Source and Composition. The leaflets of Pilocarpus Selloanus and of Pilocarpus Jaborandi, Brazilian plants of the nat. ord. Rutaceae, containing two alkaloids,—Pilocarpine and Jaborine, which though isomeric are antagonistic in action;-also a volatile oil and probably a peculiar acid.
- Extractum Pilocarpi Fluidum,—Dose, ♏v-ʒj, but generally inert.
- Pilocarpinae Hydrochloras, gr. 1/10-½. Hypodermically, gr. ⅙ may be given.
Physiological Action. Pilocarpus is a paralyzer of the vaso-motor system, and a stimulant of the peripheral terminations of nerves supplying glands and involuntary muscular fibre, subsequently paralyzing the latter. It is therefore a powerful diaphoretic and sialagogue, a cardiac depressant by stimulation of the vagus ends,—also myotic, emetic, and under some circumstances abortifacient. Its taste is hot and pungent. It causes prompt and profuse perspiration (℥ ix-xv, in quantity) and salivation (℥x-xxvij), after a preliminary flushing of the skin. The nasal, bronchial and lachrymal secretions are much increased; sometimes watery diarrhoea occurs; the action of the heart, at first increased, is afterwards lowered, the arterial tension is reduced, and the temperature falls from 1° to 4°. Drowsiness, pallor, chilliness and debility succeed, and last several hours; the pupil is contracted and accommodation impaired. The elimination of urea is greatly increased, but not the quantity of urine. The respiratory power is lowered, and apnoea may occur, from increase of the bronchial mucus.
Pilocarpus is rapidly diffused, and is eliminated by the skin and the salivary glands. Its effects pass off usually in from three to six hours. Children are less affected than adults, by proportionate doses. It causes contractions of the bladder, uterus and spleen, in the latter case whether the organ is enlarged or of normal size.
Antagonists. Atropine is a complete physiological antagonist in dose of gr. 1/100 for gr. ⅙ of Pilocarpine. The antagonism extends over their whole range of action, and is the most complete known to physiological experimentation. Conversely, the same is true, but Jaborine acts similarly to Atropine, and is antagonistic to Pilocarpine. Strychnine, though from a member of the same family, antagonizes the effects on the heart and respiration, and Morphine controls the nausea and vomiting. Artificial respiration, to maintain life until elimination occurs, and repeated evacuation of the bladder, are important measures in poisoning by this drug.
- Therapeutics. Pilocarpus is well used in—
- Ptyalism—a minute dose of Pilocarpine (gr. 1/30) acting on the same gland will antagonize the morbid action and relieve the excessive secretion (Bartholow, Piffard). Perspiration of profuse character is checked by gr. 1/20 of Pilocarpine given thrice daily (Ringer).
- Diphtheria and Erysipelas,—are diseases in which it proves efficient, but in which its depressant action on the heart must be remembered.
- Amblyopia from alcohol and tobacco, keratitis, choroiditis, chronic iritis, detached retina, and many other eye affections,—Pilocarpus is very beneficial.
- Pleuritis, Meningitis and other inflammations of serous membranes,—it is remarkably efficient in removing exudations.
- Dropsy is its chief field of action, especially renal dropsy; but it is contraindicated when the heart is weak from any cause.
- Diabetes Insipidus,—it reduces the quantity of urine remarkably, relieving the kidneys by throwing the work on the skin.
- Agalactia,—Pilocarpus promptly stimulates the secretion of milk.
- Uraemia and Puerperal Eclampsia of renal origin,—it has been used with marked success. Parotitis is promptly relieved by it.
- Bright's Disease,—Pilocarpine has been used with great advantage in both the acute and chronic forms, but is so depressing that it must be employed with extreme caution in this disorder.
A Compend of Materia Medica, Therapeutics, and Prescription Writing, 1902, by Sam'l O. L. Potter, M.D., M.R.C.P.L.