[539] Flückiger’s Reactions, 1893.
§ 489. Pharmaceutical Preparations.—The only preparations officinal in this country are a spirituous extract (Extractum physostigmatis), used principally for external application, the dose of which is not more than 18·1 mgrms. (·18 grain), and gelatine discs for the purpose of the ophthalmic surgeon, each disc weighing about 1⁄50th grain, and containing 1⁄1000 gr. of the alkaloid.
§ 490. Effects on Animals.—A large number of experiments have been made upon animals with physostigmine, most of them with the impure alkaloid, which is a mixture of calabarine and physostigmine. Now, the action of calabarine seems to be the opposite to that of physostigmine—that is, it causes tetanus. Hence, these experiments are not of much value, unless the different proportions of the alkaloids were known. Harnack and Witkowsky[540] made, however, some researches with pure physostigmine, of which the following are the main results:—The smallest fatal dose for rabbits is 3 mgrms. per kilo.; cats about the same; while dogs take from 4 to 5 mgrms. per kilo. Frogs, under the influence of the alkaloid, lie paralysed without the power of spontaneous movement, and the sensibility is diminished; later, the breathing ceases, and the reflex irritability becomes extinguished. The activity of the heart is through ·5 mgrm. slowed, but at the same time strengthened.
[540] Arch. f. Pathol. u. Pharm., 1876, Bd. v.
The warm-blooded animals experimented upon show rapid paralysis of the respiratory centre, but the animal by artificial respiration can be saved. Fibrillar muscular twitching of all the muscles of the body are observed. Death follows in all cases from paralysis of the respiration. Experiments (first by Bexold, then by Fraser and Bartholow, and lastly by Schroff) have amply shown that atropine is, to a certain extent, an antidote for physostigmine poisoning. Fraser also maintains an antagonism between strychnine and physostigmine, and Bennet that chloral hydrate is antagonistic to physostigmine.
Effects on Man.—The bean has long been used by the superstitious tribes of the West Coast of Africa as an ordeal, and is so implicitly believed in that the innocent, when accused of theft, will swallow it, in the full conviction that their innocency will protect them, and that they will vomit up the bean and live. In this way, no doubt, life has often been sacrificed. Christison experimented upon himself with the bean, and nearly lost his life. He took 12 grains, and was then seized with giddiness and a general feeling of torpor. Being alarmed at the symptoms, he took an emetic, which acted. He was giddy, faint, and seemed to have lost all muscular power; the heart and pulse were extremely feeble, and beat irregularly. He afterwards fell into a sleep, and the next day he was quite well.
In August 1864 forty-six children were poisoned at Liverpool by eating some of the beans, which had been thrown on a rubbish heap, being part of the cargo of a ship from the West Coast of Africa. A boy, aged six, ate six beans, and died. In April of the same year, two children, aged six and three years, chewed and ate the broken fragments of one bean; the usual symptoms of gastric irritation and muscular weakness followed, but both recovered. Physostigmine contracts the iris to a point; the action is quite local, and is confined to the eye to which it is applied. When administered internally, according to some, it has no effect on the eyes, but according to others, it has a weak effect in contracting the pupil. In any case, the difference of opinion shows that the effect, when internally administered, is not one of a marked character.