Sibelium, with the active ingredient flunarizine dihydrochloride, represents a cornerstone in the prophylactic management of migraine. As a selective calcium channel blocker, it modulates vascular tone and neuronal excitability, targeting the underlying pathophysiology of migraine attacks rather than merely addressing acute symptoms. This comprehensive profile is designed for healthcare professionals to understand its mechanism, appropriate application, and clinical considerations for optimizing patient outcomes in chronic migraine prophylaxis.

Features

• Active Ingredient: Flunarizine dihydrochloride.
• Pharmacological Class: Selective calcium entry blocker with calmodulin binding properties.
• Formulation: Typically available in 5mg and 10mg tablet formulations.
• Mechanism of Action: Inhibits calcium influx into vascular smooth muscle cells and neurons; also exhibits antihistaminic (H1) and dopaminergic activity.
• Half-life: Approximately 18 days, allowing for once-daily dosing and stable plasma concentrations.
• Bioavailability: High oral bioavailability, not significantly affected by food.

Benefits

• Reduces Migraine Frequency and Severity: Clinically proven to significantly decrease the number of monthly migraine days and the intensity of attacks.
• Prophylactic Efficacy: Offers preventive treatment, helping to break the cycle of frequent migraines and reduce reliance on acute abortive medications.
• Improved Quality of Life: By preventing attacks, patients often experience less disability, fewer missed workdays, and reduced overall healthcare utilization.
• Once-Daily Dosing: The long half-life supports a simple dosing regimen, enhancing patient adherence compared to multiple-daily-dose prophylactics.
• Vestibular Symptom Management: Its action on calcium channels in the inner ear can provide benefit for patients experiencing migraine-associated vertigo.

Common use

Sibelium (flunarizine) is primarily indicated for the prophylaxis of migraine headache. It is not intended for the acute treatment of a migraine attack. Its use is considered in patients experiencing frequent or severe migraines (e.g., two or more debilitating attacks per month) where a preventive strategy is warranted. It may also be utilized off-label in the management of other conditions such as vertigo of peripheral vestibular origin and adjunct therapy in epilepsy, based on a clinician’s judgment.

Dosage and direction

The dosage must be individualized based on patient response and tolerance. Therapy is typically initiated at a low dose and titrated upwards.

• Adults (Migraine Prophylaxis): The recommended starting dose is 10 mg once daily, taken in the evening to mitigate potential drowsiness. For elderly patients or those of low body weight, a starting dose of 5 mg daily may be appropriate.
• Maintenance: After the initial period, the dose may be adjusted. For many patients, a maintenance dose of 10 mg once daily is effective. In some cases, a reduction to 5 mg daily may be sufficient for long-term control.
• Administration: Tablets should be swallowed whole with a glass of water, with or without food.
• Duration: A trial period of at least 2-3 months is usually necessary to adequately assess therapeutic efficacy. Long-term treatment should be re-evaluated at regular intervals.

Precautions

• Extrapyramidal Symptoms: Flunarizine can rarely induce or exacerbate parkinsonism and other extrapyramidal symptoms, particularly in elderly patients. Monitor for tremor, rigidity, akathisia, and mask-like facies.
• Depression: Patients with a history of depression should be closely monitored, as flunarizine has been associated with the onset or worsening of depressive symptoms.
• Drowsiness and Sedation: May cause significant drowsiness, especially at the beginning of therapy. Patients should be cautioned about operating machinery or driving until their response is known.
• Weight Gain: A moderate increase in body weight is a commonly reported side effect; dietary advice should be given.
• Pregnancy and Lactation: The use of Sibelium during pregnancy is not recommended unless the potential benefit justifies the potential risk to the fetus. It is excreted in breast milk; a decision should be made to discontinue nursing or discontinue the drug.
• Renal/Hepatic Impairment: Use with caution in patients with severe hepatic or renal impairment, as pharmacokinetics may be altered.

Contraindications

Sibelium is contraindicated in patients with:

• Known hypersensitivity to flunarizine dihydrochloride or any of the excipients in the formulation.
• History of depressive illness, or currently presenting with symptoms of depression.
• Pre-existing extrapyramidal disorders, such as Parkinson’s disease.
• Severe hepatic impairment (e.g., Child-Pugh class C).

Possible side effect

Side effects are often dose-dependent and may diminish with continued treatment or dose reduction.

• Very Common (≥1/10): Drowsiness, fatigue, weight increased.
• Common (≥1/100 to <1/10): Depression, insomnia, nausea, stomach pain, dry mouth, muscle aches.
• Uncommon (≥1/1,000 to <1/100): Extrapyramidal symptoms (e.g., tremor, rigidity, akathisia), galactorrhea, breast enlargement, skin rash.
• Rare (≥1/10,000 to <1/1,000): Bradycardia, palpitations.

Drug interaction

• CNS Depressants: Concomitant use with alcohol, sedatives, hypnotics, antipsychotics, or other CNS depressants may potentiate sedative effects.
• Antihypertensives: May potentiate the effect of other blood pressure-lowering agents, increasing the risk of hypotension.
• Dopamine Antagonists: Concurrent use with antipsychotics (e.g., haloperidol) or antiemetics (e.g., metoclopramide) may increase the risk of extrapyramidal symptoms.
• Enzyme Inducers/Inhibitors: Strong inducers of CYP enzymes (e.g., rifampicin, carbamazepine) may decrease flunarizine plasma levels. Strong inhibitors may increase them, though data is limited.

Missed dose

If a dose is missed, it should be taken as soon as remembered on the same day. If it is nearly time for the next scheduled dose, the missed dose should be skipped. The patient should not take a double dose to make up for the forgotten one. Maintaining the regular dosing schedule is paramount.

Overdose

• Symptoms: Overdose would be expected to produce exaggerated pharmacological effects, including severe drowsiness, sedation, coma, hypotension, bradycardia, and agitation. Extrapyramidal symptoms may be pronounced.
• Management: There is no specific antidote. Treatment is supportive and symptomatic. Gastric lavage may be considered if ingestion was recent. Vital signs, including ECG and blood pressure, must be monitored continuously. Management of hypotension and bradycardia with appropriate agents may be required.

Storage

• Store below 30°C (86°F).
• Keep the blister strips in the outer carton to protect from light and moisture.
• Keep out of the sight and reach of children.
• Do not use after the expiration date printed on the packaging.

Disclaimer

This information is intended for educational purposes and for use by qualified healthcare professionals only. It is a summary and does not include all possible information about this product. It does not constitute medical advice. The prescribing healthcare professional is responsible for determining the appropriate diagnosis, treatment, and dosage for each individual patient, based on their professional judgment and a complete assessment of the patient’s condition. Always refer to the full official prescribing information provided by the local regulatory authority or product manufacturer before initiating treatment.

Reviews

• “As a neurologist, I find Sibelium to be a valuable second-line option for patients who do not tolerate beta-blockers. The once-daily dosing is a significant advantage for adherence. I am always mindful of monitoring for weight gain and mood changes.” – Dr. A. Sharma, Neurologist
• “It transformed my patient’s life. From 15 migraine days a month down to 2-3. The initial drowsiness was challenging but subsided after two weeks. A game-changer for her chronic condition.” – Clinical Nurse Specialist, Headache Clinic
• “Effective for prophylaxis, but the side effect profile requires careful patient selection and ongoing dialogue. Not a first-choice for patients with a predisposition to depression.” – Head of Pharmacology, University Hospital
• “A well-established drug in our arsenal. Its benefit in vestibular migraine is particularly noteworthy. Requires patience during the titration phase to find the minimal effective dose.” – Consultant ENT Surgeon