What are the indications and contraindications for Sibelium (Flunarizine)?

Sibelium (Flunarizine): Indications and Contraindications

Primary Indication

Flunarizine is indicated as a second-line preventive medication for migraine prophylaxis at a dose of 5-10 mg oral once daily. 1

Additional Indications

• Vertigo of peripheral or central origin: Flunarizine demonstrates proven efficacy in treating vertigo and associated symptoms, with rapid improvement of dizziness and unsteadiness 2, 3
• Adjunctive therapy for refractory epilepsy: Effective as "add-on" treatment for reducing seizure frequency in patients with partial or generalized epilepsy resistant to conventional antiepileptic drugs 2
• Benign paroxysmal positional vertigo (BPPV): One study showed 94.2% symptom resolution at 6 months, though less effective than physical maneuvers 1

Migraine Prevention Context

Flunarizine is positioned as a second-line agent in migraine prevention guidelines, after first-line options including beta-blockers (propranolol, metoprolol), candesartan, and topiramate 1. The drug has proven efficacy comparable to pizotifen, methysergide, and other established migraine preventive agents 1, 4, 2.

Absolute Contraindications

The primary contraindications for flunarizine are:

• Parkinsonism or pre-existing movement disorders 1
• Depression or history of depression 1

Critical Safety Considerations

Flunarizine can cause extrapyramidal symptoms and depression, particularly in elderly patients 1. These movement disorders are similar to those observed with neuroleptics, including orofacial dyskinesia, Parkinsonism, and postural tremor 5. One study specifically demonstrated that flunarizine may worsen symptoms in elderly patients with essential tremor, excluding its use in this population 5.

Common Adverse Effects

The most frequently reported adverse events include:

• Sedation/drowsiness (can be minimized by evening dosing) 1, 4
• Weight gain 1, 4
• Abdominal pain 1

Dosing Strategy to Minimize Side Effects

Given flunarizine's very long half-life (7.3 ± 3.3 days), once-daily evening dosing minimizes drowsiness 4, 6. Steady-state concentrations are reached after approximately 5 half-lives (roughly 5 weeks), so therapeutic effects may take 2-3 months to fully manifest 1, 6.

Special Populations

Elderly Patients

Exercise particular caution in elderly patients due to increased risk of extrapyramidal symptoms and depression 1. However, pharmacokinetic studies show that elderly multimorbid patients (mean age 76 years) demonstrate essentially identical kinetics to younger patients, with no cumulation or enzyme induction during long-term treatment 6.

Pregnancy and Lactation

While not explicitly contraindicated in the guidelines reviewed, flunarizine is not mentioned among recommended migraine preventive agents during pregnancy, where propranolol or amitriptyline under specialist supervision are preferred 1.

Clinical Pearls

• Therapeutic trial duration: Allow 2-3 months for full clinical benefit before determining efficacy 1
• Availability: Flunarizine is commonly used in countries where it is available but is not FDA-approved in the United States 1
• Mechanism: Acts as a selective calcium channel blocker (Class IV calcium antagonist) with direct labyrinthine depressor activity and vasospecific action 4, 6