Ondansetrone Hikma (Ondansetron)

Ondansetron is employed across several clinical pathways that involve nausea and vomiting control.

• Chemotherapy‑induced nausea and vomiting (CINV): helps reduce the frequency and severity of nausea and vomiting associated with cancer‑directed chemotherapy.
• Radiation‑induced nausea and vomiting (RINV): lessens nausea and vomiting that occur during or after radiation treatment.
• Post‑operative nausea and vomiting (PONV): decreases the incidence of nausea and vomiting after surgical procedures.
• Pregnancy‑related nausea (hyperemesis gravidarum): provides symptomatic relief for severe nausea and vomiting during pregnancy.

• Ondansetron blocks the action of serotonin at the 5‑HT3 receptors located on vagal nerve terminals and in the chemoreceptor trigger zone of the brain. By inhibiting this receptor, it prevents the initiation of the vomiting reflex that is triggered by chemotherapeutic agents, radiation, or surgical stress.

Side effects of ondansetron are generally mild but can vary in frequency.

Common Side Effects

• Headache: mild to moderate intensity.
• Constipation: reduced bowel movements.
• Diarrhoea: loose stools.
• Fatigue: feeling of tiredness.
• Dizziness: light‑headed sensation.

Serious or Rare Side Effects

• Cardiac arrhythmia: irregular heart rhythm, including QT prolongation.
• Severe allergic reaction: rash, itching, swelling, or difficulty breathing.
• Serotonin syndrome: agitation, confusion, rapid heart rate, and high blood pressure.
• Hepatic dysfunction: elevated liver enzymes indicating liver stress.

When using ondansetron, consider the following safety measures:

• Cardiac monitoring: patients with known QT prolongation or electrolyte imbalance should be monitored.
• Electrolyte balance: correct potassium, magnesium, and calcium levels before administration.
• Concomitant medications: review other drugs that may affect cardiac rhythm.
• Pregnancy: use only if clearly needed, as safety data are limited.
• Breastfeeding: assess risk‑benefit before use.
• Store at below 25°C: keep in the original container, protect from moisture and direct sunlight.

Ondansetron may interact with several medicines, requiring attention to the interaction severity.

Major Interactions (Avoid)

• Apomorphine: may cause profound hypotension and loss of consciousness.
• Certain anti‑arrhythmic drugs (e.g., amiodarone, quinidine) that prolong QT interval.

Moderate Interactions (Monitor Closly)

• Other serotonergic agents (e.g., SSRIs, SNRIs, tramadol) – risk of serotonin syndrome.
• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) – may increase ondansetron levels.
• CYP2D6 inhibitors (e.g., fluoxetine, paroxetine) – may raise plasma concentrations.
• Digoxin: may increase serum digoxin concentrations.