cinnarizine

Action and Spectrum

Actions and spectrum: 

cinnarizine is a medication that belongs to the class of calcium channel blockers and antihistamines. Its actions include blocking the histamine H1 receptors, inhibiting calcium influx into smooth muscle cells, and reducing the sensitivity of the vestibular system.

cinnarizine is primarily used for the treatment of motion sickness and vertigo associated with inner ear disorders. It helps alleviate symptoms such as dizziness, nausea, and vomiting. Additionally, cinnarizine may have some vasodilatory effects, potentially improving blood flow to certain organs. 

Drug Interaction

Adverse Reaction

None

Black Box Warning

Black Box Warning: 

cinnarizine does not have any specific black box warning. 

Contraindication / Caution

Contraindication/Caution: 

Contraindication: 

• Hypersensitivity: Individuals who have known hypersensitivity or allergic reactions to cinnarizine or any of its components should not use this medication. 
• Parkinson’s Disease: cinnarizine should be avoided in patients with Parkinson’s disease or parkinsonian symptoms due to the potential risk of worsening these conditions. 
• Severe Hypotension: cinnarizine can cause a drop in blood pressure, and therefore, it is contraindicated in patients with severe hypotension. 
• Pheochromocytoma: cinnarizine should not be used in patients with pheochromocytoma, a rare tumor that can cause high blood pressure. 
• Porphyria: cinnarizine is contraindicated in individuals with porphyria that affect the production of heme, a component of hemoglobin. 

Caution: 

• Cardiovascular Conditions: cinnarizine can cause hypotension (low blood pressure) and may worsen pre-existing cardiovascular conditions such as coronary artery disease, heart failure, or arrhythmias. Close monitoring of blood pressure and cardiovascular function is advised. 
• Elderly Patients: They are more sensitive to the effects of cinnarizine, including sedation and anticholinergic effects. Careful dose titration and monitoring are recommended. 
• Pregnancy and Lactation: cinnarizine should be used with caution in pregnant or breastfeeding women. The safety of cinnarizine in these populations is not well-established, and the potential risks and benefits should be assessed by a healthcare professional. 
• Central Nervous System Depression: cinnarizine may cause drowsiness and impair cognitive and motor function. Patients should be advised to avoid activities that require mental alertness until they know how they respond to the medication.

Comorbidities: 

• Parkinson’s Disease: cinnarizine may worsen the symptoms of Parkinson’s disease due to its anticholinergic properties. It can cause extrapyramidal symptoms, including tremors and rigidity. Caution is needed when using cinnarizine in individuals with Parkinson’s disease. 
• Epilepsy or Seizure Disorders: cinnarizine may lower seizure threshold & may increase the risk of seizures, particularly in individuals with a history of epilepsy or seizure disorders. Close monitoring is necessary, and the use of cinnarizine should be carefully evaluated in these patients. 
• Respiratory Conditions: cinnarizine may cause respiratory depression and should be used cautiously in individuals with respiratory conditions such as COPD or asthma. 
• Hepatic Impairment: cinnarizine is primarily metabolized in the liver, so caution is advised in individuals with hepatic impairment. Dose adjustments or monitoring of liver function may be necessary. 
• Renal Impairment: cinnarizine is primarily excreted by the kidneys, so caution should be exercised in individuals with renal impairment. Dose adjustments or monitoring of renal function may be necessary. 

Pregnancy / Lactation

Pregnancy consideration: pregnancy category: not assigned 

Lactation: excreted into human milk: unknown  

Pregnancy category: 

• Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester. 
• Category B: there was no evidence of risk to the fatuus in animal studies, and there were not enough studies on pregnant women. 
• Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.   
• Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits. 
• Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women. 
• Category N: There is no data available for the drug under this category. 

Pharmacology

Pharmacology: 

cinnarizine is a calcium channel blocker with antihistamine and anti-dopaminergic properties. Its pharmacology is characterized by its ability to block calcium channels, particularly those found in vascular smooth muscle cells. This results in vasodilation and improved blood flow. cinnarizine also acts as an antagonist at histamine H1 receptors, reducing histamine-induced allergic reactions. Additionally, it exhibits anti-dopaminergic activity by blocking dopamine receptors in the basal ganglia and chemoreceptor trigger zone, which helps alleviate symptoms of vertigo and motion sickness.  

Pharmacodynamics: 

• Calcium Channel Blockade: cinnarizine inhibits voltage-gated calcium channels, leading to a reduction in calcium entry into smooth muscle cells and vascular endothelial cells. This results in vasodilation and increased blood flow. 
• Histamine H1 Receptor Antagonism: cinnarizine acts as an antagonist at histamine H1 receptors, blocking the effects of histamine. This helps alleviate symptoms of allergies, such as itching, sneezing, and nasal congestion. 
• Dopamine D2 Receptor Blockade: cinnarizine has a weak antidopaminergic effect, meaning it blocks dopamine D2 receptors. This property is responsible for its antiemetic and anti-motion sickness effects. 
• Anticholinergic Activity: cinnarizine exhibits mild anticholinergic activity, which can lead to drying of secretions and other related effects. 
• Serotonin Receptor Antagonism: cinnarizine has been shown to possess antagonistic effects on certain subtypes of serotonin receptors, particularly 5-HT2 receptors. This may contribute to its antiemetic and anti-vertigo properties. 

Pharmacokinetics: 

Absorption 

cinnarizine is well absorbed after oral administration. The absorption is relatively slow and incomplete, with a bioavailability of about 15-20%. Food intake can delay the absorption but does not significantly affect the overall extent of absorption. 

Distribution 

cinnarizine is extensively distributed throughout the body. It has a high affinity for lipids and is known to accumulate in various tissues, including the brain. It crosses the blood-brain barrier and placenta and is found in breast milk. The drug is highly protein-bound (over 90%), primarily to albumin. 

Metabolism 

cinnarizine undergoes extensive hepatic metabolism. It is metabolized by liver enzyme CYP3A4, with the formation of several metabolites. The major active metabolite is norcinnarizine. The metabolism of cinnarizine can be affected by genetic variations in CYP3A4 activity and drug interactions with CYP3A4 inhibitors or inducers. 

Elimination and excretion 

cinnarizine and its metabolites are eliminated through the bile. A small portion is excreted in the urine. The elimination half-life of cinnarizine is 3-6 hours, but the half-life of the active metabolite, norcinnarizine, is longer at around 20-24 hours. 

Adminstartion

Administration: 

cinnarizine is usually administered orally in the form of tablets or capsules. The specific dosage and frequency of administration will depend on the condition which is being treated and the individual patient’s needs. It is typically recommended to take cinnarizine with meals to minimize gastrointestinal side effects. 

It is important to follow the instructions provided by your healthcare provider or the product label when taking cinnarizine. Should not exceed the recommended dose unless directed by a healthcare professional. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: cinnarizine 

Pronounced: (sin-uh-RI-zine)  

Why do we use cinnarizine? 

• Motion sickness: cinnarizine can help alleviate symptoms of motion sickness, like nausea, vomiting, and dizziness. 
• Vertigo: cinnarizine is effective in reducing the frequency and severity of vertigo episodes associated with conditions like Meniere’s disease and vestibular migraine. 
• Vestibular disorders: cinnarizine is used to manage symptoms of vestibular disorders characterized by balance and coordination problems. 
• Tinnitus: cinnarizine may be prescribed to help reduce the intensity and frequency of tinnitus (ringing in the ears).