Ondansetron

Generic Name: Ondansetron
Common Brand Names: Zofran, Zuplenz

Introduction

Ondansetron is a selective serotonin 5-HT3 receptor antagonist used to prevent and treat nausea and vomiting associated with chemotherapy, radiation therapy, and postoperative recovery.

Conditions of Use (Indications)

1. Chemotherapy-Induced Nausea and Vomiting (CINV):

• Effective for acute and delayed phases of CINV.

2. Radiation-Induced Nausea and Vomiting (RINV):

• Adjunct to radiotherapy.

3. Postoperative Nausea and Vomiting (PONV):

• Prevention and treatment.

Mechanism of Action

Ondansetron blocks serotonin (5-HT3) receptors located in the chemoreceptor trigger zone (CTZ) of the brain and the gastrointestinal tract. By inhibiting these receptors, ondansetron prevents the vomiting reflex initiated by emetogenic signals.

Side Effects

1. Common Side Effects:

• Headache, constipation, dizziness, fatigue.

2. Serious Side Effects:

• QT prolongation, torsades de pointes, serotonin syndrome (when used with other serotonergic drugs).

Harmful Interactions

1. Drugs that Prolong QT Interval (e.g., amiodarone):

• Increased risk of torsades de pointes.

2. Serotonergic Drugs (e.g., SSRIs, SNRIs):

• Risk of serotonin syndrome.

3. Apomorphine:

• Severe hypotension and loss of consciousness.

Contraindications

1. Congenital long QT syndrome.
2. Hypersensitivity to ondansetron or other 5-HT3 receptor antagonists.
3. Concurrent use with apomorphine.

Latest References

1. ASCO Guidelines for Management of CINV (2023).
2. Journal of Clinical Oncology (2023): Advances in Antiemetics.
3. FDA Safety Communication on Ondansetron and QT Prolongation (2023).