1380. 

doi: /10.1007/s00520-008-0438-9

Study Purpose:

To test the efficacy and safety of two different schedules of ondansetron as rescue antiemetic treatment in patients who were refractory to standard antiemetic prophylaxis for delayed emesis following moderately emetogenic chemotherapy (MEC)

Intervention Characteristics/Basic Study Process:

Patients were randomly allocated to one of two treatment groups for rescue antiemetic treatment: intramuscular ondansetron 8 mg or oral ondansetron 16 mg for days two to six (antiemetic prophylaxis was provided by ondansetron 8 mg IV plus dexamethasone 8 mg IV for acute emesis and dexamethasone 8 mg for four days for delayed emesis).

Sample Characteristics:

  • The sample consisted of 89 participants.
  • In the intramuscular ondansetrong group, the average patient age was 58 years with a range of 27–83 years. In the oral ondansetron group, the average age was 61 years with a range of 28–79).
  • The sample was 85.4% female and 14.6% male.
  • The majority had breast, lung, and gynecologic cancers.
  • Patients received either an anthracycline chemotherapy regimen (highly emetogenic chemotherapy [HEC], MEC), a carboplatin regimen, or an irinotecan/oxaliplatin regimen.


The study was conducted at a single site, outpatient setting.

Phase of Care and Clinical Applications:

All patients were in active treatment.

Study Design:

The study design was a prospective trial (open label, phase II, randomly assigned to treatment group).

Measurement Instruments/Methods:

  • Participants recorded in diaries the dates and times of emetic episodes, severity of nausea or vomiting, use of rescue treatment, and efficacy of treatment (absence or presence of further emetic events).
  • Participants also rated their personal satisfaction with the assigned rescue medication (satisfied, partially satisfied, unsatisfied).
  • The Common Terminology Criteria for Adverse Events (NCI-CTCAE. V. 3.0) was used.


Oral ondansetron 16 mg was significantly superior to intramuscular ondansetron 8 mg for nausea and vomiting control during days two to six (p < 0.01). The two arms had a similar adverse event profile. A higher degree of personal satisfaction was found with oral ondansetron.


Because of its high efficacy and excellent tolerability, oral ondansetron is an important option in the management of MEC-related delayed emesis refractory to standard antiemetic prophylaxis.


  • The sample was small with fewer than 100 participants.
  • No control group was included.
  • The frequency of the use of rescue medication was not reported, which may have contributed to the study results (ease of access to phone orders may have contributed to better efficacy and more satisfaction.)
  • Interpretation of results as a pure difference between orodispersible ondansetron and intramuscular ondansetron is difficult.

Nursing Implications:

The oral form of ondansetron could provide satisfactory rescue for breakthrough delayed emesis when compared to the Intramuscular form of ondansetron, with a similar adverse event profile.