Ondansetron Accord (Ondansetron)

Ondansetron Accord is a selective 5‑HT3 receptor antagonist used to prevent and treat nausea and vomiting in several clinical settings.

• Chemotherapy‑induced nausea and vomiting: Reduces the frequency and severity of acute and delayed episodes.
• Radiation‑induced nausea and vomiting: Helps control nausea during and after radiotherapy.
• Post‑operative nausea and vomiting: Decreases the incidence of nausea and vomiting after surgery.
• Pregnancy‑related hyperemesis gravidarum (off‑label): May be used when conventional therapy fails, under specialist supervision.

• Ondansetron blocks the serotonin 5‑HT3 receptors located on vagal afferent nerves in the gastrointestinal tract and in the chemoreceptor trigger zone of the brain. By preventing serotonin from binding to these receptors, it interrupts the neural signaling cascade that initiates the vomiting reflex, thereby reducing nausea and vomiting.

Common Side Effects

• Headache: mild to moderate intensity.
• Constipation: occasional bowel movement difficulty.
• Diarrhoea: loose stools, usually transient.
• Fatigue: feeling of tiredness or reduced energy.
• Dizziness: light‑headed sensation.
• Injection site reactions (if applicable): mild erythema or discomfort.

Serious or Rare Side Effects

• Cardiac arrhythmia: QT‑interval prolongation, especially with high doses.
• Severe hypersensitivity: rash, itching, swelling, or anaphylaxis.
• Serotonin syndrome: agitation, hyperreflexia, fever when combined with serotonergic agents.
• Hepatic dysfunction: elevated liver enzymes.
• Neuroleptic malignant‑like syndrome: rare extrapyramidal signs.
• Persistent visual disturbances: blurred vision or photophobia.

Before prescribing Ondansetron Accord, consider the following precautions:

• Cardiac risk assessment: evaluate baseline ECG in patients with known cardiac disease.
• Electrolyte monitoring: correct hypokalaemia, hypomagnesemia, or hypocalcaemia before use.
• Drug‑interaction review: avoid concurrent use with other QT‑prolonging agents.
• Pregnancy and lactation: weigh benefits against potential risks; use only if clearly needed.
• Renal or hepatic impairment: dose adjustment may be required based on clinical judgement.
• Store at ambient temperature: keep in the original container, protect from moisture and direct sunlight.

Ondansetron may interact with several medicines that affect cardiac rhythm or serotonin pathways.

Major Interactions (Avoid)

• Other QT‑prolonging drugs (e.g., quinidine, haloperidol): increase risk of arrhythmia.
• Serotonergic agents (e.g., SSRIs, MAOIs, tramadol): may precipitate serotonin syndrome.

Moderate Interactions (Monitor Closely)

• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): raise ondansetron plasma levels.
• CYP2D6 substrates (e.g., metoprolol, codeine): may have altered metabolism.
• Antacids containing aluminium or magnesium: can reduce oral absorption.
• Digoxin: modest increase in serum concentrations.
• Alcohol: may enhance central nervous system depression.