Cyclizine is an antihistamine drug used to treat nausea, vomiting and dizziness associated with motion sickness, vertigo and post-operative following administration of general anaesthesia and opioids.

Pharmacology

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Cyclizine is a piperazine derivative with histamine H₁-receptor antagonist (antihistamine) activity. The precise mechanism of action in inhibiting the symptoms of motion sickness is not well understood. It may have effects directly on the labyrinthine apparatus and on the chemoreceptor trigger zone. Cyclzine exerts a central anticholinergic (antimuscarinic) action.

Contraindications

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Its antimuscarinic action warrants caution in patients with prostatic hypertophy, urinary retention, glaucoma. Liver disease exacerbates its sedative effects.

Side effects

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Common (>10%) - Drowsiness

Uncommon (1% to 10%) - Headache, psychomotor impairment, and antimuscarinic effects such as urinary retention, xerostomia (dry mouth), blurred vission and gastro-intestinal disturbances.

Rare - Hypersensitivity reactions (bronchospasm, angioedema, anaphylaxis, rashes and photosensitivity reactions), extrapyramidal effects, dizziness, confusion, depression, sleep disturbances, tremor, liver dysfunction.

Formulations

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As cyclizine hydrochloride 50mg tablets and cyclizine lactate solution for intramuscular or intravenous injection (Brand names: Valoid® in UK and Marezine®, Marzine® and Emoquil® in US)).

References

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• British National Formulary 45 March 2003

Antihistamines | Antiemetics