Flunarizine

Flunarizine is a selective calcium entry blocker with additional antihistamine activity. By limiting the flow of calcium into nerve and blood vessel cells it is thought to make the brain less prone to the chain of events that triggers a migraine. It does not stop an attack that has already started; instead it is a preventive treatment, taken daily to cut the number and severity of attacks. UK headache specialists regard it as an option for migraine prophylaxis, usually once better-established preventives such as propranolol, amitriptyline or topiramate have not worked or are unsuitable. Specialists sometimes also use it for vestibular migraine, where dizziness is a prominent feature.

The product is listed in two strengths, 5 mg and 10 mg, each available in packs of 30, 60, 90, 120 or 180. The lower strength gives room for a gentler start or for older people, who are normally kept on half the usual adult amount.

The usual adult dose is 10 mg once a day, taken in the evening because drowsiness is a common effect. People over 65 generally take 5 mg. Benefit builds up gradually, so a fair trial lasts around two to three months before deciding whether it is worthwhile. If depression, movement problems or significant tiredness appear, treatment is stopped. Where it does help, specialists review it regularly and often plan breaks, since the risk of some adverse effects grows with continuous long-term use. Keeping a headache diary makes it easier to judge whether attacks have genuinely become less frequent. A useful diary records the date, how long each attack lasted, how severe it was and which painkillers or triptans were needed. Overuse of acute pain relief can itself keep headaches going, so a specialist will often look at this before judging whether a preventive has failed. Regular meals, enough sleep, steady caffeine intake and staying well hydrated support any preventive treatment.

No flunarizine product holds a UK marketing authorisation, and it does not appear in the BNF as a licensed medicine. Headache clinics can still obtain it as an unlicensed import, in which case it is prescribed on the clinician’s own responsibility and treated in practice as a prescription-only medicine. The doctor or prescriber decides whether it is an appropriate choice for a particular patient.

It is unsuitable for anyone with a history of depression, because low mood is a recognised effect, and for people with Parkinson’s disease or other movement disorders, which it can worsen. Alcohol, sedating antihistamines, sleeping tablets and other medicines that cause drowsiness add to its sedative effect. Enzyme-inducing anti-epileptics such as carbamazepine and phenytoin can lower its blood levels. It is generally avoided in pregnancy and while breastfeeding unless a specialist advises otherwise.

Sleepiness, tiredness, increased appetite and weight gain are the effects people mention most often. Some notice heartburn, nausea, a dry mouth or muscle aches. Low mood or depression, and extrapyramidal symptoms such as tremor, stiffness or slowed movement, are the most important reasons to stop, and older adults are more vulnerable to them. Because Flunarizine can impair alertness, take care with driving until you know how it affects you, and report suspected side effects through the Yellow Card scheme.