Cyclizine

Question 1

What drug class is Cyclizine?

Answer 1

H1 receptor antagonist

Question 2

What are the common indications of Cyclizine?

Answer 2

• Motion sickness (long journeys where don’t need to drive - sedation effects)
• Gut problems causing nausea
• Post-op nausea

Question 3

What is the mechanism of action of Cyclizine?

Answer 3

Acts on the vestibular nuclei

Inhibits histaminergic signals from the vestibular system to the CTZ (chemoreceptor trigger zone)

Question 4

What are the common adverse reactions of Cyclizine?

Answer 4

• Sedation
• Excitation
• Antimuscarinic symptoms - dry mouth, constipation, urinary retention
• Cardiac toxicity - prolongs QT interval

Question 5

What are the common drug-drug interactions of Cyclizine?

Answer 5

• Sedative anti-psychiatric drugs
• Anticholinergics
• Antiarrhymitics that prolong the QT interval e.g. amiodarone, flecainide, sotalol