Flunarizine, sold under the brand name Sibelium among others, is a drug classified as a calcium antagonist which is used for various indications.

Elimination half life varies widely between individuals and is about 5 to 15 hours after a single dose, and 18 to 19 days on average when given daily.

[3][5] Flunarizine is a diphenylmethylpiperazine derivative related to the antihistamines hydroxyzine and cinnarizine (an older molecule also discovered by Janssen).

Flunarizine may help to reduce the severity and duration of attacks of paralysis associated with the more serious form of alternating hemiplegia, as well as being effective in rapid onset dystonia-parkinsonism (RDP).

[6][7] Flunarizine extended motor neuron survival in spinal cord, protected skeletal muscles from cell death and atrophy and extended survival by 40% in an animal model of spinal muscular atrophy.