See serotonin agonists; serotonin antagonists.
5HT1 agonist (triptan) any one of a class of drugs that stimulate *serotonin (5-hydroxytryptamine) receptors and are effective in the relief of *migraine headaches by causing constriction of cerebral blood vessels. The group includes almotriptan, naratriptan, *sumatriptan, and zolmitriptan.
It usually begins at puberty – although young children can be affected – and tends to stop in middle age: in women, for example, attacks often cease after MENOPAUSE. It frequently disappears during pregnancy. The disorder tends to run in families. In susceptible individuals, attacks may be provoked by a wide variety of causes including: anxiety, emotion, depression, shock, and excitement; physical and mental fatigue; prolonged focusing on computer, television or cinema screens; noise, especially loud and high-pitched sounds; certain foods – such as chocolate, cheese, citrus fruits, pastry; alcohol; prolonged lack of food; irregular meals; menstruation and the pre-menstrual period.
Anything that can provoke a headache in the ordinary individual can probably precipitate an attack in a migrainous subject. It seems as if there is an inherited predispostion that triggers a mechanism whereby in the migrainous subject, the headache and the associated sickness persist for hours, a whole day or even longer.
The precise cause is not known, but the generally accepted view is that in susceptible individuals, one or other of these causes produces spasm or constriction of the blood vessels of the brain. This in turn is followed by dilatation of these blood vessels which also become more permeable and so allow ?uid to pass out into the surrounding tissues. This combination of dilatation and outpouring of ?uid is held to be responsible for the headache.
Two types of migraine have been recognised: classical and common. The former is relatively rare and the headache is preceded by a slowly extending area of blindness in one or both eyes, usually accompanied by intermittent ‘lights’. The phenomenon lasts for up to 30 minutes and is followed by a bad, often unilateral headache with nausea, sometimes vomiting and sensitivity to light. Occasionally, passing neurological symptoms such as weakness in a limb may accompany the attack. The common variety has similar but less severe symptoms. It consists of an intense headache, usually situated over one or other eye. The headache is usually preceded by a feeling of sickness and disturbance of sight. In 15–20 per cent of cases this disturbance of sight takes the form of bright lights: the so-called AURA of migraine. The majority of attacks are accompanied by vomiting. The duration of the headache varies, but in the more severe cases the victim is usually con?ned to bed for 24 hours.
Treatment consists, in the ?rst place, of trying to avoid any precipitating factor. Patients must ?nd out which drug, or drugs, give them most relief, and they must always carry these about with them wherever they go. This is because it is a not uncommon experience to be aware of an attack coming on and to ?nd that there is a critical quarter of an hour or so during which the tablets are e?ective. If not taken within this period, they may be ine?ective and the unfortunate victim ?nds him or herself prostrate with headache and vomiting. In addition, sufferers should immediately lie down; at this stage a few hours’ rest may prevent the development of a full attack.
When an attack is fully developed, rest in bed in a quiet, darkened room is essential; any loud noise or bright light intensi?es the headache or sickness. The less food that is taken during an attack the better, provided that the individual drinks as much ?uid as he or she wants. Group therapy, in which groups of around ten migrainous subjects learn how to relax, is often of help in more severe cases, whilst in others the injection of a local anaesthetic into tender spots in the scalp reduces the number of attacks. Drug treatment can be e?ective and those a?icted by migraine may ?nd a particular drug or combination of drugs more suitable than others. ANALGESICS such as PARACETAMOL, aspirin and CODEINE phosphate sometimes help. A combination of buclizine hydrochloride and analgesics, taken when the visual aura occurs, prevents or diminishes the severity of an attack in some people. A commonly used remedy for the condition is ergotamine tartrate, which causes the dilated blood vessels to contract, but this must only be taken under medical supervision. In many cases METOCLOPRAMIDE (an antiemetic), followed ten minutes later by three tablets of either aspirin or paracetamol, is e?ective if taken early in an attack. In milder attacks, aspirin, with or without codeine and paracetamol, may be of value. SUMATRIPTAN (5-hydroxytryptamine [5HT1] AGONIST – also known as a SEROTONIN agonist) is of value for acute attacks. It is used orally or by subcutaneous injection, but should not be used for patients with ischaemic heart disease. Naratriptan is another 5HT1 agonist that is an e?ective treatment for acute attacks; others are almotriptan, rizariptan and zolmitriptan. Some patients ?nd beta blockers such as propranolol a valuable prophylactic.
People with migraine and their relatives can obtain help and guidance from the Migraine Action Association.... migraine
They work on the same receptors in the brain as 5 hydroxytryptamine (5HT), a neurotransmitter and vasodilator.
Common serotonin agonists include naratriptan and sumatriptan.
These drugs can cause chest pain, particularly in people with heart disease.
They should be used with caution in those at increased risk of coronary artery disease.
Other side effects include flushing, tingling, and nausea.... serotonin agonists
Causes Vomiting is brought about by stimulation of this nervous centre, and in most cases this is e?ected through sensations derived from the stomach itself. Thus, of the drugs which cause vomiting, some act only after being absorbed into the blood and carried to the brain, although most are irritants to the mucous membrane of the stomach (see EMETICS); various diseases of the stomach, such as cancer, ulcer and food poisoning act in a similar way. Stimulation – not only of the nerves of the stomach, but also of those supplying other abdominal organs – produces vomiting; thus in obstruction of the bowels, peritonitis, gall-stone colic, renal colic, and even in some women during pregnancy, vomiting is a prominent symptom.
Severe emotional shock may cause vomiting, as may acute anxiety and unpleasant experiences such as seeing an accident, suffering severe pain or travel sickness.
Direct disturbance of the brain itself is a cause: for example, a blow on the head, a cerebral tumour, a cerebral abscess, meningitis. Nausea and vomiting are common symptoms that may arise from local disease of the gastrointestinal tract, but they are also associated with systemic illness – for example, DIABETES MELLITUS or kidney failure (see KIDNEYS, DISEASES OF) – and also with disturbances of labyrinthine function, such as motion sickness and acute labyrinthitis.
Treatment The cause of the vomiting must be sought and treatment directed towards this. Symptomatic treatment for vomiting can be dangerous since accurate diagnosis of the cause may be hindered. If antinauseant drug treatment is indicated, the choice of drug depends on the cause of the vomiting.
Granisetron and ondansetron are 5hydroxytryptamine (5HT3) antagonists valuable in the treatment of nausea and vomiting induced by cytotoxic CHEMOTHERAPY or RADIOTHERAPY and prevention and treatment of post-operative nausea and vomiting. Prochlorperazine is valuable in the treatment of severe nausea, vomiting, VERTIGO and disorders of the LABYRINTH of the EAR, although extrapyramidal symptoms may occur, particularly in children, elderly and debilitated patients.
Vomiting may occur after surgical operations and this is due to the combined effects of analgesics, anaesthetic agents and the psychological stress of operation. Various drugs can be used to prevent or stop post-operative vomiting.
Nausea and vomiting are common symptoms in pregnancy. Drugs are best avoided in this situation as they may damage the developing FETUS. Simple measures, such as the taking of food before getting up in the morning and reassurance, are often all that is necessary.... vomiting
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