This section is from the book "A Text-Book Of Pharmacology, Therapeutics And Materia Medica", by T. Lauder Brunton. Also available from Amazon: A text-book of pharmacology, therapeutics and materia medica.
Papaverine. Codeine. Narcotine. Thebaine.
the appearance of the first edition of this book by the following annotation in the Lancet, which seems to show that emetic substances (? alkaloids) are excreted in the saliva of opium-eaters : - An envelope received from a person who habitually took large quantities of morphine hypodermically was reclosed by the person who opened it, by licking the adhesive surface, with the result of making him violently sick. - Lancet, May 23, 1885, p. 959.
The codeine group contains also hydrocotarnine, laudanosine, and cryptopine; but at present we know too little about them to assign a place in the group to them with certainty. The same may be said of codethyline. The codeine group becomes closely allied by its last members with the strychnine group.
By the addition of alcohol-radicals to morphine, substances to which the name of codeines has been given are produced. In some of these, such as codethyline, C17H18NO2(OC2H5), obtained from morphine by the introduction of ethyl, the narcotic action is diminished, whilst, according to Von Schroeder, the convulsive action is increased, in proportion to the number of atoms of hydrogen substituted by alcohol-radicals. If such be the case it is remarkable that by the addition of alcohol-radicals to codeine or thebaine, their tetanising action should be altered into a paralysing action, methyl-thebaine producing paralysis like methyl-strychnine.1
In the alkaloids produced from morphine by oxidation (oxydimorphine and oxymorphine) the narcotic action is diminished, without the convulsant action being increased. Narceine has no apparent physiological action.2
Apomorphine has no narcotic action, but is an emetic acting on the vomiting centre in the medulla. In large doses it does not produce vomiting, but causes peculiar manege movements.
Morphine is said to be less constipating, less diaphoretic, and less nauseating than opium. Others affirm that opium is less nauseating. It is also said that opium quickens the pulse and raises the temperature at first, and then depresses both, while morphine depresses them both from the first.
The activity of morphine appears to depend on the presence of hydroxyl (HO) in it. When this is replaced by SO4 its activity is greatly diminished.3
Therapeutics. - General Uses. - The general uses of opium in disease are (1) to lessen pain; (2) to produce sleep; (3) to lessen irritation in various organs.
Local Uses. - Opium is a local sedative, and is applied to the skin and irritable surfaces to relieve pain, thus: Fomentations or liniments containing it are used for inflamed joints, myalgia, lumbago, pleurisy, peritonitis, herpes zoster, etc.
Morphine dissolved in glycerine and spread on lint is used to allay pain in cancer; and, applied either by the endermic or hypodermic method, is useful in neuralgia. In many cases, however, the injection of pure water will relieve the pain, and hence part of the relief is probably due to the local irritation caused by the injection.
1 Crum-Brown and Fraser, Trans. Boy. Soc. of Edinburgh, vol. xxv.
2 Von Schroeder, Archiv f. exper. Path, und Pharm., vol. xvii. p. 96.
3 Stolnikow, Ztschr. f. Physiol. Chemie, viii. p. 236.
Opium lessens pain in conjunctivitis, earache, and toothache. In conjunctivitis it may be used in the form of liquid extract dropped into the eye; and in toothache applied to the cavity of the tooth as laudanum on a pledget of cotton wool. In the latter malady it is well to add a little sodium bicarbonate, to neutralise the acid secretions in the mouth.
Opium, used in the form of ointment of galls and opium, or of opium or morphine suppositories, relieves pain in the rectum caused either by ulcers, fissure, or haemorrhoids.
Morphine subcutaneously injected has been used to produce local anaesthesia, as in evulsion of the toe-nail.
Digestive System. - Opium often relieves salivation when due to reflex irritation in the mouth; if this fails, belladonna may succeed (p. 361).
It relieves the pain and vomiting due to irritability of the stomach, as in cancer and ulcer of the stomach, but if they are due to simple neuralgia of the stomach, small doses of arsenic are preferable.
In biliary colic opium or morphine is given either by the stomach or hypodermically. It may be used either with, or instead of, the inhalation of chloroform (pp. 208 and 209).
In diarrhoea opium is often useful when ordinary astringents fail.
In dysentery it is generally combined with ipecacuanha.
In cholera opium is frequently given, but during the cold stage absorption is so slow that it has very little action. In these cases patients have been known to die from opium-poisoning, as soon as partial recovery had taken place and absorption was re-established.
In peritonitis it is used both internally and externally. It should be given freely in doses of 1-2 gr. every four hours or oftener, and fomentations to the abdomen should be used externally. The action of the opium in this disease is twofold, and possibly threefold:- (i.) It stops the peristalsis of the bowel. (ii.) It relieves pain. (iii.) It has possibly an action on the bloodvessels, lessening congestion in the manner already discussed (p. 855).
Very small doses (1 or even 1/2 drop of tinctura opii in syrup or peppermint water) relieve certain forms of constipation, e.g. that caused reflexly by ovarian irritation. The opium probably acts on some reflex centre in the lumbar portion of the cord, and the minute dose probably just turns the reflex impulse from the inhibitory to the motor fibres of the splanchnic (p. 385). If these small doses are insufficient, the opium may be gradually increased until it is clear that it is increasing instead of lessening the constipation.
Respiratory Tract. - Opium will cut short catarrhal conditions of the respiratory tract, and 10 grains of Dover's powder at night are very useful when a 'cold' is coming on. It is also used in phthisis to cut short an acute exacerbation due to taking cold (p. 331).