Flunarizine is a prescription medication classified as a calcium channel blocker. This drug is available for oral administration in tablet or capsule form. While used in many countries, it is not approved for use by the U.S. Food and Drug Administration (FDA). Flunarizine is primarily prescribed for specific neurological and vascular conditions.
Medical Uses of Flunarizine
The primary application for flunarizine is in migraine prophylaxis. This means the medication is taken regularly, not to treat a migraine attack that is already happening, but to reduce the frequency and severity of future episodes.
Beyond migraine prevention, flunarizine is also used to manage vertigo, which is a sensation of spinning, that originates from either central or peripheral vestibular disorders. The medication helps to alleviate symptoms associated with these balance issues. Another application is in treating occlusive peripheral vascular disease, a condition affecting blood circulation in the limbs.
How Flunarizine Works
Flunarizine functions as a selective calcium channel blocker. It works by inhibiting the influx of calcium into cells through specific channels in the cellular membrane. This action is particularly relevant in smooth muscle cells of blood vessels, where a decrease in intracellular calcium leads to the relaxation and dilation of arteries. This process helps to prevent the excessive constriction of blood vessels in the brain, a factor often associated with the onset of migraines.
By preventing this cellular calcium overload, the medication helps stabilize neuronal activity, which is the mechanism that reduces the frequency of migraine attacks. In addition to its primary function, flunarizine also exhibits some antihistamine and sedative properties, which contribute to its overall effects.
Potential Side Effects and Risks
The use of flunarizine is associated with several potential side effects. Among the most commonly reported adverse effects are drowsiness or fatigue and weight gain, which is often linked to an increased appetite. These effects are generally manageable but should be monitored by a patient and their doctor.
More serious risks involve the central nervous system. A significant concern is the potential for extrapyramidal symptoms, which are movement disorders. These can manifest as parkinsonism, with symptoms that mimic Parkinson’s disease, or tardive dyskinesia, characterized by involuntary, repetitive body movements.
Other reported side effects include:
- Nausea
- Heartburn
- Dry mouth
- Insomnia
In some cases, particularly in women taking oral contraceptives, there have been reports of galactorrhea, which is the production of milk from the breasts unrelated to pregnancy or nursing. Any new or worsening symptoms experienced while taking flunarizine should be promptly reported to a healthcare provider.
Important Considerations for Use
The adult dosage for migraine prophylaxis is 5 to 10 mg taken once daily, in the evening to minimize the impact of its sedative effects. The medication can be taken with or without food. It is not recommended for use in children under 18 years of age, as its safety and efficacy in this population have not been established.
Certain individuals should not take this medication. It is contraindicated for those with a known hypersensitivity to the drug, a history of depression, or pre-existing symptoms of Parkinson’s disease or other extrapyramidal disorders. Caution is also advised for patients with liver impairment, as the drug is extensively metabolized by the liver.
Patients should be aware of potential drug interactions. Combining flunarizine with alcohol or other central nervous system depressants can lead to excessive sedation and is advised against. The medication can also interact with drugs that affect liver enzymes, such as carbamazepine and phenytoin, which may alter its effectiveness. Given its potential to cause drowsiness, patients are advised not to drive or operate heavy machinery until they know how the drug affects them.