MIGRAINE: TREATMENT OF THE EXISTING ATTACK

Migraine is a syndrome which involves a lot more than just the brain. One of the things it does is stop the absorption of substances from the stomach (in addition to making the patient nauseous and sick). Anything that is in the stomach that isn’t vomited up is likely to stay there unabsorbed for a long time.

Now we’ve found that we can reverse this with certain types of anti-vomiling drugs. Metoclopramide is one, domperidone is another. These are anti-nausea drugs that also stabilise the muscle activity within the gut, on which it can have a most dramatic effect. Giving a small dose of metoclopramide together with paracetamol or aspirin, allows the pain-killer to be absorbed across the stomach wall and – hey, presto! – in many cases the migraine attack is aborted. Metoclopramide and domperidone also have the extra advantage of being anti-vomiting agenls, damping down the vomiting centre and reducing what is probably the second most unpleasant aspect of migraine, after the headache.

The use of metoclopramide and similar drugs has revolutionised many aspects of migraine therapy, and has certainly reduced the need for the heavy morphine-based drugs. At the first sign of an attack a sufferer may take a tablet of metoclopramide together with a couple of tablets of paracetamol or aspirin (or, a combination drug combining both of them) and, with a bit of luck, the attack may be halted.

Migraleve Pink tablets contain an anti-vomiting agent of a different type: Migraleve Yellow tablets (the follow-on tablets) don’t contain painkillers.

The most important aspect of treating an attack is to start taking the medicines early. Nipping it in the bud is one of the most effective ways of dealing with an impending attack; leaving it for several hours may be too late.

There is a wide variety of drugs to select from, and different doctors will have different ideas about the relative importance of each group. Not all drugs are safe to use for children.

The five groups of drugs used to treat an attack are: analgesics, anti-vomiting agents, ergotamine, sedatives and the 5-HT stimulants.

• Analgesics. There’s no great virtue in taking strong analgesics when simple ones will do, and often paracetamol and/or aspirin are perfectly acceptable, provided that they are absorbed into the bloodstream. Aspirin has the additional advantage that it helps to reduce the stickiness of platelets in the blood; and, as these may have a role in the migraine attack, aspirin may be of added benefit. Don’t give aspirin to children, and don’t use it in pregnancy, nor if you have stomach ulcers or are on anticoagulants or steroids.

If simple analgesics like these don’t work your doctor may well prescribe something stronger, such as codeine, dihydrocodeine or coproxamol: in the last resort it may still be necessary to use pethidine, morphine, diamorphine, or pentazocine. Where you are continuing to vomit it may be necessary to give these very strong drugs by injection.

Anti-vomiting Drugs. We’ve already dealt with the anti-nausea drugs. These have two effects: reducing vomiting and nausea, and allowing the absorption of other drugs. Obviously, if there is vomiting already then these agents won’t work and will need to be given by injection or suppository.

Ergotamine. Ergotamine is a potent vaso-constrictor (causing blood vessels to clamp tip tightly) which, bearing in mind that in migraine the blood vessels are often dilated, may be the reason why it helps. However more recent work suggests that its action on blood vessels is a lot more complex than this. Ergotamine isn’t absorbed very well in tablet form so it’s often used as a suppository, taken under the tongue or inhaled, using a pressurised inhaler. Caffeine helps the absorption of ergotamine, and is often combined with it. The big problem with the use of ergotamine is that the effective dose is very near the toxic dose. Do not increase the dose of ergolamine beyond what your doctor has prescribed, or you could lose the blood supply to your extremities, causing gangrene.

Also, ergotamine must neverhe given to a pregnant woman because it can cause the most violent contractions in the womb, leading either to a premature delivery or to suffocation of the baby within the womb. Ergotamine should also not be used in those with heart disease or circulation problems. Ergotamine mustn’t be used too regularly – there is an crgotamine-abuse syndrome, in which the ergotamine itself causes headaches. Ergotamine headaches are unlike migraines, being more of a generalised dull headache.

•    Sedatives. Sedatives are sometimes useful in aborting an attack early on. If you are able to relax and go to sleep you may wake up headache-free, and this is particularly useful when stress is a triggering factor. Common sedatives include the benzodiazepine tranquillisers: diazepam, chlordizepoxide etc. but there are others, such as chlorpromazine.

However, many anti-migraine drugs contain caffeine, which will have the opposite effect! It may be better to avoid caffeine-containing drugs if your migraines are linked to stress or anxiety.

•    5-HT Stimulants (agonists). Transmitter chemicals allow messages to pass from nerve to nerve in the body. One of these chemicals is a substance called 5-HT, otherwise known as serotonin. 5-HT seems to have an important part to play in the workings of the brain, though the exact relationship between 5-HT levels and problems such as anxiety, depression, eating and migraines is anything but simple. However, we do know that 5-HT seems to be reduced in those suffering from depression, and that it is intimately bound up with eating and appetite, and in migraine. There are three different types of 5-HT receptors, and the ones involved in depression are probably not the same type as the ones involved in migraine.

There are various ways to interfere with the workings of these brain chemicals. They can be blocked or their effects can be increased. One particular group of drugs seems to be able to help in the established attack of migraine. These are called 5-HT agonists or stimulants, and they stimulate the 5-HT receptors, just like 5-HT does in its natural role.

However, it isn’t a question of simply giving extra 5-HT and thereby preventing migraines; rather, we actually prevent the onset of migraine attacks by using 5-HT blocker drugs, such as pizotifen. It seems that to prevents migraine you need to block the effect of 5-HT, whereas to treat a migraine you need to have more of it.

5-HT agonists are one of the most recent developments in the treatment of migraine. Sumatriptan has recently been introduced and it seems to be highly effective in the treatment of the established attack. As with many of the other antimigraine drugs, it is important to give it as early in the attack as possible, and injecting it makes sure that it gets into the bloodstream quickly. There is an ingenious plastic device called an auto-injector, which allows you to give your own injection safely and simply, without the need for professional help.

Sumatriptan is also available in tablet form for those in whom vomiting or poor absorption is not a problem. The efficacy is similar, but the onset of action is slightly slower. The only drawback to Sumatriptan is that it is expensive to make.

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