Atropine and Homatropine. 



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 

 homatropine 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. In the third place, 

 a comparative study of atropine and homatropine on uterine, 

 intestinal and other smooth muscle in vitro showed that the 

 relaxant effect of homatropine was much greater than that of 

 atropine. Furthermore, two other esters of mandelic acid which 

 have been employed therapeutically were also found to exhibit 

 marked antispasmodic effects on smooth muscle. These are anti- 

 pyrin-mandelate, or tussol and eucain-mandelate, or euphthalmin . 

 While antipyrin itself and eucain itself have very little effect on 

 smooth muscle the mandelic acid esters of these substances were 

 found to be markedly antispasmodic or depressant for that tissue. 

 Finally, the author has prepared and studied the simple salts of 

 tropic acid and mandelic acid themselves and found that whereas 

 sodium tropate has little or no effect on the contractions and 

 tonus of smooth muscle, sodium mandelate exhibits a relaxant 

 action and when used in strong solution (5 to 10 per cent.), it was 

 found to produce a mydriasis when instilled into a rabbit's eye. 

 The above data indicate pretty conclusively that the mydri- 

 atic effect of homatropine is not entirely due to a paralysis of the 

 parasympathetic innervation but is probably, at least in part, to 

 be explained by direct action of the drug on the muscle cells 

 themselves. Further work on the subject is in progress. The 

 author is investigating the properties of benzyl mandelate. This 

 investigation is supported, in part, by a fund from the Research 

 Council of the American Pharmaceutical Society. 



