In cases where the cause of the attacks can be ascertained, the cause is to be removed. Thus in gouty patients the free use of water as a beverage, and the administration of iodide and bromide of potassium or of salicylate of sodium may be useful. In renal asthma the diet must be chiefly farinaceous and fatty, meat and beef-tea being sparingly given, so as to avoid the accumulation of waste products in the system, and caffeine (pp. 433, 434) may be given to aid their elimination. The asthma of dyspepsia, and also that of constipation, may possibly be due partly to the presence of abnormal digestive products in the blood, as well as to irritation of the mucous membrane of the stomach or intestine. In dyspeptic asthma pepsin has proved very useful; emetics are sometimes of service, probably by removing irritating substances (p. 255), and ipecacuanha may possibly have some special action of its own on the mucous membrane, in addition to its emetic action. Constipation is to be treated by laxatives (p. 388) and cholagogues (p. 404), and worms by vermifuges (p. 408). Polypi in the nose and enlarged tonsils are to be removed, and for congestion of the mucous membrane of the nose or throat, carbolic acid lotion may be used (p. 257).

The medicine most usually employed to prevent recurrence of the attack is lobelia inflata. The exact mode of action of this drug is not known, but the general symptoms produced by it so closely resemble those of tobacco that it is often known as Indian tobacco, and possibly its action on the bronchial tubes may be somewhat the same as those of nicotine. During the attacks of spasmodic asthma more relief is usually afforded by the inhalation of smoke of various kinds than by any other means. The smoke of tobacco, of the leaves of various species of datura, of paper impregnated with potassium nitrate, or with a mixture of potassium nitrate and chlorate; of pastiles and of various powders, which probably are principally composed of powdered daturaleaves, mixed with powdered nitre, and perhaps, also, with ipecacuanha, all prove useful. The action of all these smokes is probably the same as that of nicotine, for Vohl and Eulenbergl have shown that the active principles in tobacco-smoke really are not nicotine, but are the products of the dry distillation of tobacco-leaves, consisting chiefly of pyridine, collidine, and allied substances. The same products, but in different proportions, are obtained by the dry distillation of other organic bodies. The proportion in which the different bases are present depends both on the nature of the substances subjected to dry distillation, and on the amount of oxygen present during the process. When much oxygen is present, bodies of higher atomic weight and less volatile than those lower in the series are formed, much collidine being produced when tobacco is smoked as a cigar, while pyridine is the chief product when it is smoked in a pipe. It is probable that the admixture of nitre with paper or with powdered leaves acts beneficially by producing a different mixture of organic bases than would be produced by burning the paper or the leaves alone, and that we must look to bodies allied to collidine for the relief of asthma.

1 Arch. Pharm. (2), 1873, vol. cxlvii. 130-166.