What about using cinnarizine for motion sickness?

Cinnarizine for Motion Sickness

Cinnarizine is an effective first-generation antihistamine for motion sickness prevention that works comparably to other antihistamines, but it causes significant sedation and impaired performance, making it unsuitable for anyone operating vehicles or requiring sustained attention. 1, 2, 3

Efficacy Evidence

• Cinnarizine belongs to the class of first-generation antihistamines that are probably more effective than placebo at preventing motion sickness under natural conditions (40% prevention with antihistamines vs 25% with placebo). 1

• In a direct comparison study of helicopter pilots, cinnarizine significantly improved simulator sickness scores from an average of 73.30 to 30.92 after 2 hours (P = 0.012), and was more effective than scopolamine for simulator sickness prevention. 2

• Real-world operational experience from a Pacific Ocean rescue mission showed that cinnarizine (approximately 18mg two to three times daily) provided relief of nausea, vomiting, dizziness, and sensory imbalances in pararescue personnel, with improvement in operational effectiveness. 4

Mechanism of Action

• Cinnarizine is a piperazine derivative with multiple pharmacologic properties: antihistaminic (H1-receptor antagonist), antiserotoninergic, antidopaminergic, and calcium channel-blocking effects. 5, 4

• The antihistaminic effect suppresses the central emetic center to relieve nausea and vomiting associated with motion sickness. 1

Critical Safety Concerns and Contraindications

• Cinnarizine causes significant central nervous system effects including sedation and impaired performance across the therapeutic dose range of 15-45 mg, with effects lasting 5-8 hours after ingestion. 3

• At 15 mg, cinnarizine reduced sleep latencies at 3.5 and 5.0 hours post-ingestion and increased subjective sleepiness at 5.0 and 6.5 hours. 3

• At 30 mg, cinnarizine impaired performance at 5.0,6.5, and 8.0 hours after ingestion with increased sleepiness. 3

• Cinnarizine is absolutely contraindicated for aircrew involved in aircraft control and should be used with extreme caution by anyone performing tasks requiring sustained attention. 3

Adverse Effects Profile

• When compared to placebo, first-generation antihistamines (including cinnarizine) may be more likely to cause sedation (66% vs 44% with placebo, RR 1.51). 1

• In pediatric overdose cases (23 reports from 1972-2004), cinnarizine caused alterations in consciousness ranging from somnolence to stupor and coma, vomiting, extrapyramidal symptoms, hypotonia, and convulsions in young children. 5

• The neurologic complications are explained by both the antihistaminic effect (causing CNS depression and convulsions) and the antidopaminergic effect of cinnarizine. 5

• Common side effects include sedation, weight gain, and abdominal pain, with depression and extrapyramidal symptoms possible particularly in elderly persons (similar to flunarizine, a related calcium-channel blocker). 6

Dosing Considerations

• Typical dosing based on operational use is approximately 18 mg two to three times daily. 4

• The therapeutic dose range is 15-30 mg, though even 15 mg is not free of central nervous system activity. 3

• In pediatric overdose, elimination half-life was calculated at 3.65 hours, with clinical recovery occurring within 10 hours. 5

Clinical Decision Algorithm

For motion sickness prevention, choose cinnarizine only if:

1. The patient will not be operating vehicles, aircraft, or machinery
2. The patient will not be performing tasks requiring sustained attention or alertness
3. The patient has failed or cannot use scopolamine (transdermal patch applied 6-8 hours before travel)
4. The patient has failed or cannot tolerate meclizine (12.5-25 mg three times daily)

Avoid cinnarizine in favor of:

• Scopolamine transdermal patch for most patients requiring alertness 7
• Meclizine for patients with contraindications to scopolamine 7
• Promethazine 12.5-25 mg for severe cases requiring rapid onset 7

Important Caveats

• Long-term use of vestibular suppressant medications like cinnarizine can interfere with central compensation in peripheral vestibular conditions and should be avoided. 7, 8

• Anticholinergic medications (including antihistamines) are an independent risk factor for falls, especially in elderly patients. 7

• Pediatric patients with cinnarizine overdose need observation in a healthcare facility for potential neurologic complications including convulsions, with a delay to onset of clinical effects considered in the observation period. 5