Some remarkable products have lately been obtained from atropine by chemical processes. The first step consisted in the discovery, by Kraut and Lossen, simultaneously, that atropine may be split up into tropine and tropic acid. Subsequently, Prof. Ladenburg succeeded in the synthesis of atropine by a combination of these two secondary products. If the salts of tropine are treated with dilute hydrochloric acid, alkaloids are produced, to which Ladenburg has given the name tropeins. Homatropine is an alkaloid obtained from the amygdalate of tropine. The artificial atropine, prepared as above described, has precisely the same effects as the original alkaloid.

Effects of Homatropine

The preparation of this base now used is the hydrobromate. The physiological action of this new salt has been studied by Ringer and Tweedy, among others. Ringer finds that, like atropine, homatropine paralyzes and tetanizes, but the tetanizing effect, which follows in forty-eight hours or more in the former, occurs at once in the latter. The paralyzing action is not in the nerves or muscles, for they respond to electrical stimulation, but in the cord, which is also the case with atropine. Homatropine, like atropine, increases the action of the heart by paralyzing the intra-cardiac inhibitory apparatus, and it also antagonizes muscarine. In man there is a marked distinction as regards the action of atropine and homatropine on the heart: while the former accelerates the heart considerably, the latter retards the beat from ten to twenty per minute, and also makes the action irregular. Homatropine also antagonizes the action of pilocarpine, but it requires relatively more than of atropine to accomplish this result. Ringer sums up his observations with the remark, "Homatropine, then, appears to possess many of the properties of atropine, but in a weaker degree."

Tweedy remarks that, as regards the action of atropine and homatropine relatively on the eye, the effect of homatropine on the iris and ciliary muscle is really very powerful while it lasts. It widely and fixedly dilates the pupil in from fifteen to twenty minutes, and it acts on the accommodation in an equally rapid manner. Its effects pass off rapidly, and in twenty-four hours the accommodation is restored, although the pupil is yet a little dilated. The application of homatropine solution to the eye is entirely unirritating. For these reasons homatropine becomes a valuable substitute for atropine in ocular therapeutics, but it can not be substituted for atropine in the general diseases in which the latter has been found useful.

Authorities referred to:

Bartholow, Dr. R. Prize Essay of the American Medical Association, 1869. The Physiological Effects and Therapeutical Uses of Atropia and its Salts.

Ibid. Manual of Hypodermatic Medication, fourth edition, 1882.

Bezold und Bloebaum. Untersuchungen aus phys. Laborat. in Würzburg. Quoted by Stillé.

Botkin, Dr. S. Virchow's Archiv, vol. xxiv, p. 85.

Donders. On the Anomalies of Accommodation and Refraction of the Eye, Sydenham Society edition.

Eulenburg, Dr. Albert. Lehrbuch der functionellen Nervenkrankheiten, Berlin, 1871, p. 168.

Fluckiger and Hanbury. Pharmacographia, pp. 407, 411.

Fraser, Dr. Thomas R. An Investigation into some Tetanic Symptoms produced by Atropia in Cold-blooded Animals. From "Transactions of the Royal Society of Edinburgh," vol. xxv.

Note

Other references omitted for lack of space, but they are to be seen in all editions previous to the fourth.