Usage
Cinnarizine is primarily prescribed for the symptomatic treatment of vertigo, nausea, vomiting, tinnitus, and nystagmus associated with various vestibular (inner ear) disorders, including Ménière’s disease and labyrinthitis. It is also used for the prophylaxis and treatment of motion sickness and, in some instances, for peripheral vascular disorders like Raynaud’s phenomenon. Cinnarizine is classified as an antihistamine with additional calcium channel blocking properties. It acts by suppressing the excitability of the vestibular system within the inner ear.
Alternate Names
While Cinnarizine itself is the generic name recognized internationally, it is marketed under various brand names such as Cinarizin, Cinna, Stugeron, and others depending on the region.
How It Works
Pharmacodynamics: Cinnarizine primarily exerts its therapeutic effects by acting as a histamine H1 receptor antagonist and a calcium channel blocker. It works by reducing the activity of the vestibular system in the inner ear, thereby alleviating symptoms like vertigo, nausea, and vomiting. As a calcium channel blocker, it inhibits calcium influx into vascular smooth muscle cells, causing vasodilation and improving blood flow in peripheral vessels. It doesn’t affect blood pressure significantly.
Pharmacokinetics: Cinnarizine is well-absorbed orally and reaches peak plasma concentrations within 1-3 hours. It is extensively metabolized in the liver, primarily via CYP450 enzymes, and eliminated through both renal and hepatic routes. The elimination half-life is approximately 4 hours.
Mode of Action: Cinnarizine binds to H1 histamine receptors, blocking the action of histamine in the vestibular system. This reduces the excitability of the vestibular nerve and the associated symptoms of vertigo, nausea, and vomiting. By blocking calcium channels, it decreases the contractility of vascular smooth muscle, leading to vasodilation. The precise mechanism for its efficacy in treating vertigo and motion sickness is not fully elucidated but is attributed to the above combination.
Dosage
Standard Dosage
Adults:
- Vertigo and Vestibular Disorders: 25 mg three times daily or 75 mg once daily.
- Motion Sickness: 25 mg two hours before travel, then 15 mg every eight hours as needed.
Children (5-12 years):
- Vertigo and Vestibular Disorders: 15 mg three times daily.
- Motion Sickness: 15 mg two hours before travel, then 7.5 mg every eight hours as needed.
- Children (12-17 years): usually prescribed an adult dose
Special Cases:
- Elderly Patients: No dose adjustment is typically necessary, but start at a low dose and increase gradually as needed.
- Patients with Renal Impairment: Use with caution in mild to moderate impairment. Contraindicated in severe renal impairment (creatinine clearance ≤ 25 mL/min).
- Patients with Hepatic Dysfunction: Use with caution in mild to moderate impairment. Contraindicated in severe hepatic impairment.
- Patients with Comorbid Conditions: Caution is advised in patients with Parkinson’s disease or glaucoma.
Clinical Use Cases
Cinnarizine’s use in specific clinical settings like intubation, surgical procedures, mechanical ventilation, ICU use, and emergency situations is not routinely indicated. Its primary clinical use is for the management of vertigo and motion sickness.
Dosage Adjustments
Dose adjustments should be made based on the patient’s individual response and tolerance. Renal and hepatic impairment necessitate careful consideration and potential dose reduction or avoidance. Close monitoring for adverse effects is recommended, especially in elderly patients.
Side Effects
Common Side Effects:
Drowsiness, fatigue, dry mouth, headache, gastrointestinal discomfort, weight gain.
Rare but Serious Side Effects:
Allergic reactions (skin rash, itching, swelling), extrapyramidal symptoms (tremors, rigidity), cholestatic jaundice, and lupus-like syndrome.
Long-Term Effects:
Chronic use may potentially lead to tardive dyskinesia and other movement disorders in susceptible individuals. Regular monitoring is advised for long-term use.
Contraindications
Hypersensitivity to cinnarizine, severe hepatic impairment, severe renal impairment (creatinine clearance ≤ 25 mL/min), porphyria, Parkinson’s disease (relative contraindication, assess risk/benefit).
Drug Interactions
Alcohol, CNS depressants (sedatives, hypnotics, opioids), tricyclic antidepressants, and MAO inhibitors may potentiate the sedative effects of cinnarizine. Concomitant use of these medications should be approached cautiously.
Pregnancy and Breastfeeding
Cinnarizine is generally avoided during pregnancy, especially in the first trimester, due to limited safety data. Its use during breastfeeding is also not recommended as it is excreted in breast milk.
Drug Profile Summary
- Mechanism of Action: Histamine H1 receptor antagonist, calcium channel blocker.
- Side Effects: Drowsiness, fatigue, dry mouth, headache, GI discomfort.
- Contraindications: Hypersensitivity, severe hepatic/renal impairment.
- Drug Interactions: Alcohol, CNS depressants, tricyclic antidepressants.
- Pregnancy & Breastfeeding: Generally avoided.
- Dosage: Adults: 25 mg TID or 75 mg OD; Children: Age-dependent dosing.
- Monitoring Parameters: Liver function tests, renal function tests for prolonged use.
Popular Combinations
Cinnarizine is often combined with dimenhydrinate for enhanced anti-vertigo effects. However, this combination may increase the risk of drowsiness and other side effects.
Precautions
Caution in elderly patients, patients with renal or hepatic impairment, and those with Parkinson’s disease or glaucoma. Avoid alcohol and activities requiring alertness.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Cinnarizine?
A: Adults: 25 mg three times daily or 75 mg once daily. Children: Age-dependent dosing.
Q2: How does Cinnarizine work?
A: It acts as an antihistamine and calcium channel blocker, reducing vestibular system excitability and improving peripheral blood flow.
Q3: What are the common side effects of Cinnarizine?
A: Drowsiness, dry mouth, fatigue, headache, gastrointestinal discomfort.
Q4: Can Cinnarizine be used during pregnancy?
A: Generally avoided, especially in the first trimester, due to limited safety data.
Q5: What are the contraindications for Cinnarizine?
A: Hypersensitivity, severe hepatic/renal impairment, porphyria.
Q6: Does Cinnarizine interact with other medications?
A: Yes, it can interact with alcohol, CNS depressants, and tricyclic antidepressants.
Q7: Can Cinnarizine be used in children?
A: Yes, with age-appropriate dose adjustments.
Q8: How long can a patient take Cinnarizine?
A: For vertigo, it can be used for several months under medical supervision. For motion sickness, only as needed during travel.
Q9: What if a dose is missed?
A: Take as soon as remembered, unless close to the next scheduled dose. Do not double the dose.
Q10: What precautions should be taken while using Cinnarizine?
A: Avoid alcohol and activities requiring alertness, especially during initial treatment. Monitor for potential drug interactions.
