ANTIMIGRAINE DRUGS are used to treat migraine attacks, which constitute a specific clinically recognized form of headache. Attacks vary in form, but common characteristics include: throbbing in the head confined to one side only (unilateral headache), nausea and vomiting, and a forewarning of the attack (an aura) consisting of visual disturbances and weakness or numbness of the limbs. Drugs are used to help migraine sufferers (and the related state called ‘cluster headache’) in two quite distinct ways.
One group of drugs is given chronically, and helps to prevent attacks (prophylactic use): such as CALCIUM-CHANNEL BLOCKERS. e.g. nifedipine and verapamil; the β-blockers, e.g. metoprolol, nadolol, propranolol and timolol (see β-ADRENOCEPTOR ANTAGONISTS); and also certain vasoactive drugs, including cyproheptadine and the ergot alkaloid methysergide. All these drugs affect blood vessels. In migraine attacks, cerebral vessels are thought to constrict before an attack, then dilate, causing pain during the attack.
A second group of drugs may be used to treat acute attacks, either at the stage of the prewarning aura, or during the attack stage itself; and here speed of administration and subsequent absorption of the drug into the body is an all-important factor. Drugs that affect blood vessels can also be used at the acute stage, including the time-honoured drug ergotamine. The recently introduced sumatriptan and zolmitriptan (5-HT1B/D partial agonists) can be self-injected (or given intranasally) to achieve a rapid onset of action: see 5-HYDROXYTRYPTAMINE RECEPTOR AGONISTS.
A number of ANALGESICS can be used to offset the pain of the attack, including aspirin, codeine and paracetamol, and these are often incorporated into compound preparations together with a variety of other drugs and drug types, e.g. caffeine, buclizine, doxylamine, isometheptene, pizotifen. Sometimes drugs with antinauseant or ANTIEMETIC properties are included, e.g. cyclizine and metoclopramide.
New initiatives in developing migraine treatments include the use of TACHYKININ RECEPTOR ANTAGONISTS and CALCITONIN GENE-RELATED PEPTIDE RECEPTOR ANTAGONISTS.