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.
PharmacologyCyclizine 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. Cyclizine exerts a central anticholinergic (antimuscarinic) action.
ContraindicationsIts antimuscarinic action warrants caution in patients with prostatic hypertrophy, urinary retention, glaucoma. Liver disease exacerbates its sedative effects. It cannot be combined with diclofenac, for example in the same syringe or bag of fluids, as a crystallisation reaction occurs. Some opiate-dependent patients combine cyclizine with their methadone dosage, a combination that is known to produce strong psychoactive effects. It is also sold in combination with another opioid dipipanone under the brand name Diconal.
Side effectsCommon (>10%) - Drowsiness, xerostomia (dry mouth)
Rare - Hypersensitivity reactions (bronchospasm, angioedema, anaphylaxis, rashes and photosensitivity reactions), extrapyramidal effects, dizziness, confusion, depression, sleep disturbances, tremor, liver dysfunction.
FormulationsAs 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).