Ondansetron Aurobindo (Ondansetron)

Ondansetron is a serotonin (5‑HT₃) receptor antagonist indicated for several nausea and vomiting pathways.

• Chemotherapy‑induced nausea and vomiting: helps prevent and control acute and delayed episodes.
• Radiation‑induced nausea and vomiting: reduces the incidence of nausea during and after radiotherapy.
• Post‑operative nausea and vomiting: decreases the frequency of nausea and vomiting after surgical procedures.
• Pregnancy‑related nausea (hyperemesis gravidarum): used when other treatments are ineffective, under specialist supervision.
• Gastroenteritis‑related nausea: alleviates nausea associated with acute gastroenteritis.

• Ondansetron blocks the action of serotonin at the 5‑HT₃ receptors located in the chemoreceptor trigger zone of the brain and on vagal afferent nerves in the gastrointestinal tract. By inhibiting this receptor, it prevents the initiation of the vomiting reflex triggered by chemotherapeutic agents, radiation, or surgical stimuli.

Ondansetron is generally well tolerated, but adverse reactions can occur.

Common Side Effects

• Headache: mild to moderate intensity.
• Constipation: occasional bowel habit changes.
• Diarrhoea: transient loose stools.
• Fatigue: feeling of tiredness.
• Dizziness: light‑headed sensations.
• Injection site pain (if administered intravenously).

Serious or Rare Side Effects

• Cardiac arrhythmia: QT‑interval prolongation, especially with IV use.
• Severe allergic reaction: rash, itching, swelling, or anaphylaxis.
• Serotonin syndrome: rare when combined with other serotonergic drugs.
• Hepatic dysfunction: elevated liver enzymes.
• Severe hypotension: sudden drop in blood pressure.
• Neuroleptic malignant‑like syndrome: extremely rare neurological emergency.

When using Ondansetron, consider the following safety measures:

• Cardiac monitoring: assess baseline ECG in patients with known heart rhythm disorders.
• Drug interactions: review concomitant medications that may affect QT interval.
• Pregnancy: use only if clearly needed; discuss risks with a healthcare provider.
• Lactation: evaluate benefits versus potential infant exposure.
• Renal/hepatic impairment: dose adjustment may be required; monitor organ function.
• Store at ambient temperature: keep below 25°C, retain original packaging, protect from moisture and direct sunlight.

Ondansetron may interact with several medicines, affecting its safety profile.

Major Interactions (Avoid)

• Apomorphine: concurrent use can cause profound hypotension and loss of consciousness.
• Certain anti‑arrhythmic agents (e.g., amiodarone, quinidine): increase risk of QT prolongation.
• Other serotonergic drugs (e.g., SSRIs, MAOIs, tramadol): may precipitate serotonin syndrome.

Moderate Interactions (Monitor Closely)

• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): may raise ondansetron plasma levels.
• CYP2D6 substrates (e.g., codeine, metoprolol): ondansetron can modestly affect their metabolism.
• Diuretics (e.g., furosemide): may enhance hypotensive effects.
• Anticholinergic agents: may reduce the anti‑emetic efficacy of ondaconf.