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Ondansetron

Last updated on 09/07/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  

GENERIC NAME: Ondansetron

CHINESE NAME: 昂丹司瓊

BRAND NAME(S) IN HONG KONG: Zofran, Zofran Zydis

DRUG CLASS: Antiemetics

SUB CLASS: 5-HT3 receptor antagonists

USED FOR: Postoperative nausea and vomiting, Prevention of chemo-related nausea and vomiting, Prevention of radio-related nausea and vomiting

AVAILABLE DOSAGE FORMS:
– 4mg, 8mg (tablets)
– 4mg, 8mg (Zofran Zydis®) (orodispersible tablets)
– 2mg/ml, 4mg/2ml. 8mg/4ml (injections)

What is Ondansetron for?

Ondansetron belongs to a class of medications called 5-HT3 receptor antagonists. It can suppress a chemical in the brain which causes nausea and vomiting. It is indicated for the prevention of chemotherapy-induced, radiotherapy-induced, and postoperative nausea and vomiting.

How to use it?

Ondansetron can be taken orally as conventional tablets or orodispersible tablets. It can also be administered intravenously. Listed below are the indications and the dosages.

Prevention of nausea/vomiting associated with high-emetogenic chemotherapy:
Oral tablets: 24 mg once
Intravenous injection: 8-16 mg once

Note:
Day of chemotherapy: administer prior to chemotherapy and in combination with a NK-1 receptor antagonist, Dexamethasone (with/without Olanzapine).
– Post–chemotherapy days: Ondansetron use is not necessary

Prevention of nausea/vomiting associated with moderate-emetogenic chemotherapy:
Oral tablets: 8 mg twice daily, with the 1st dose given prior to chemo and the 2nd dose given 8 hours later
Intravenous injection: 8-16 mg once

Note:
– Day of chemotherapy: administer prior to chemotherapy and in combination with Dexamethasone (with/without NK-1 receptor antagonist).
– Post-chemotherapy days: Ondansetron / NK-1 receptor antagonist / Dexamethasone monotherapy

Prevention of nausea/vomiting associated with low-emetogenic chemotherapy:
Oral tablets: 8 mg once prior to chemotherapy
Intravenous injection: 8 mg once prior to chemotherapy

Prevention of nausea/vomiting associated with oral chemotherapy agents:
Oral tablets: 8-16 mg once prior to chemotherapy as needed

Prevention of postoperative nausea and vomiting:
Oral tablets: 8-16 mg 1 hour before anesthesia induction
Intravenous injection: 4 mg before anesthesia induction or at the end of surgery

Prevention of nausea/vomiting associated with radiotherapy:
8 mg once or twice daily, administered 1-2 hours prior to each fraction of radiation in combination with Dexamethasone.

What are the side effects of Ondansetron?

Common side effects of Ondansetron include constipation, fatigue, and headache.

Who should not take Ondansetron?

– People who are allergic to Granisetron, other 5-HT3 receptor antagonists, or any component of the formulation
– Concomitant use of Apomorphine

Pharmacist Tips:

If orodispersible tablet is used, place it on your tongue and let it dissolve. Water is not needed. Do not swallow it whole. Do not chew, break, or crush it.

Common dosing schedule:
Ondansetron can be taken with or without food. Please refer to the above section for specific administering instruction.

This schedule is for reference only, adjustments may be made according to individual needs.

Some common medications Ondansetron may interact with:
Tramadol
Fentanyl
– Antidepressants, e.g. Fluoxetine, Paroxetine
– Antibiotics, e.g. Clarithromycin, Erythromycin
– Antiarrhythmics, e.g. Amiodarone, Sotalol
– Apomorphine

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Ondansetron in Hong Kong?

In Hong Kong, Ondansetron is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at https://www.drugoffice.gov.hk

Need more information?

For detailed information about the use of Ondansetron in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.