Ondansetron adverse effects

Ondansetron generally does not cause severe toxicity. Headache and constipation are the most frequent adverse effects. Light-headedness, dizziness, and transient increases in serum aminotransferase activity can occur. Extrapyramidal effects have occurred rarely, and anaphylactoid reactions have been reported. 

Granisetron and tropisetron appear to have the same safety profile as ondansetron (6). Their adverse reactions include mild rises in transaminases (up to 17%), slight headache (8-42%), transient diarrhea (2-5%), which may be followed during longer-term therapy by constipation, dizziness (5%), and dry mouth (5-17%) the incidence of xerostomia is higher than with metoclopramide. Other reported adverse effects include anorexia, paresthesia, constipation or abdominal discomfort, changes in blood pressure, fever, facial edema, leg cramps, hot flushes, and enlargement of the spleen (7). 

In a large double-blind study comparison of single-dose oral granisetron versus intravenous ondansetron in the prevention of nausea and vomiting induced by chemotherapy in 1085 patients, the drugs were equally effective and gave rise to a similar frequency of adverse effects, commonly headache, weakness, and constipation (15). Dizziness and blurred vision were reported by significantly more of the patients who received ondansetron. 

Intravenous ondansetron (4 mg at induction of anesthesia and 0.13 mg with each 1 mg bolus of morphine) has been compared with intravenous droperidol (0.5 mg at induction and 0.05 mg with each bolus of morphine) in a double-blind trial in 142 patients (22). The two regimens had similar efficacy in the prevention of postoperative nausea and vomiting. The most important adverse effect was sedation significantly more patients given droperidol (15%) had excessive sedation than patients given ondansetron (5%). 

The antiemetic effect of combined intravenous ondansetron 8 mg, oral dexamethasone 20 mg, and oral lorazepam 0.5 mg was significantly better than that of intravenous metoclopramide 10 mg, dexamethasone 20 mg, and oral lorazepam 0.5 mg in 30 patients receiving chemotherapy for ovarian cancer in a randomized trial (23). All the antiemetics were given 30 minutes before and 6 hours after chemotherapy. Significantly more patients given metoclopramide (40% versus 13%) complained of adverse effects. The most frequent adverse effects with both regimens were sedation and headache. 

In a prospective randomized, double-blind, placebo-controlled study in 100 patients scheduled for elective orthopedic surgery and presenting with pruritus induced by epidural or intrathecal morphine, intravenous ondansetron 8 mg was effective in 70% of cases and placebo in 30% (23). Ondansetron was well tolerated, did not change the degree of analgesia, and was not associated with adverse effects usually associated with ondansetron, such as headache, abdominal pain, and cardiac dysrhythmias. 

D. Toxicity Adverse effects of ketanserin are those of alpha blockade and Hj blockade. The toxicides of ondansetron, granisetron, and dolasetron include diarrhea and headache. Dolasetron has been associated with QRS and QT prolongation in the ECG and should not be used in patients with heart disease. Alosetron caused significant constipation in some patients. 

The hypotensive adverse effects of apomorphine may possibly be increased by alcohol. The concurrent use of other drugs used for erectile dysfunction or dopamine agonists or antagonists is not recommended. However, domperidone, and prochlorperazine are said not to interact when apomorphine is used for erectile dysfunction, and domperidone is the recommended antiemetic when apomorphine is used for Parkinson s disease. There is evidence that antidepressants, antiepileptics, and ondansetron do not interact adversely. 

Note that prochlorperazine should not be given if apomorphine is used for Parkinson s disease, as its dopamine antagonist actions can worsen the disease (see also Levodopa + Antiemetics , p.682). Because apomorphine is highly emetogenic at the doses required for the treatment of Parkinson s disease (1 to 4 mg/hour by subcutaneous infusion), patients with Parkinson s disease requiring apomorphine should be pretreated with domperidone 20 mg three times daily for at least 2 days. Rare reports of extrapyramidal adverse effects have been reported with ondansetron, which may be of relevance in patients with Parkinson s Disease. 

Although used extensively for the past several decades, droperidol and metoclopramide are less commonly used today because of their potential severe adverse effects, the black-box warning from the FDA for both drugs, and the comparable price of the generic ondansetron. Possible prolongation of the QT interval leading to torsade de pointes following droperidol use and tardive dyskinesia associated with metoclopramide use limit their use. However, there is little... 

The results of various clinical trials indicated that the incidence of adverse events was similar in the aprepitant group compared with the group which received only standard regimen of ondansetron and dexamethasone. The most commonly observed side effects with aprepitant treatment were asthenia, hiccups, diarrhea, gastritis, elevation in fiver function tests, and dizziness. There are also reports of thrombocytopenia and dehydration. 

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