This section is from the book "A Practitioner's Handbook Of Materia Medica And Therapeutics", by Thos. S. Blair. Also available from Amazon: A Practitioner's handbook of Materia Medica and Therapeutics.
Pilocarpus, Jaborandi. This is a drug presenting a whole train of difficulties to the honest pharmaceutic chemist. There are twenty-one varieties of Pilocarpus leaves in trade, and of these species only two conform to official requirements. The other leaves are used. Comment upon the cheap fluidextracts is unnecessary. An honestly made assayed fluidextract is prepared by several houses, and is thoroughly representative. The ec. tr. is made entirely from pilocarpus microphyllus, the eclectics claiming it to be much superior to the other official leaf, pilocarpus jaborandi. As a matter of fact, the chemistry of pilocarpus is so involved that it is a difficult matter to pass upon this question or to assign any therapeutic place to the several alkaloids derived from it, with the exception of the official pilocarpine salts. The average dose of the U. S. P. assayed fluidextract is given as 30 I,, which I consider too high. However, it must be said that a trace of jaborine exists in most fluidextracts, and official standards do not require its removal. This alkaloid is antagonistic to pilocarpine, and this renders the large dose necessary. Some chemists claim that pilocarpine is partially converted into jaborine by heating. If this is true, a fluidextract should be made absolutely without the aid of heat. Whatever views may be entertained as to the eclectic idea of rejecting pilocarpus jaborandi, the fact remains that their eclectic tincture or fluidextracts of pilocarpus microphyllus should be given in less dose than the other preparations. The maximum single dose of the ec. tr. is I 3, and the eclectics consider this dangerous. The full dose is 20 to 30 I,. My own idea is that it contains very little jaborine, and hence the small dose. The U. S. P. requirement of 0.5% total alkaloids is very unsatisfactory as an assay standard in view of the involved alkaloidal chemistrv.
In large doses some practicians employ I 3 of the eclectic tincture or 2 of the fluidextract at one single dose to establish crisis in severe febrile diseases where a fatal outcome is threatening. It is claimed that under such circumstances it equalizes the circulation and relieves internal congestion. In some cases a hypodermic of 1/2 gr. of pilocarpine hydrochlorate is preferable. The maximum single dose of this salt is 2-3 gr. This large dose should never be given in ordinary ailments nor in threatened. heart failure, but in semi-moribund cases it does not react upon the skin to any great extent. In proportion to age, nearly as large doses are now given in diphtheria with impending suffocation from accumulation of dry membrane, but in very young infants it does not do very well. In general, it may be said that when we want the action of large doses of pilocarpine, it is best to employ the alkaloidal salts, since no jaborine is to be contended with. The average dose is 1-5 gr., but 1/4 to 1-3 gr. may be given in robust patients with sthenic disease. The physician should take atropine and brandy along, and remain with the patient for an hour after administering pilocarpine. These doses are indicated in some acute febrile and inflammatory conditions with rigor and a bounding pulse, and sometimes as a sedative to the heart in other conditions. It is much employed in dropsy when the heart is not weakened. It appears to be of distinct value in markedly sthenic puerperal eclampsia and uremic convulsions. If in parturition the skin is hot and dry, the os very rigid, the pains severe but ineffective, and the pulse bounding, a full dose of pilocarpus gives excellent results. Large doses are sometimes given in croup.
Pilocarpus antidotes atropine poisoning, and, to some extent, the venom of snakes, rabid animals, and the ptomaines of decomposed fish and meats, but it is not employed to the exclusion of other indicated remedies. In moderate doses (f.e., 15 I.; ec. tr., 6 to 8 I; pilocarpine, 1/8 gr.) it is of value in inflammatory rheumatism, in inflammation of the lungs and pleura with exudation, stridulous laryngitis (dose reduced to suit age), laryngeal diphtheria, bronchial asthma, acute orchitis and ovaritis, sthenic erysipelas, lumbago, pleurodynia, serous iritis and rheumatic iritis, simple glaucoma, retinal hemorrhage, chorio-retinitis, interstitial keratitis, and in effusion into the labyrinth of the middle ear.
In small doses its action upon the skin is sufficient to aid in exanthematous fevers (ec. tr., )Ii to 2 111.). Quite small doses are of value in sthenic fevers, especially where there is dry, bronchial irritation with imperfect secretion (ec. tr., 2 to 4 I.). Where there is relaxation of the cutaneous vessels, due to tuberculosis and other debilitating diseases and causing excessive sweating, the little 1-100 gr. granules of pilocarpine give relief. They are also useful in mumps, the salivation of pregnancy, scanty urination, edema from Bright's disease, laryngeal and pulmonic edema. These little granules can be frequently repeated. As an active galactagogue, small but larger doses than these are required. Used externally, pilocarpine is directed in I to 2'70 aqueous solution as a collyrium to contract the pupil. The alkaloid, instead of its salts, is used. Fluidextract of pilocarpus is a constituent of some hair tonics. Atropine in 1-100 gr. dose antagonizes or antidotes 1-6 gr. pilocarpine. Homceopathic physicians employ the third dilution of pilocarpus in exophthalmic goitre with asserted benefit.