Botanical name: 

Source and Composition. The commercial dried leaves of Nicotiana Tabacum, (nat. ord. Solanaceae), a native of tropical America. It contains a powerful liquid alkaloid Nicotine,—together with Malic Acid, alkaline salts, and a peculiar camphor named Nicotianin. Its combustion gives rise to several empyreumatic products, of which Pyridine is the most powerful. Tobacco-smoke contains little or no Nicotine; in that from pipes Pyridine preponderates, in that from cigars Collidin, which is much less active.

Liquid Alkaloids besides Nicotine,—Lupuline, Coniïne, Lobeline, Piperidine, Pyridine, Muscarine, Sparteine, and the alkaloidal compound Trimethylamine.

Preparations. Tabácum (as above) is the only official preparation.

*Infusum Tabáci (ʒj to the pint),—Dose, ℥ss-iij, as enema. Dangerous.
*Vinum Tabáci, (℥j to the pint),—Dose, ♏v-ʒj. Must be used cautiously.
*Oleum Tabaci, an empyreumatic product, obtained by distillation.
*Nicotina, Nicotine,—Dose, ♏1/20-1/10, up to ♏ij in strychnine-poisoning.
*Pyridina, Pyridine, C5H5N,—a colorless liquid alkaloid of powerful odor, evaporating when exposed to air, mixing with water in all proportions, and forming salts like Chinolin. Dose, ʒj-ʒjss, allowed to evaporate in an open dish in a small room, in which the patient is exposed for 20 to 30 minutes thrice daily for the relief of asthma (Seé).

Physiological Action. Tobacco is a very depressant nauseant, an emetic by systemic and irritant action, a sternutatory, diuretic, diaphoretic, cathartic, sedative, antispasmodic, and narcotic. It first stimulates and afterwards paralyzes the motor nerves of involuntary muscles, and the secreting nerves of the glands, also the spinal cord and the vagus; at first stimulating both the vagus-roots and its ends in the heart (slowing the pulse-rate), but afterwards paralyzing the latter (causing high pulse-rate). It produces increased salivary and intestinal secretions, diuresis, tremor, clonic spasms, and a tetanic stage previous to its paresis. It contracts the pupils, slows and depresses the heart, first lowers and then raises the arterial tension, and reduces the body temperature; causes profuse sweating, cold and clammy skin, collapse, and death usually by paralysis of respiration, sometimes by paralysis of the heart. It does not impair the muscular irritability, nor does it act on the cerebrum directly. The empyreumatic products of Tobacco are similar in action but less powerful. Fatal results have followed the inhalation of the vapor.

The continued use of Tobacco by smoking or chewing to excess produces granular inflammation of the fauces and pharynx, atrophy of the retina, dyspepsia, lowered sexual power, sudden faints, nervous depression, cardiac irritability and occasionally angina pectoris. Used by the young it hinders the development of the higher nervous centres, and impairs the nutrition of the body by interfering with the processes of digestion and assimilation.

Nicotine is almost as rapidly fatal as Prussic Acid, death having occurred from a toxic dose in three minutes, with no symptoms except a wild stare and a deep sigh.

Antagonists and Antidotes. Strychnine is the true physiological antagonist to Nicotine (or Tobacco) and vice versa. Alcohol, Ammonia, Ergot, Digitalis, Belladonna, etc., antagonize its action on the circulation. Evacuation of the stomach, Tannin, Iodides, and artificial respiration, are the means resorted to in Tobacco-poisoning.

Therapeutics. Tobacco is now but little used in medicine. The chief indications for it are (1) to relax spasm, (2) locally, to relieve pain. But the danger attending its employment, either internally or externally, has caused its supersedence by other agents of less violent action. It may be employed in—

Habitual Constipation,—the wine is a good remedy, ♏v at bedtime. Smokers rarely suffer from constipation, but frequently experience an immediate laxative result after their morning cigar.
Intestinal Affections, as impaction of the caecum, intussusception, and strangulated hernia,—not over ℥iv of the Infusion as an enema has often been very effective in relaxing spasm, but it is a dangerous expedient.
Asthma,—emphysematous, cardiac and nervous forms, are all benefited by the use of Pyridine (as described above); which has a powerfully sedative action upon the respiratory centre.
Tetanus,—no remedy more effective than minim-doses of the alkaloid every two hours by the stomach, or ♏ij by the rectum; or ℥iv of the Infusion as an enema, repeated for effect; or still better, the Wine, in ten-minim doses, repeated for effect.
Dropsy, especially in the renal form,—Tobacco is an efficient diuretic.
Chordee, etc,—are easily conquered by Tobacco.
Strychnine Poisoning,—Tobacco is an effective antagonist,—gr. ss of Nicotine in ʒij Aquae destil. hypodermically; of this ♏x contain gr. 1/24 The Infusion has also been used successfully, but the alkaloid permits of more precise administration.
Fatigue,—Tobacco, moderately used, aids to support the system, when under excessive exertion, food and rest being deficient.

A Compend of Materia Medica, Therapeutics, and Prescription Writing, 1902, by Sam'l O. L. Potter, M.D., M.R.C.P.L.