Ondansetron

It is a potent highy selective antagonist at the5hydroxytryptamine receptors sbtype3 (5HT3). It can effectively control vomiting due to anticancer drugs as well as raiotherapy. Unlike metoclopramide, ondansetron is not a lopomide antagonist and doen't cause dystonia or extra pyramidal effects. It is a carbazole which causes antinauseant &antiemetic effects by selective & competitive blockade of the 5HT3 receptors.

Indications

Vomiting and nausea associated with cytoxic radiotherapy & chemotherapy, prophylaxi & treatment of postoperative vomiting and nausea.

Dosage

8mg as a slowI.V.injection given just before cheotherapy or radiotherapy or 8mg orally1-2 hours before.This is followed by 8mg orally every 12 hours.

Contra-Indications

Hypersensitivity.

Special Precautions

Liver diseases, constipation, headache. Paediatrics: Reduced dose necessary. Not recommended below the age of 4 years. Pregnancy: Safety not established. use only, if clearly indicated. Lactation: The drug passes into breast milk. Elderly: No special problem.

Side Effects

Headache,constipation, sensation of flushing in the head and epigastrium, rarely allergic reactions.

Drug Interactions

Dexamethasone enhances the effect of the drug.