Otobrol (Ondansetron)

Ondansetron is used to manage nausea and vomiting by targeting the serotonergic pathways involved in emesis.

• Chemotherapy‑induced nausea and vomiting: helps prevent and control acute and delayed episodes.
• Radiation‑induced nausea and vomiting: reduces the frequency and severity of symptoms.
• Post‑operative nausea and vomiting: decreases the incidence of nausea after surgical procedures.

• Ondansetron selectively blocks the 5‑hydroxy‑tryptamine type 3 (5‑HT3) receptors located in the gastrointestinal tract and the chemoreceptor trigger zone of the brain. By inhibiting serotonin binding at these sites, it interrupts the neural signaling cascade that initiates the vomiting reflex, providing anti‑emetic protection during chemotherapy, radiotherapy and surgery.

Side effects reported with ondansetron are generally mild to moderate and vary by individual.

Common Side Effects

• Headache: mild to moderate intensity.
• Constipation: occasional bowel movement difficulty.
• Diarrhoea: loose stools in some patients.
• Fatigue: feeling of tiredness or reduced energy.
• Dizziness: transient light‑headedness.

Serious or Rare Side Effects

• Cardiac arrhythmia: QT‑interval prolongation may lead to irregular heart rhythms.
• Severe allergic reaction: rash, itching, swelling, or difficulty breathing.
• Serotonin syndrome: rare but potentially life‑threatening condition when combined with other serotonergic agents.
• Hepatic dysfunction: elevated liver enzymes indicating liver stress.
• Vision changes: blurred or altered visual perception.

When using Ondansetron, consider the following safety measures:

• Cardiac monitoring: patients with known QT prolongation or electrolyte imbalance should be observed.
• Drug interactions: review concomitant medications for serotonergic activity.
• Pregnancy: use only if the potential benefit outweighs risk; consult obstetric guidance.
• Breastfeeding: weigh benefits against potential infant exposure.
• Renal or hepatic impairment: dose adjustment may be required based on clinical judgment.
• Store at below 25°C: keep in the original packaging, protect from moisture and direct sunlight.

Ondansetron may interact with several medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

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

Moderate Interactions (Monitor Closely)

• Serotonergic agents (SSRIs, SNRIs, MAO inhibitors): may raise serotonin syndrome risk.
• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): can elevate ondansetron plasma levels.
• CYP3A4 inducers (e.g., rifampicin): may reduce ondolanetil