Treatment of Cyclical Vomiting Syndrome Unresponsive to Zofran (Ondansetron)
Cyclical vomiting syndrome (CVS) is a chronic disorder characterized by episodes of nausea, vomiting, and retching, separated in time by episode-free periods. The management of CVS involves abortive therapy to terminate episodes and prophylactic therapy to prevent episodes.
Abortive Therapy
For patients unresponsive to Zofran (ondansetron), other antiemetic options can be considered.
- Metoclopramide (PO): Metoclopramide can be used as an alternative to ondansetron for abortive therapy in CVS. However, its use is limited by potential side effects, including extrapyramidal symptoms, tardive dyskinesia, and neuroleptic malignant syndrome 1.
- Aprepitant: Aprepitant, a neurokinin 1 receptor antagonist, has been reported to be effective in a patient with severe CVS who failed oral ondansetron therapy. A dose of 125 mg on the first day and 85 mg on subsequent days can be tried 2.
Prophylactic Therapy
For patients with moderate to severe CVS, prophylactic therapy is recommended.
- Tricyclic Antidepressants (TCAs): TCAs, such as amitriptyline, are commonly used as prophylactic therapy in CVS. However, some patients may not respond to TCAs, and alternative therapies should be considered 3.
- Cannabis Abstinence: For patients with CVS who use cannabis, abstinence from cannabis may be beneficial in reducing symptoms.
Other Treatment Options
Other treatment options for CVS include:
- Intravenous Midazolam and Clonidine: A combination of intravenous midazolam and clonidine has been reported to be effective in a patient with CVS who was unresponsive to ondansetron and other therapies 4.
- Lifestyle Modifications: Lifestyle modifications, such as stress management, avoidance of triggers, and hot water bathing or showering, can also be beneficial in managing CVS symptoms.
Recommendation
For patients with cyclical vomiting syndrome unresponsive to Zofran (ondansetron), aprepitant 125 mg on the first day and 85 mg on subsequent days can be tried as an alternative abortive therapy.
This recommendation is based on the available evidence and expert consensus. However, it is essential to note that CVS is a complex disorder, and treatment should be tailored to the individual patient's needs and response to therapy.
Algorithm for Deciding
- Assess CVS Severity: Evaluate the patient's CVS severity using the ANMS-CVSA clinical guideline criteria.
- Evaluate Current Therapy: Assess the patient's current therapy, including dose and response to therapy.
- Consider Alternative Therapies: Consider alternative therapies, such as aprepitant, metoclopramide, or other antiemetic agents.
- Monitor Response: Monitor the patient's response to new therapy and adjust as needed.
By following this algorithm and considering the available evidence, clinicians can make informed decisions about the management of CVS in patients unresponsive to Zofran (ondansetron).