Using Ondansetron to Prevent Fainting Episodes
Official title: A Proof of Principle Study of Ondansetron for the Prevention of Vasovagal Syncope: The Eleventh Prevention of Syncope Trial (POST11)
Run by University of Calgary · NCT05755737 · Data updated 2026-11-12
This study is testing if the medication ondansetron can help adults who frequently faint feel better and prevent future fainting spells.
Quick facts
| Phase | Phase 2 |
|---|---|
| Study type | Interventional |
| Ages | 18 Years to 100 Years |
| Sex | All |
| Enrollment | 70 (estimated) |
| Sponsor | University of Calgary Academic / other |
| Locations | 1 site (Calgary, Alberta) |
| Status | Recruiting |
| Started | June 1, 2023 |
| Main results expected | December 31, 2025 |
| Study ends | December 31, 2026 |
| Registry record updated | May 10, 2024 |
| Trial ID | NCT05755737 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Ideal candidates are adults aged 18 and older who have experienced at least one syncopal spell in the past year and meet specific diagnostic criteria for vasovagal syncope.
✕Probably not a fit
Patients with other causes of syncope, significant cardiovascular issues, or those who are pregnant or lactating may not benefit from this study.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This clinical trial investigates the effectiveness of ondansetron, a serotonin 5HT3 receptor inhibitor, in preventing vasovagal syncope (VVS) in adults who have experienced recurrent fainting spells. The study will involve 70 participants who meet specific diagnostic criteria for VVS and will be randomized to receive either ondansetron or a placebo in a double-blind manner. Participants will undergo a tilt table test to assess the drug's impact on syncope and presyncope episodes, with continuous monitoring of heart rhythm and blood pressure. The results aim to provide preliminary data for future larger-scale trials.
Why it matters
Potential benefit: If successful, this treatment could significantly reduce the frequency of fainting episodes and improve the quality of life for patients suffering from vasovagal syncope.
How similar studies have gone: While there are few established therapies for vasovagal syncope, this approach using ondansetron is novel and has not been extensively tested in this context.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria: (A) ≥1 syncopal spells in the year preceding enrolment (B) ≥-2 points on the Calgary Syncope Symptom Score( Accurate Calculation for Diagnosis of Vasovagal Syncope) (C) Age ≥18 years with informed consent Exclusion Criteria: 1. other causes of syncope, such as ventricular tachycardia, complete heart block, orthostatic hypotension or hypersensitive carotid sinus syndrome 2. an inability to give informed consent 3. important valvular, coronary, myocardial or conduction abnormality or significant arrhythmia 4. hypertrophic cardiomyopathy 5. a permanent pacemaker 6. a seizure disorder 7. hypertension defined as \>160/90 mm Hg 8. pregnancy 9. lactating women 10. glaucoma 11. medications with known effects on BP 12. Known hypersensitivity to ondansetron and related medications 13. other factors which, in the investigator's opinion, would prevent the subject from completing the protocol.
Where it's running
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University of Calgary
Calgary, Alberta, Canada Recruiting
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.