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Author: Admin | 2025-04-28
Monograph on ondansetroncautions & contraindicationsContraindication: QT prolongation or high risk of Torsade de Pointes (e.g., untreated hypokalemia).Ondansetron can prolong QT interval and cause Torsade de Pointes. (29259513)Among commonly utilized antiemetics, ondansetron might carry a relatively higher risk of Torsade de Pointes than other agents. In contrast, there is widespread concern regarding haloperidol or droperidol, but the risk of Torsade de Pointes is probably minimal at the tiny doses of droperidol or haloperidol which are used to treat nausea.Although ondansetron might be riskier than some other antiemetics, the absolute risk of arrhythmia remains low. Ondansetron is one of the most widely utilized medications, yet relatively few reports exist of its causing Torsade de Pointes.(24314899) Interestingly, many of these events occurred within 1-2 minutes of rapidly pushing ondansetron โ an unnecessarily risky practice which should probably be avoided (figure above).The most common side effects are mild headache (1/36 patients) and constipation (1/23 patients).palonosetronPalonosetron is a second-generation 5HT3 antagonist, with the following advantages compared to ondansetron:Absence of QT prolongation (perhaps the greatest advantage).(26111957)Longer half-life (~40 hours).Superior efficacy compared to ondansetron (especially the 8-mg dosing of ondansetron).0.25 mg palonosetron IV is a commonly used dose for prevention of chemotherapy-induced nausea and vomiting.(26345982)There are no real contraindications to palonosetron (aside from a history of anaphylaxis to the drug).The main drawback is cost and availability. Palonosetron is a bit more expensive than ondansetron (a single 0.25 mg dose costs $130 according to goodrx.com). However, improved efficacy and reduced need to redose palonosetron can render it cost-effective. (17532704) More: ๐ MedScape monograph on palonosetronphenothiazines (prochlorperazine, chlorpromazine, promethazine)(back to contents)general commentsProchlorperazine (COMPAZINE) is more selective for D2 receptors. This comes with advantages and disadvantages:Advantage: Less sedation than other phenothiazines.Disadvantage: Higher rate of extrapyramidal side effects (e.g., akathisia, dystonia).Prochlorperazine is available over the counter in the United States, implying
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