1. Clinical Overview
Buclizine is a first-generation piperazine-derivative antihistamine (H1-receptor antagonist) with pronounced antimuscarinic, antiemetic, and sedative properties. It is structurally and pharmacologically related to cyclizine and meclizine. In the Indian context, it is primarily used for the management of nausea and vomiting, particularly in motion sickness and vertigo, and as an adjunct in migraine prophylaxis due to its vestibular suppressant and antiemetic effects. Its long duration of action allows for once or twice-daily dosing.
| Onset | Duration | Bioavailability |
|---|---|---|
| 30 to 60 minutes after oral administration. | Approximately 12 to 24 hours. | Not well-documented specifically for buclizine; estimated to be high based on its class, but precise percentage data is unavailable. |
2. Mechanism of Action
Buclizine competitively and reversibly inhibits histamine at the H1-receptor sites, particularly in the gastrointestinal tract, vestibular apparatus, and chemoreceptor trigger zone (CTZ). Its antiemetic and antivertigo actions are primarily due to its central anticholinergic (muscarinic) and antihistaminic effects on the vestibular nuclei and the vomiting center. It also exhibits mild central nervous system depression.
3. Indications & Uses
- Prophylaxis and treatment of nausea and vomiting associated with motion sickness.
- Management of vertigo associated with Meniere's disease and other vestibular disorders.
- Adjunctive therapy for the prophylaxis of migraine headaches (often in combination).
4. Dosage & Administration
Adult Dosage: For Motion Sickness/Vertigo: 25mg to 50mg orally, 1 to 2 times daily. For prophylaxis, take at least 30 minutes before travel. For Migraine: 25mg to 50mg once or twice daily as adjunctive prophylaxis.
Administration: Administer orally with or without food. For motion sickness, take the first dose at least 30 minutes before exposure to motion. Tablet should be swallowed whole with a glass of water. Avoid crushing or chewing.
5. Side Effects
Common side effects may include:
- Drowsiness/Sedation
- Dry mouth
- Blurred vision
- Constipation
- Dizziness
- Fatigue
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Alcohol, Benzodiazepines, Opioids, other CNS Depressants | Potentiation of sedative effects, increased risk of profound sedation, respiratory depression, and impaired psychomotor performance. | Major |
| Anticholinergic drugs (e.g., Atropine, Tricyclic Antidepressants, Antipsychotics) | Additive anticholinergic side effects (dry mouth, constipation, urinary retention, blurred vision, tachycardia). | Major |
| Monoamine Oxidase Inhibitors (MAOIs) e.g., Phenelzine, Selegiline | Increased anticholinergic and CNS depressant effects; risk of hypertensive crisis. | Contraindicated |
| Other antihistamines (e.g., Cetirizine, Fexofenadine) | Additive therapeutic and adverse effects, especially sedation. | Moderate |
| Hepatic Enzyme Inducers (e.g., Rifampicin, Phenytoin, Carbamazepine) | May decrease plasma concentration and efficacy of Buclizine. | Moderate |
| Hepatic Enzyme Inhibitors (e.g., Ketoconazole, Erythromycin, Cimetidine) | May increase plasma concentration and risk of toxicity of Buclizine. | Moderate |
7. Patient Counselling
- DO take the medicine as prescribed, usually 30-60 minutes before travel for motion sickness.
- DO inform your doctor about all other medicines, vitamins, and herbal supplements you are taking.
- DO use sugar-free gum or candies to relieve dry mouth.
- DO get up slowly from a sitting or lying position to avoid dizziness.
- DONT consume alcohol while on this medication.
- DONT drive, operate heavy machinery, or engage in activities requiring alertness until you know how the drug affects you.
- DONT take a double dose to make up for a missed one.
- DONT stop taking the medicine suddenly if used for migraine prophylaxis; consult your doctor.
8. Toxicology & Storage
Overdose: Symptoms are primarily extensions of its pharmacological effects: Severe CNS depression (coma, respiratory depression), CNS stimulation (hallucinations, convulsions - especially in children), anticholinergic crisis (hyperthermia, tachycardia, dilated pupils, dry hot skin, urinary retention, ileus), cardiovascular collapse.
Storage: Store at room temperature (15-25°C), protected from light and moisture. Keep in the original container, tightly closed. Keep out of reach and sight of children. Do not use after the expiry date printed on the pack.