1911 Encyclopædia Britannica/Jaborandi
|←Jablonski, Daniel Ernst||1911 Encyclopædia Britannica, Volume 15
|See also Pilocarpus on Wikipedia; and our 1911 Encyclopædia Britannica disclaimer.|
JABORANDI, a name given in a generic manner in Brazil and South America generally to a number of different plants, all of which possess more or less marked sialogogue and sudorific properties. In the year 1875 a drug was introduced under the above name to the notice of medical men in France by Dr Coutinho of Pernambuco, its botanical source being then unknown. Pilocarpus pennatifolius, a member of the natural order Rutaceae, the plant from which it is obtained, is a slightly branched shrub about 10 ft. high, growing in Paraguay and the eastern provinces of Brazil. The leaves, which are placed alternately on the stem, are often 1½ ft. long, and consist of from two to five pairs of opposite leaflets, the terminal one having a longer pedicel than the others. The leaflets are oval, lanceolate, entire and obtuse, with the apex often slightly indented, from 3 to 4 in. long and 1 to 1½ in. broad in the middle. When held up to the light they may be observed to have scattered all over them numerous pellucid dots or receptacles of secretion immersed in the substance of the leaf. The leaves in size and texture bear some resemblance to those of the cherry-laurel (Prunus laurocerasus), but are less polished on the upper surface. The flowers, which are produced in spring and early summer, are borne on a raceme, 6 or 8 in. long, and the fruit consists of five carpels, of which not more than two or three usually arrive at maturity. The leaves are the part of the plant usually imported, although occasionally the stems and roots are attached to them. The active principle for which the name pilocarpine, suggested by Holmes, was ultimately adopted, was discovered almost simultaneously by Hardy in France and Gerrard in England, but was first obtained in a pure state by Petit of Paris. It is a liquid alkaloid, slightly soluble in water, and very soluble in alcohol, ether and chloroform. It strongly rotates the plane of polarization to the right, and forms crystalline salts of which the nitrate is that chiefly used in medicine. The nitrate and phosphate are insoluble in ether, chloroform and benzol, while the hydrochlorate and hydrobromate dissolve both in these menstrua and in water and alcohol; the sulphate and acetate being deliquescent are not employed medicinally. The formula of the alkaloid is C11H16N2O2.
Jaborandi — a, leaf (reduced); b, leaflet (natural size); c, flower; d, fruit (natural size).
Certain other alkaloids are present in the leaves. They have been named jaborine, jaboridine and pilocarpidine. The first of these is the most important and constant. It is possibly derived from pilocarpine, and has the formula C22H32N4O4. Jaborine resembles atropine pharmacologically, and is therefore antagonistic to pilocarpine. The various preparations of jaborandi leaves are therefore undesirable for therapeutic purposes, and only the nitrate of pilocarpine itself should be used. This is a white crystalline powder, soluble in the ratio of about one part in ten of cold water. The dose is 1/20-½ grain by the mouth, and up to one-third of a grain hypodermically, in which fashion it is usually given.
The action of this powerful alkaloid closely resembles that of physostigmine, but whereas the latter is specially active in influencing the heart, the eye and the spinal cord, pilocarpine exerts its greatest power on the secretions. It has no external action. When taken by the mouth the drug is rapidly absorbed and stimulates the secretions of the entire alimentary tract, though not of the liver. The action on the salivary glands is the most marked and the best understood. The great flow of saliva is due to an action of the drug, after absorption, on the terminations of the chorda tympani, sympathetic and other nerves of salivary secretion. The gland cells themselves are unaffected. The nerves are so violently excited that direct stimulation of them by electricity adds nothing to the rate of salivary flow. The action is antagonized by atropine, whjch paralyses the nerve terminals. About 1/100th of a grain of atropine antagonizes half a grain of pilocarpine. The circulation is depressed by the drug, the pulse being slowed and the blood pressure falling. The cardiac action is due to stimulation of the vagus, but the dilatation of the blood-vessels does not appear to be due to a specific action upon them. The drug does not kill by its action on the heart. Its dangerous action is upon the bronchial secretion, which is greatly increased. Pilocarpine is not only the most powerful sialogogue but also the most powerful diaphoretic known. One dose may cause the flow of nearly a pint of sweat in an hour. The action is due, as in the case of the salivation, to stimulation of the terminals of the sudorific nerves. According to K. Binz there is also in both cases an action on the medullary centres for these secretions. Just as the saliva is a true secretion containing a high proportion of ptyalin and salts, and is not a mere transudation of water, so the perspiration is found to contain a high ratio of urea and chlorides. The great diaphoresis and the depression of the circulation usually cause a fall in temperature of about 2° F. The drug is excreted unchanged in the urine. It is a mild diuretic. When given internally or applied locally to the eye it powerfully stimulates the terminals of the oculomotor nerves in the iris and ciliary muscle, causing exteme contraction of the pupil and spasm of accommodation. The tension of the eyeball is at first raised but afterwards lowered.
The chief therapeutic use of the drug is as a diaphoretic in chronic Bright's disease. It is also used to aid the growth of the hair — in which it is sometimes successful; in cases of inordinate thirst, when one-tenth of a grain with a little bismuth held in the mouth may be of much value; in cases of lead and mercury poisoning, where it aids the elimination of the poison in the secretions; as a galactagogue; and in cases of atropine poisoning (though here it is of doubtful value).