This updated Medicines Q&A evaluates the available evidence on the use of verapamil for the prevention of cluster headache
- A cluster headache consists of attacks of severe unilateral pain that is felt in, behind or around the eye or temple but may spread to other areas of the head.
- Attacks can be classified as episodic or chronic depending on frequency and remission periods.
- Preventive treatment is required as symptomatic treatment alone will rarely achieve adequate control.
- Calcium antagonists block entry of calcium ions into smooth muscle. This reduces blood vessel dilation which is responsible for the severe pain.
- Verapamil is considered the current drug of choice for prevention of episodic and chronic cluster headache. A dose of 360mg daily has been shown to be efficacious in some studies, although sometimes doses of up to 960mg daily is required. Standard release preparations are believed to be more useful than modified release formulations.
- There is a high incidence of heart block and bradycardia with verapamil that can develop with initiation of therapy, increases in dose and during stable dose therapy so electrocardiograms (ECG) should be undertaken
- The efficacy of verapamil in preventing cluster headaches has been demonstrated in both non-randomised and randomised controlled trials versus placebo and other medicines used for prophylaxis.
- Verapamil is highly effective at preventing episodic cluster headaches, although patients with chronic cluster headache have a poorer response.
- Patients with chronic cluster headache may require indefinite prophylaxis. The length of prophylaxis for episodic cluster headache depends on the length of the cluster.