noun

definition

An alkaloid extracted from the plant deadly nightshade (Atropa belladonna) and other sources, such as the seeds of the Thorn-apple. Though overdoses would be fatal it is used as a drug in medicine for its paralytic effects (e.g. in surgery to relax muscles, in dentistry to dry the mouth, in ophthalmology to dilate the pupils).

Examples of atropine in a Sentence

The treatment is to empty the stomach by tube or by a non-depressant emetic. The physiological antidotes are atropine and digitalin or strophanthin, which should be injected subcutaneously in maximal doses.

Use hot bottles and stimulants, especially trying to counteract the cardiac depression by atropine, caffeine, strophanthin, &c.

Piperine, conine, atropine, belladonine, cocaine, hyoscyamine and nicotine have been already synthesized; the constitution of several others requires confirmation, while there remain many important alkaloids - quinine, morphine, strychnine, &c. - whose constitution remains unknown.

There is a marked antagonism in nearly all important particulars between the actions of physostigmine and of atropine.

Unfortunately the antagonism between physostigmine and atropine is not perfect, and Sir Thomas Fraser has shown that in such cases there comes a time when, if the action of the two drugs be summated, death results sooner than from either alone.

Thus atropine will save life after three and a half times the fatal dose of physostigmine has been taken, but will hasten the end if four or more times the fatal dose has been ingested.

Of these the more important are atropine (or atropia), hyoscyamine, hyoscine and belladonine; atropine is the most important, occurring as the malate to the extent of about o 4 7% in the leaves, and from o.

Hydrolysis with hydrochloric acid or baryta water gives tropic acid and tropine; on the other hand, by boiling equimolecular quantities of these substances with dilute hydrochloric acid, atropine is reformed.

The official doses of atropine are from to 1+F grain, and the sulphate, which is in general use in medicine, has a similar dose.

So valuable are certain of the properties of atropine that it is often desirable to give doses of one-twentieth or onetenth of a grain; but these will never be ventured upon by the practitioner who is ignorant of the great interval between the minimum toxic and the minimum lethal dose.

When rubbed into the skin with such substances as alcohol or glycerine, which are absorbed, atropine is carried through the epidermis with them, and in this manner - or when simply applied to a raw surface - it paralyses the terminals of the pain-conducting sensory nerves.

Certain nerve fibres from the sympathetic nervous system, which can also cause the secretion of a (specially viscous) saliva, are entirely unaffected by atropine.

There is much uncertainty as to the influence of atropine on the secretions of the stomach, intestines, liver, pancreas and kidneys, and it is not possible to make any definite statement, save that in all probability the activities of the nerves innervating the glandcells in these organs are reduced, though they are certainly not arrested, as in the other cases.

Given internally, atropine does not exert any appreciable sedative action upon the nerves of pain.

The action of atropine on the motor nerves is equally important.

But moderate doses of atropine markedly paralyse the terminals of the nerves that go to involuntary muscles, whether the action of those nerves be motor or inhibitory.

These are paralysed by atropine, and intestinal peristalsis is consequently made more active, the muscles being released from nervous control.

The motor nerves of the arteries, of the bladder and rectal sphincters, and also of the bronchi, are paralysed by atropine, but the nervous arrangements of those organs are highly complex and until they are further unravelled by physiologists, pharmacology will be unable to give much information which might be of great value in the employment of atropine.

But whilst the characteristic action of atropine is to dilate the blood-vessels, its first action is to stimulate the vaso-motor centre - thereby causing temporary contraction of the vessels - and to increase the rapidity of the heart's action, so that the blood-pressure rapidly rises.

Though transient, this action is so certain, marked and rapid, as to make the subcutaneous injection of atropine invaluable in certain conditions.

The respiratory centre is similarly stimulated, so that atropine must be regarded as a temporary but efficient respiratory and cardiac stimulant.

Toxic doses of atropine - and therefore of belladonna - raise the temperature several degrees.

In small therapeutic and in small toxic doses atropine stimulates the motor apparatus of the spinal cord, just as it stimulates the centres in the medulla oblongata.

No less important than any of the above is the action of atropine on the cerebrum.

Thereafter a more or less sleepy state supervenes, but it is not the case that atropine ever causes genuine coma.

It is to be noted that children, who are particularly susceptible to the influence of certain of the other potent alkaloids, such as morphine and strychnine, will take relatively large doses of atropine without ill-effect.

The action of atropine on the eye is of high theoretical and practical importance.

The result of its instillation into the eye - and the same occurs when the atropine has been absorbed elsewhere - is rapidly to cause wide dilatation of the pupil.

The action of atropine in dilating the pupil is also aided by a stimulation of the fibres from the sympathetic nervous system, which innervate the remaining muscle of the iris - the dilator pupillae.

The sight of many an eye has been destroyed by the use of atropine - in ignorance of this action on the intra-ocular tension - in cases of incipient glaucoma.

The use of atropine is absolutely contra-indicated in any case where the intra-ocular tension already is, or threatens to become, unduly high.

This warning applies notably to those - usually women - who are accustomed indiscriminately to use belladonna or atropine in order to give greater brilliancy to their eyes.

The fourth ocular result of administering atropine is the production of a slight but definite degree of local anaesthesia of the eyeball.

It follows from the above that a patient who is definitely under the influence of atropine will display rapid pulse, dilated pupils, a dry skin and a sense of discomfort, due to dryness of the mouth and throat.

Generally speaking, it may be laid down that atropine is more likely than iodine to relieve a pain of quite superficial origin; and conversely.

Atropine is universally and constantly used in ophthalmic practice in order to dilate the pupil for examination of the retina by the ophthalmoscope, or in cases where the inflamed iris threatens to form adhesions to neighbouring parts.

The drug is often replaced in ophthalmology by homatropine - an alkaloid prepared from tropine - which acts similarly to atropine but has the advantage of allowing the ocular changes to pass away in a much shorter time.

The anhidrotic action of atropine is largely employed in controlling the night-sweats so characteristic of pulmonary tuberculosis, small doses of the solution of the sulphate being given at night.

The uses of atropine in cardiac affections are still obscure and dubious.

Professor Schafer recommended the use of atropine prior to the administration of a general anaesthetic, in cases where the action of the vagus nerve upon the heart is to be dreaded; and there is little doubt of the value of this precaution, which has no attendant disadvantages, in all such cases.

In cases of whooping-cough or any other condition in which there is spasmodic action of the muscular fibre in the bronchia definition which includes nearly every form of asthma and many cases of bronchitis - atropine is an almost invaluable drug.

In treating an actual and present attack of asthma, it is advisable to give the standardized tincture of belladonna - unless expense is no consideration, in which case atropine may itself be used - in doses of twenty minims every quarter of an hour as long as no evil effects appear.

The excellent toleration of atropine displayed by children must be remembered, and if its use is "pushed" a cure may almost always be expected.

The symptoms of poisoning by belladonna or atropine are dealt with above.

Hypodermic tabloids of morphine sulphate either alone or combined with atropine are much in use.

Irritation is lessened by lotions containing substances that will diminish irritability of the nerve-endings and skin, such as carbolic acid, hydrocyanic acid, morphine or opium, cocaine, belladonna or atropine.

The chief of these are coffee or caffeine and atropine.

A twentieth, even a tenth of a grain of atropine sulphate should be injected subcutaneously, the drug being a direct stimulant of the respiratory centre.

Henbane yields a poisonous alkaloid, hyoscyamine, which is stated to have properties almost identical with those of atropine, from which it differs in being more soluble in water.

Recent researches on arsenic and atropine, however, point to the leucocytes as playing an important part in the production of tolerance, as these gradually become capable of ingesting large amounts of the foreign substances, and thus render them more or less harmless to the tissues, until they are gradually excreted from the body.

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