Origin

Lobelia in flata, or Indian tobacco, is a small annual or biennial, indigenous plant, growing abundantly in most parts of the United States. Though the seeds are the strongest portion, the whole herb is officinal, and is directed in our Pharmacopoeia, under the name of lobelia. it should be gathered in August and September, when the fruit is most abundant. Sometimes it is kept simply dried, sometimes in powder, and not unfrequently comminuted and compressed in the form of small oblong cakes.

Properties

Lobelia is of a greenish colour in powder, of a feeble, somewhat irritating odour, and of a taste which is slight at first, but soon becomes acrid and nauseating, and spreads with a strong and peculiar acrimony through the fauces, not a little resembling that of tobacco. The herb imparts its virtues to water and alcohol. They are injuriously affected by a boiling heat. They probably reside chiefly, if not exclusively, in a peculiar organic alkaloid, called lobelina, which exists in the herb in combination with an acid There is also a very small proportion of volatile oil, upon which its odour depends, but which probably possesses little medical efficiency.

Lobelina was first procured in a pure state by Professor Procter, of Philadelphia, who obtained it from the seeds by the following process. A tincture, prepared by treating the seeds with alcohol acidulated with acetic acid, is evaporated, and the resulting extract mixed with water and magnesia, by which the alkaloid is separated from its saline combination. The mixture is agitated with ether, which dissolves the lobelina, and yields it in an impure state by evaporation. it is purified by dissolving it in water, adding sulphuric acid in slight excess, boiling with animal charcoal, then separating it as before by magnesia, filtering, agitating the liquid with ether until wholly deprived of acrimony, and allowing the ethereal solution to evaporate.

Thus obtained, lobelina is a yellowish liquid, lighter than water, of a somewhat aromatic odour, and a very acrid and durable taste. it is soluble in water, but more so in alcohol and ether, the latter of which separates it from its aqueous solution. it has an alkaline reaction, and forms salts with the acids, most of which are soluble and crystallizable. With tannic acid, however, it forms an insoluble compound. At a boiling heat it is decomposed. A drop of it, given to a cat, rendered the animal prostrate and nearly motionless, with dilated pupils, for an hour; and the effects had not quite disappeared at the end of fifteen hours. it neither vomited nor purged.

Effects on the System

Lobelia is locally irritant, and, in its general influence, sedative to the nervous and circulating systems. in certain doses it operates as a nauseating emetic, and sometimes as a cathartic, and, in smaller doses, is expectorant and diaphoretic.

When chewed in small quantities it often produces, along with the peculiar acrimony in the mouth, fauces, and oesophagus, giddiness, headache, and general tremors, and at length, if continued, nausea and vomiting. in a larger dose, it acts promptly as an emetic, with distressing and continued nausea, copious sweating, feeble pulse, pale skin, and great general relaxation. Sometimes, as from digitalis, the pulse becomes intermittent. The Rev. Dr. Cutler states that it produced in himself a prickly sensation throughout the system, and a smarting sensation in micturition.

Poisonous Effects

Lobelia, in over-doses, is capable of acting as a violent poison, and, being a favourite remedy with a certain class of uneducated empirics, has been in their hands the cause of numerous deaths, both in this country and Great Britain. At an inquest held in England, in November, 1853, on the occasion of a death from lobelia, Dr. Letheby, Professor of Chemistry in the London Hospital, stated that thirteen cases of poisoning had occurred from that drug, within the three or four preceding years, and that, in six of them, a coroner's jury had brought in a verdict of manslaughter. {Loud. Med. Times and Gazette, May, 1854, p. 491.) When lobelia vomits, it is, like tobacco, less apt to produce fatal effects; and, as this happens in most instances when large doses are taken, the ignorant practitioner, thinking that he has proved the innocence of the medicine by his experience with it, gives it freely and without hesitation in all cases. But in some individuals it fails to vomit, even in very large and repeated doses; and it is in these cases that death most commonly results. it is wonderful with what recklessness, according to published reports, the poison has been sometimes thrown in, dose after dose, in the cases of these insusceptible individuals, in the expectation that it would at length operate in the desired manner.

The effects of a poisonous dose of lobelia are usually a peculiar sensation of burning and acrimony in the fauces and oesophagus, intense epigastric distress with or without vomiting and purging, general anxiety, a feeble pulse, faintness, muscular tremors and relaxation, profuse sweats, coldness of the surface, vertigo, and, finally, extreme prostration, delirium, stupor, sometimes convulsions, and death. From one poisonous dose, the fatal result may take place in five or six hours; but frequently the effect is produced by a succession of doses, repeated hour after hour, or day after day, so that it is impossible to determine the precise duration of the poisonous process. Nor is the quantity well determined, which will ordinarily prove fatal. in fact, the susceptibility to its effects is so variable, that no precise statement can be made on this point. Much, too, depends upon the occurrence or non-occurrence of vomiting. Dr. Letheby found in the stomach of a woman who had been poisoned with it, 110 grains; in the case of a man, a tablespoonful of the seeds; and in a child three years old, fifteen grains of the seeds in the bowels. He stated, in reference to the first instance just mentioned, that he had known much less than that quantity produce death, and thought that one-third of the amount found in the stomach would have been sufficient to kill the patient. (Lond. Med. Times and Gazette, as above; also March, 1853, p. 270.) it was the seeds that appear to have been given in these cases; and, as they are probably at least twice as strong as the herb generally, allowance must be made in estimating the poisonous dose of the latter. in most cases recorded, the quantities mentioned are quite indefinite, though often stated as large. From all that I have seen, I should infer that a drachm of the dried herb would be a dangerous dose, which ought not to be hazarded at once; though, if it should vomit, the patient might experience no serious inconvenience; and much larger quantities have, no doubt, often been given with impunity. inflammation of the stomach and bowels has been noticed after death. But the probability is that the poison destroys life through its influence on the encephalic centres, especially that of respiration in the medulla oblongata; for, in animals poisoned with it, the heart continues to act after breathing has ceased. This fact was noticed in the experiments of Mr. Curtis and Dr. Pearson upon hedgehogs and cats. They state also that the lungs and the venous system generally were congested, as uniformly happens in death from asphyxia, and that the blood was fluid. (ibid., Aug. 1850, p. 285.) The treatment of poisoning by lobelia is the same as in the case of tobacco.