Ondansetron Pharmacology

Ondansetron

About Ondansetron
Selective serotonin 5-HT3 receptor antagonist, Imidazole derivative, Antiemetic.
Mechanism of Action of Ondansetron
Ondansetron is a selective 5HT3 receptor antagonist. 5HT3 receptors are present in vagal nerve terminals and chemoreceptor trigger zone of area postrema of the brain.
Cytotoxic chemotherapy is associated with release of Serotonin from Enterochromaffin cells in the small intestine. Serotonin triggers vomiting through 5HT3 vagal receptor that activates the vomiting reflex. Since Ondansetron is a 5HT3 receptor antagonist, it is indicated for the prevention of nausea and vomiting associated in chemotherapy.
Anaesthetic adjuncts: It is used preoperatively in order to reduce the post operative vomiting.

Pharmacokinets of Ondansetron
Absorption: Ondansetron is well absorbed after oral administration and the bioavailability is 50 - 60 %.
Distribution: It is distributed in protein bound form.
Metabolism: Ondansetron is extensively metabolised in the liver.
Excretion: It is excreted mainly in urine.
Onset of Action for Ondansetron
With in 30 minutes
Duration of Action for Ondansetron
8 - 10 hours
Half Life of Ondansetron
4 - 6 hours
Side Effects of Ondansetron
1. Headache
2. Dizziness
3. Constipation
4. Musculoskeletal pain
5. Chills
6. Allergic reactions
7. Agitation
8. Chest pain
9. Malaise
10. Urinary retention
11. Elevation in hepatic enzymes
12. Hypotension

Contra-indications of Ondansetron
1. Hypersensitivity to Ondansetron
Special Precautions while taking Ondansetron
1. Hepatic impairment
2. Intestinal obstruction
Pregnancy Related Information
Contraindicated
Old Age Related Information
May be used
Breast Feeding Related Information
Use with caution
Children Related Information
Use with caution
Below 6 months : Contraindicated
Indications for Ondansetron
1. Nausea and vomiting associated with cytotoxic chemotherapy or radiotherapy.
2. Post operative nausea and vomiting
Interactions for Ondansetron
Inducers of hepatic cytochrome P450 drug metabolising enzymes: May change the clearance and hence the half-life of ondansetron, but on the basis of available data there is no need to adjust the dose of ondansetron.
Typical Dosage for Ondansetron
Adult:
Oral :
Nausea and vomiting associated with cytotoxic chemotherapy or radiotherapy:8 mg should be given 1 - 2 hour before chemotherapy or radiotherapy and repeat the same dose after the procedure every 12 hours for 1 - 2 days.
Post operative nausea and vomiting: 16 mg should be given 1 hour before anesthesia or soon after operation
IV Injection :
Nausea and vomiting associated with cytotoxic chemotherapy or radiotherapy: 0.15 mg / kg IV infusion over 15 minutes should be given half an hour before starting treatment and repeat the same dose 4th and 8th hour after first dose or a single dose of 32 mg IV infusion over 15 minutes should be given half an hour before starting the treatment.
Post operative nausea and vomiting: 4 mg IV should be given immediately before anesthesia or soon after operation
Children :
Oral :
Nausea and vomiting associated with cytotoxic chemotherapy or radiotherapy:8 mg should be given 1 - 2 hour before chemotherapy or radiotherapy and repeat the same dose after the procedure every 12 hours for 1 - 2 days
Injection:
Nausea and vomiting associated with cytotoxic chemotherapy or radiotherapy:0.15 mg / kg IV infusion over 15 minutes should be given half an hour before starting treatment and repeat the same dose 4th and 8th hour after first dose
Children below 2 years: 0.1 mg / kg body weight as IV infusion
Maximum dose: 4 mg



Schedule of Ondansetron
N/A
Storage Requirements for Ondansetron
Store at room temperature. Protect from heat and light. Keep out of the reach of children.
Effects of Missed Dosage of Ondansetron
If you missed a dose and do not feel nauseated then skip the missed dose and go back regular schedule.
If you missed a dose and feel nauseated then take the missed dose as soon as possible.
Effects of Overdose of Ondansetron
Give supportive measures and symptomatic treatment.

Home Delivery for Ondansetron in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including ondansetron.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for ondansetron and other medicines and health products. Home delivery services for ondansetron may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take ondansetron only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for ondansetron before they complete the sale. You can get this information while placing the order for ondansetron with the pharmacy.

Ondansetron is a generic medicine name and there are several brands available for it. Some of the brands for ondansetron might be better known than ondansetron itself. If the pharmacy that's willing to deliver medicines to your home doesn't have ondansetron in stock, you can ask for one of the branded alternatives for ondansetron.