BELLADONNA AND ATROPINE 175 



Linimentum Belladonnw. 5 per cent, of camphor in fluid- 

 extract of belladonna. 



Unguentum Belladonnw. 10 per cent, of pilnlar extract, 5 

 per cent, alcohol in hydrous wool fat 30 and benzoinated 

 lard 35. 



Atropine. H. gr. %— ^/i; 0.016—0.03. D. gr. Vwo—Vio. 



Action. The action of Belladonna depends upon that of its 

 alkaloid atropine, so the two will be discussed together. 

 Summary of Action. 



1. Stimulation of the nerve centers. 



2. Depression of the nerve endings. 



1. The nerve centers stimulated are the central and vital medul- 

 lary and only in poisonous doses are these depressed. 



2. The nerve endings depressed are : 



a. Sensory nerve endings. There is a tendency to lessen sensa- 

 tion and pain, but not to produce anesthesia. 



b. Motor nerve endings. In smooth muscles but not in striated 

 or arterial muscle. There is a strong action in these muscles, tend- 

 ing to allay abnormal contraction of the muscles of the viscera, 

 bronchi, stomach, intestines, bile ducts, etc. 



c. Secretory nerve endings. There is a strong action on mucous, 

 digestive and skin secretions. 



4. Ends of oculo-motor nerves in the eye leading to a strong and 

 lasting mydriasis. 



5. Vagus nerve endings, so that the usual inhibitory control is 

 lost. 



Atropine is a selective acting drug because it depresses these 

 nerves, whether applied locally or given internally, while there 

 is no effect upon most protoplasm. 



External and Local Action. If placed upon the unbroken 

 skin, atropine has practically no effect, because it is not absorbed, 

 but if it is mixed with some substance which is absorbed and rubbed 

 into the skin or applied to raw surfaces it is an anodyne or anal- 

 gesic, especially if pain is present, due to depression of the sensory 

 nerves. It alsp depresses the terminations of the motor nerves of 

 frogs, but this action has not been seen in mammals. 



Digestive System. Secretions. The ingestion of therapeutic 

 doses causes a decrease in the secretions of saliva and mucous 

 by depressing the nerve endings in the glands and, consequently 

 the mouth and throat become dry. The intestinal secretions 

 tend to be diminished, although the action is somewhat different 

 upon the different ones. The pancreatic secretion is dependent upon 

 the presence in the blood of a chemic substance, secretin, rather than 

 on nerve impulses, so atropine has little or no effect upon the amount 



