TREATMENT OF MIGRAINE’S ACUTE ATTACK WITH DRUGS: ERGOTAMINE
Some of the most effective remedies are drugs containing ergotamine although, like many other well-known drugs, the way in which this compound worked was unknown for many years.The drug comes from a mould that grows on rye; the name is derived from the French word ‘ergot’ meaning a ‘spur’ because part of the plant resembles a riding spur in shape. Eating bread made from mouldy rye can be poisonous, producing painful blue hands and feet (‘St. Anthony’s Fire’). As a result of such poisoning, whole villages in Eastern Europe were reported to have been visited by the devil and cure was obtained by visiting St. Anthony’s shrine (which was in Egypt and outside the infected area). The use of ergotamine in the treatment of headache was first reported in Germany in 1883. In 1889, Dr. W. Thompson of the United States advised taking fluid extract of ergot by mouth but also suggested that rectal administration could be useful: ‘As nausea is such a general accompaniment of this affection it is prescribed that if either of the doses be vomited it should be taken in an enema of two ounces of water. This medication rarely fails to arrest the attacks.’ After this report, the use of ergot seems to have been forgotten, possibly because of the inconsistent effect of the extracts, until 1906, when an extract from ergot, ergotoxine, was isolated. This was later found to be a mixture of compounds. In 1918 a single compound was isolated – ergotamine – which was initially used to speed up uterine contractions during labour (ergot derivatives are still used in obstetrics). In 1925 ergotamine in its pure form was first used in the treatment of migraine and began to be prescribed widely. But it was not until 1937 that the main cause of the migraine headache was found to be due to blood vessels in the head becoming wider (extracranial vasodilation); and it was then shown that ergotamine worked because it narrowed these blood vessels (vasoconstrictor action). Because the migrainous aura was due to vasoconstriction, it was theoretically worrying to give a powerful vasoconstrictor drug at a time when vasospasm was present in the intracranial circulation. However, although ergotamine may prolong the migraine aura, there is no lessening of cerebral blood flow, possibly because the vessels at this time are less sensitive to the vasoconstrictive action of the drug.
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