Journal (I) xi., xiv., and (2) x.; E. Impey, Report on Malwa Opium (Bombay, 1848) ; Report on Trade of Hankow (1869) ; New Remedies (1876) ; Pharmacographia (1879) ; Journ. Soc. Arts (1882) ; The Friend of China (1883), etc.; Report of Straits Settlements, Federated Malay States, Opium Corn mission, app. xxiii. and xxiv. (1908) ; A. H. Allen, Commercial Organic Analysis, vol. iii. (1924) ; F. Browne, Report on Opium (Hongkong, 1908) ; W. Watt, Dictionary of the Economic Products of India (1892) ; H. Moissan, Comptes Rendus (1892) ; E. Lalande, Archives de medicine navale (189o) ; International Opium Commission, Report of Delegations, vol. ii. (1909) ; P. W. Squire, Companion to British Pharmacopoeia (1908). (E. M. Ho.) Medicine.—Of the opium alkaloids only morphine and codeine are used to any extent in medicine. Thebaine is not so used, but is an important and sometimes very dangerous constituent of the various opium preparations, which are still largely em ployed, despite the complexity and inconstant composition of the drug. Of the other alkaloids narceine is hypnotic, whilst thebaine, papaverine and narcotine have an action which resembles that of strychnine. So complex a drug as opium is necessarily incompatible with a large number of substances. Tannic acid, for instance, precipitates codeine as a tannate, salts of many of the heavy metals form precipitates of meconates and sulphates, whilst the various alkalis, alkaline carbonates and ammonia precipi tate the important alkaloids.
The pharmacology of opium differs from that of morphine (q.v.) in a few particulars. The chief difference is due to the presence in opium of thebaine, which readily affects the more ir ritable spinal cord of very young children. In infants especially opium acts markedly upon the spinal cord, and, just as strychnine is dangerous when given to young children, so opium, because of the strychnine-like alkaloid it contains, should never be adminis tered, under any circumstances or in any dose, to children under one year of age.
When given by the mouth, opium has a somewhat different action from that of morphine. It often relieves hunger, by arrest ing the secretion of gastric juice and the movements of the stomach and bowel, and it frequently upsets digestion from the same cause. Often it relieves vomiting, though in a few persons it may cause vomiting, but in far less degree than apomorphine, which is a powerful emetic. Opium has a more marked diaphoretic action than morphine, and is much less certain as a hypnotic and analgesic.
(See also DRUG ADDICTION and PoisoN).— Under this heading must be considered acute poisoning by opium, and the chronic poisoning seen in those who eat or smoke the drug. Chronic opium poisoning by the taking of laudanum—as in the familiar case of De Quincey—need not be considered here, as the hypodermic injection of morphine has almost entirely sup planted it.
The acute poisoning presents symptoms not easily distinguished from those produced by alcohol, by cerebral haemorrhage and by several other morbid conditions. The differential diagnosis is of the highest importance, but very frequently time alone will fur nish a sufficient criterion. The patient who has swallowed a toxic or lethal dose of laudanum, for instance, usually passes at once into the narcotic state, without any prior excitement. Intense drowsiness yields to sleep and coma which ends in death from failure of the respiration. This last is the cardinal fact in deter mining treatment. The comatose patient has a cold and clammy skin, livid lips and ear-tips—a grave sign—and "pin-point pupils." The heart's action is feeble, the pulse being small, irregular and often abnormally slow. The action on the circulation is largely secondary, however, to the all-important action of opium on the respiratory centre in the medulla oblongata. The centre is directly poisoned by the circulation through it of opium-containing blood, and the patient's breathing becomes progressively slower, shal lower and more irregular until finally it ceases altogether.
In treating acute opium poisoning the first pro ceeding is to empty the stomach. The best emetic is apomorphine, which may be injected subcutaneously in a dose of about one-tenth of a grain. But the gastric wall is often paralysed in opium poison ing, so that no emetic can act. It is therefore better to wash out the stomach, at half-hour intervals, with a solution containing about ten grains of salt to each ounce of water. If apomorphine is obtainable, both of these measures may be employed. Potassium permanganate decomposes morphine by oxidation, the action be ing facilitated by the addition of a small quantity of mineral acid to the solution. The physiological as well as the chemical antidotes must be employed. The chief of these are coffee or caf feine and atropine. A pint of hot strong coffee may be introduced into the rectum, and caffeine in large doses—ten or twenty grains of the carbonate—may be given by the mouth. A twentieth, even a tenth of a grain of atropine sulphate should be injected sub cutaneously, the drug being a direct stimulant of the respiratory centre. Every means must be taken to keep the patient awake. He must be walked about, have smelling salts constantly applied to the nose, or be stimulated by the faradic battery. But the final resort in cases of opium poisoning is artificial respiration, which should be persevered with as long as the heart continues to beat.