Nausea and vomiting is a drag! Hope no one is feeling queasy since this talk is all about N/V.
Dr. Eric Prommer is very knowledgeable about serotonin and the serotonin antagonist like ondansetron . Interestingly, serotonin, which is constantly being produced, can overcome the antagonist and this is why these medications may lose effectiveness.
At this time these medications are used for prevention of chemotherapy induce, post-op and radiation induced nausea\ vomiting. Most serotonin activity is increased in the first 24-48 hours after the insult. Therefore this is why these medications are mostly used in theses settings? The issue in palliative medicine is that we are trying to manage the problem of nausea \vomiting in a more chronic setting and not specifically related to a specific event.
Evidence Base is Limited
Opioid Induced Emesis
Ondasnsetron versus reglan may be helpful?
24 patients granesetron 3mg +dexamethasone 8mg
Highly effective with good control in over 80% of patients
280 patients with advance cancer but commonly on opioids the N\V may be in part the cause of nausea\vomiting.
Total Control of N\V which was less than 3 hours of distress a day could be achieved in up 75-85 % of patients with relatively minimal side-effects. However, study flawed in several ways but very suggestive to be highly effective.
1) Serotonin antagonists are not all alike- Therefore it may be that when one is not working that a different drug in this class and or dose may be helpful .
2) Efficacy is studied in Opioid and bowel obstruction
3) Minimal adverse effect
4) Usable in combination with other agents and steroids.
5) The cost of the agents can be extremely high.
6) More studies are needed to use these medications wisely