Cinnarizine (Cinnopar) Side Effects
Cinnarizine carries a significant risk of drug-induced parkinsonism in elderly patients, which may persist long-term even after discontinuation, along with common dose-dependent CNS depression, drowsiness, and gastrointestinal symptoms. 1
Neurological Side Effects
Extrapyramidal Symptoms and Parkinsonism
- Drug-induced parkinsonism is the most serious adverse effect, particularly in elderly patients exposed to cinnarizine for extended periods 1
- Long-term prognosis is concerning: None of the elderly patients in a 7-year follow-up study showed full recovery of extrapyramidal signs after drug discontinuation, contradicting earlier optimistic reports 1
- Two main clinical patterns emerge: "remittent" parkinsonism and "persistent non-progressive" parkinsonism, with rare cases progressing to permanent parkinsonian syndrome 1
- The risk appears unrelated to total drug exposure duration, cumulative dosage, or age at onset 1
Central Nervous System Depression
- Somnolence and stupor occur commonly, particularly in overdose situations where CNS depression can progress from drowsiness to stupor and coma 2
- Convulsions have been documented in young children following overdose, likely related to cinnarizine's antihistaminic and antidopaminergic properties 2
- Mild somnolence affects approximately 26% of patients (5 out of 19) at standard therapeutic doses 3
- Jitteriness, wide-based gait, and twitching can occur, particularly at supratherapeutic doses 2
Common Dose-Dependent Side Effects
Gastrointestinal Symptoms
- Vomiting occurs in overdose situations and occasionally at therapeutic doses 2
- Transient abdominal pain affects approximately 11% of patients (2 out of 19) 3
Other Adverse Effects
- Slight headache occurs in approximately 11% of patients (2 out of 19) 3
- Hypotonia has been reported in overdose cases 2
Special Populations and Risk Factors
Elderly Patients
- Elderly patients face substantially higher risk for extrapyramidal symptoms and drug-induced parkinsonism 1
- Pre-existing neurological conditions do not predict which patients will develop persistent versus remittent parkinsonism 1
- Family history of essential tremor or parkinsonism does not correlate with clinical outcome patterns 1
Pediatric Overdose
- Neurological complications predominate in pediatric overdose, including alterations in consciousness, vomiting, extrapyramidal symptoms, and convulsions 2
- Serum levels can reach 26.9 times therapeutic adult levels in pediatric overdose, with an elimination half-life of 3.65 hours 2
- Notably, cardiovascular complications (bradycardia, hemodynamic instability) are absent despite cinnarizine's calcium channel-blocking properties 2
Clinical Monitoring Recommendations
Observation Requirements
- Patients with cinnarizine overdose require observation in a healthcare facility for potential neurologic complications, with particular attention to delayed onset of clinical effects 2
- Monitor elderly patients closely for early signs of extrapyramidal symptoms during chronic therapy 1
- Treatment is symptomatic; no specific antidote exists 2
Therapeutic Context and Safety Profile
Overall Tolerability
- At standard doses (75 mg twice daily), cinnarizine is generally well tolerated with minor side effects 3, 4
- No serious adverse events were observed in a 14-week prophylactic migraine trial of 60 patients 4
- Temporary vestibular nystagmus depression occurs at higher single doses (150 mg) in healthy volunteers 3
Critical Pitfall to Avoid
Do not dismiss early extrapyramidal symptoms in elderly patients as benign or fully reversible—the evidence clearly demonstrates that drug-induced parkinsonism from cinnarizine frequently persists long-term despite drug discontinuation, requiring early recognition and immediate cessation 1