(Abstracted from a series of papers on the "Progress of Therapeutics", published in the Medical Times and Gazette.)
The Physostigma venenosum, or ordeal bean of Old Calabar, has of late been used medicinally. Its peculiar and powerfully poisonous properties were long ago made known by Drs. Christison and Balfour, but we owe the fuller knowledge we now possess of its powers to the elaborate investigations of Dr. Fraser, of Edinburgh, Dr. Robertson and other observers. The active principles of the bean quickly enter the blood and gradually produce general paralysis, which is due, according to Dr. Fraser, to changes effected in the spinal cord. In an animal poisoned by the bean the reflex functions of the cord are destroyed—"It acts on the spinal cord by destroying its power of conducting impressions." This results "in muscular paralysis, gradually extending to the respiratory apparatus, and producing death by asphyxia; and, in a rapid paralysis of the heart, causing death by syncope. It also causes paralysis of muscular fibre, striped and unstriped." The knowledge obtained by these investigations led to the employment of the bean as a remedy in tetanus, and a considerable number of cases have been treated by it. Dr. Fraser has a high opinion of its value, and has reported twelve cases of tetanus treated by it, of which nine recovered. Many other cases of its administration in this disease have been reported in the various medical journals, English and foreign, and in not a few of these instances the patients have undoubtedly recovered; but the results, on the whole, have scarcely supported Dr. Fraser's estimate of the remedial value of the drug, while in some cases it has been suspected of doing harm rather than good, and of increasing the patient's danger by its paralysing action. (Mr. Holthouse's case, Clinical Society's Transactions, vol. ii.; and Medical Times and Gazette, 1869.) It has been observed, too, that in most of the cases of recovery the disease lasted about a month, just as in cases successfully treated with atropia, hydrate of chloral, and other remedies. The physostigma has been employed in other maladies. It is indisputably a weapon of great power, and must be used with great care and watchfulness; at the same time, in such a disease as tetanus, it must, as Dr. Fraser has insisted, be employed early. The Pharmacopoeia contains two preparations, the powder and an extract; the first may be given by the mouth, in doses of from one to four grains for an adult; the extract, subcutaneously, in doses of one-tenth to one-third of a grain and more, the dosage being regulated by the effects.
The physostigma has also the peculiar properties of causing very rapidly contraction of the iris, and altering the power of accommodation of the lens, and it has been largely used and proved of great value in ophthalmic practice. Its action on the iris was first pointed out by Dr. Fraser, (On the Characters, Actions and Therapeutic Uses of the Ordeal Bean of Calabar." Graduation Thesis. August, 1862. Edinburgh Medical and Surgical Journal, 1863.) and first made use of by Dr. Argyll Robertson. (Edinburgh Medical and Surgical Journal, 1863.) A very interesting communication on the subject, by Mr. J. Soelberg Wells, containing a description by Mr. Bowman of the effects of a solution of the bean on his own eye, was published in the Medical Times and Gazette in 1863. ("On the Effects of the Solution of the Calabar Bean on the Pupil,", etc., Medical Times and Gazette, vol. i, p. 500, 1863.) It may be applied by touching the inside of the eyelid with a solution, one minim of which equals four grains of the bean, or by placing within a minute portion of paper which has been saturated with a strong solution.—Lond. Pharm. Journ., Jan. 21, 1871. (Before you even consider trying a stunt like this, read up on the toxicity of Physostigma in King's American Dispensatory. It can kill you, if you get enough on the conjunctiva.)