Drug information of Cyclizine

Cyclizine

Drug group: Antiemetic

A histamine H1 antagonist given by mouth or parenterally for the control of postoperative and drug-induced vomiting and in motion sickness.

Mechanism of effect

Emesis or vomiting is controlled by the vomiting centre in the medulla region of the brain, an important part of which is the chemotrigger zone (CTZ). The vomiting centre possesses neurons which are rich in muscarinic cholinergic and histamine containing synapses. These types of neurons are especially involved in transmission from the vestibular apparatus to the vomiting centre.

Motion sickness principally involves overstimulation of these pathways due to various sensory stimuli. Hence the action of cyclizine which acts to block the histamine receptors in the vomiting centre and thus reduce activity along these pathways. Furthermore since cyclizine possesses anti-cholinergic properties as well, the muscarinic receptors are similarly blocked.

Pharmacodynamic

Cyclizine is a piperazine-derivative antihistamine used as an antivertigo/antiemetic agent. Cyclizine is used in the prevention and treatment of nausea, vomiting, and dizziness associated with motion sickness. Additionally, it has been used in the management of vertigo in diseases affecting the vestibular apparatus.

 Although the mechanism by which cyclizine exerts its antiemetic and antivertigo effects has not been fully elucidated, its central anticholinergic properties are partially responsible. The drug depresses labyrinth excitability and vestibular stimulation, and it may affect the medullary chemoreceptor trigger zone. It also possesses anticholinergic, antihistaminic, central nervous system depressant, and local anesthetic effects.

Pharmacokinetics

  • Onset: 30 to 60 minutes, depending on dose
  • Duration: 4 to 6 hr
  • Metabolism: Hepatic
  • Half-life elimination: 14 hr (cyclizine); 24hr (norcyclizine)
  • Excretion: Urine (<1% unchanged)
  • Vd: 17 L/kg

Drug indications

Migraine , Motion sickness

Dosage

Indicated for the prevention and treatment of nausea, vomiting and vertigo associated with motion sickness

adult

50 mg PO taken 30 minutes before departure, may repeat in 4-6 hours if needed, up to 200 mg/day

Pediatric

6-12 years: 25 mg PO up to 3 times/day; not to exceed 75 mg/day

>12 years: 50 mg PO taken 30 minutes before departure, may repeat in 4-6 hr if needed, up to 200 mg/day

Drug contraindications

Asthma , glaucoma , Hypersensitivity

Alerts

May have hypotensive effects, which may be confusing or dangerous in postoperative patients

May produce drowsiness; caution while driving or performing other tasks requiring alertness

Points of recommendation

Avoid driving and doing other tasks or actions that call for you to be alert until you see how cyclizine affects you.

Avoid drinking alcohol while taking cyclizine.

Talk with your doctor before you use other drugs and natural products that slow your actions.

Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using cyclizine while you are pregnant.

Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

If you are taking cyclizine for motion sickness, take 30 minutes before travel.

Pregnancy level

B


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