Abstract
The classical researches of Ladenburg on the structure of atropine and the synthesis of various tropeins led almost immediately to a wide therapeutic application of homatropine as a mydriatic. Inasmuch as the mydriatic action of atropine is known to be through the parasympathetic nerve-mechanism of the eye, namely, the paralysis of the parasympathetic endings of the oculomotor nerve, it has been generally assumed that the mydriatic action of homatropine or tropin-mandelate was of exactly the same nature. An examination of experimental data on the subject, however, gives no proof to support this assumption. In the present investigation, the author became interested in the pharmacology of homatropine in connection with a study of mandelic acid. This acid is closely related to benzaldehyde and indeed can be readily prepared from the latter by treatment with hydrocyanic acid and water. Inasmuch as the author has already shown that benzaldehyde possesses the antispasmodic or relaxant properties on smooth muscle which are exhibited by benzyl alcohol and certain benzyl esters, it was thought possible that the action of homatropine may be exerted, at least partially, directly on smooth muscle itself. A series of expel iments tended to corroborate his view. In the first place, the action of homatropine on other parasympathetic nerve endings, such as the vagus telminals in the heart, is very much weaker than that of atropine. Whereas a small dose of atropine completely paralyzes the vagus endings in the heart, so that electrical stimulation, even of great intensity, fails to inhibit the heart-beat, it takes about ten times as much homairopine to produce the same effect. In the second place, when such experiments on the vagus are performed it is interesting to note that injections of homatropine are followed by a fall in blood pressure and a vasodilatation which is obvious even to the naked eye, when the intestines are inspected.
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