Description

            Cyclizine hydrochloride

Cyclizine hydrochloride is a piperazine-derivative antihistamine that is used to treat vertigo and nausea. Cyclizine is used to prevent and treat motion sickness symptoms such as nausea, vomiting, and dizziness. It has also been used to treat vertigo caused by disorders of the vestibular apparatus. Although the mechanism by which cyclizine produces its antiemetic and antivertigo actions is not entirely understood, its central anticholinergic characteristics play a role. The medication reduces labyrinth excitability and vestibular stimulation, and it may have an effect on the medullary chemoreceptor trigger zone. It has anticholinergic, antihistaminic, central nervous system depressive, and local anaesthetic properties as well.

Mechanism of action

Vomiting (emesis) is a defensive mechanism that removes irritants or other potentially hazardous chemicals from the upper GI tract. The vomiting centre in the medulla region of the brain, which includes the chemotrigger zone (CTZ), controls emesis or vomiting. The vomiting centre contains neurons with muscarinic cholinergic and histamine-containing connections. These neurons are particularly important in transmitting information from the vestibular apparatus to the vomiting area. Motion sickness is caused mostly by overstimulation of these pathways as a result of numerous sensory stimuli. As a result, cyclizine acts to inhibit histamine receptors in the vomiting centre, reducing activity along these routes. Furthermore, because cyclizine has anti-cholinergic characteristics, the muscarinic receptors are inhibited.

cyclizine hydrochloride dosing information

Usual Pediatric Dose for Motion Sickness:

6 years and older: 25 mg orally every 6 to 8 hours
-Maximum dose: 75 mg/day

Comments:
-For the prevention of travel sickness, patients should take the first dose approximately 1 hour prior to departure or at the onset of symptoms.
-Patients should be cautioned to avoid driving or operating machinery while taking this drug.