PILOCARPUS — PILOCARPINE 207 



body on account of stimulation of their motor nerve endings. Thus 

 we have contraction of the plain muscles of the digestive tract, blad- 

 der, bronchi and ciliary muscle. 



Circulation. The effects of the drug on this system are complex 

 and vary somewhat on the different species of animals. The primary 

 effect of the drug is to stimulate the cardiac terminations of the vagus 

 and slow the heart. This is followed by paralysis of the vagus with 

 rapid pulse from large doses. Later the heart becomes depressed 

 giving a slow, weak pulse, due to weakness of that organ and depres- 

 sion of the vasomotor center, Finally the heart is paralyzed. After 

 toxic doses the arterioles are dilated by depression of the vasomotor 

 center and blood pressure falls. 



Pilocarpine must therefore be regarded as a cardiac depressant, 

 acting both upon the vagus and directly upon the heart, and in exces- 

 sive doses is a vasodilator. Its margin of safety is small and it 

 should not be used in cardiac weakness. 



Respiratory System. The secretions of the bronchi are in- 

 creased ; the bronchi are contracted on account of stimulation of their 

 nerve endings. On account of these actions the breathing in poison- 

 ing may be labored or asthmatic. Horses affected with heaves have 

 dyspnea after moderate doses. On account of these factors, together 

 with a weak circulation, death may take place from edema of the 

 lungs, asphyxia or collapse. 



Temperature. The temperature may be lowered if profuse 

 sweating takes place. This is especially so in febrile conditions. 



Secretions. Besides the secretions mentioned above, pilocarpine 

 increases the secretion of mucus, tears and sweat. In man there is a 

 very profuse secretion of sweat but this is not seen in the lower ani- 

 mals. In the horse the skin may become moist, but the salivary secre- 

 tion is very profuse. It will take place in from 5 to 10 minutes after 

 the hypodermic administration of a therapeutic dose and persists for 

 % to 2 hours. Salivation is accompanied by clamping of the jaws 

 and movements of the tongue. 



Hair. The hair sometimes increases after local application or 

 internal administration of pilocarpine. 



,Eye. Applied locally pilocarpine contracts the pupil by stimula- 

 tion of the endings of the oculomotor nerve in the iris and lessens 

 intraocular pressure. The eye is fixed in accommodation for near 

 objects. 



Therapeutics. 



1. To increase secretions of the gastrointestinal tract, combined' 

 with eserine, as in obstinate constipation or impactions in horses or 



cattle. 



2. Direct antidote to atropine and should be given in doses four 

 times as great as the atropine. 



