Opium.—This is the dried juice of a species of poppy growing in Asia. It contains several alkaloids, the chief of which are morphin and codein. From morphin are prepared artificially two alkaloids—apomorphin and heroin.
Opium depresses the brain, depresses the respiration, stimulates the heart slightly, lessens the peristaltic movements of the bowel, and diminishes all secretions, except the sweat. It is employed to induce sleep, to relieve pain, to allay cough, to check diarrhea, and to promote perspiration.
Opium-poisoning is marked by three stages: the first stage is short and characterized by mental exhilaration; in the second stage the pupils are greatly contracted (pin-point), the respirations are slow, the pulse is slow and full, and there is deep stupor. In the third stage the patient can no longer be aroused (coma), the respiration becomes shallow and irregular, the pulse becomes rapid and weak, the pupils finally dilate, and the patient dies from failure of the respiration.
Even after small doses of opium many patients suffer from headache and nausea. Children are much more sensitive to its action than adults. Morphin resembles opium in action, but is more powerful, less nauseating, and less constipating. Codein is less powerful as a hypnotic and less depressing than morphin.
The dose of opium is from ½ to 1 grain (0.03-0.65 gm.); of the Extract of Opium (Extractum Opii), ⅛ to ½ grain (0.008-0.03 gm.); of the Tincture of Opium or Laudanum (Tinctura Opii), 10 to 20 minims (0.6-1.2 c.c.); of the Camphorated Tincture of Opium or Paregoric (Tinctura Opii Camphorata), ½ to 4 drams (2-15 c.c.); of Dover’s Powder (Pulvis Ipecacuanhæ et opii), 5 to 10 grains (0.3-0.6 gm.); of morphin and its salts (sulphate, hydrochlorate, etc.), ⅛ to ½ grain (0.008-0.03 gm.), and of codein, ½ to 1 grain (0.03-0.06 gm.).
Heroin is chiefly used to allay cough. The dose is from ¹/₁₂ to ⅛ of a grain (0.005-0.008 gm.).
Apomorphin is employed as an emetic and as an expectorant in bronchitis. The dose as an emetic is from ⅒ to ⅙ of a grain (0.006-0.01 gm.), always hypodermically; the dose as an expectorant is from ¹/₂₀ to ¹/₁₀of a grain (0.003-0.006 gm.), always by the mouth.
Paraldehyd.—This is an oily liquid, having a peculiar unpleasant odor and taste. It is used chiefly as a hypnotic. While comparatively safe and reliable, its disagreeable taste and persistent odor on the breath detract from its usefulness. The dose is from ½ to 1 dram (2-4 c.c.), in some pleasant vehicle.
Phenacetin.—This anilin derivative has properties very similar to those of acetanilid, and is used for the same purposes. Dose, 5 to 10 grains (0.3-0.6 gm.).
Physostigma.—This is the seed of a climbing plant growing in Africa. Its activities depend upon an alkaloid known as eserin or physostigmin. It depresses the spinal cord, stimulates the peristaltic movements of the bowel, and, when applied to the eye, contracts the pupil. It is employed to check certain convulsions (tetanus and strychnin-poisoning), to overcome atonic constipation, and, locally, to contract the pupils.