(From expectoro, to discharge from the breast). Expectorants, bechita, and bechica. Medicines suited to promote the excretion or rejection of mucus from the bronchial glands. Some expectorants operate by attenuating the mucus; others stimulate the excretories to promote the discharge. We employ expectorants when the mucus is too thin and acrid, when too viscid, or when the excretories are not sufficiently irritable to propel their contents. The former scarcely, perhaps, deserve the title; for they are principally mucilaginous substances; and where the mucus is thin and acrid, inflammation generally exists, not confined to the bronchial glands, but extending to the epiglottis and throat. Mucilages then sheath the inflamed organs, and relief, like the disease, is communicated to the parts below. For this purpose the gums, the mucilaginous seeds, liquorice, honey, extract of malt, starch, sugar, isinglass, glue, etc. are employed. Sometimes they are slightly acid, as the dried fruits of warmer climates, the hips, jelly of currants, sorrel, vinegar softened with the more sweet fruits, as raspberries and sloes. The latter are chiefly employed where there is also a relaxation of the throat and parts adjacent. Oils differently prepared are equally useful, and the coltsfoot, the butterbur, and the groundivy, supposed to possess a slight stimulus, are perhaps chiefly useful as mucilaginous. Independent of inflammation, the mucus is sometimes too thin and acrid, from too great irritability of the vessels of the bronchial glands, and we then employ opiates; the siliquosae, as mustard, horse radish, and different species of erysimum; the allia-ceae; elecampane, and orris-root, the seneka, and col-chicum. When the expectoration is too viscid, or the vessels not sufficiently irritable to assist the excretion, expectorants, strictly so called, are useful. These are the more stimulating medicines just mentioned; to which may be added all the variety of fetid gums, the turpentines, including the balsams, the tobacco, and the squill. Steams of warm water, impregnated with vinegar, aromatic herbs, ether, oil of wine, and carbonic acid, are adapted to the same purpose; and nauseating medicines, as well as emetics, are powerful expectorants; the antimonials and ipecacuanha, perhaps, when inflammation exists; but the squill, the colchicum, and the seneka, in the other cases. The digitalis seems only to act as an expectorant when it nauseates.
Dr. Cullen has found it difficult to explain the action of expectorants; but we have as much reason to suppose that the stimulus of some medicines may be conveyed to the lungs, as of others to the kidneys, or the extreme vessels. We evidently find them conveyed to these organs by the smell imparted to the breath, and the difficulty of explaining the action of specific stimuli will always recur. On this subject the difficulty is perhaps less than on some others, since the vessels of the lungs alternate so regularly in their discharges with those of the skin, and, unlike all other glands, are occasionally excited by increased temperature alone. Their action alternates also with the mucous glands of the intestines; for we find in the pneumonia a supervening diarrhoea constantly checks the expectoration.