318 VEGETABLE DRUGS 



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lyze the motor nerve terminations. The local application of cocaine 

 , causes pallor and shrinking of the mucous membrane. The local anes- 

 thesia and vascular constriction last from 15 to 60 minutes. If solutions 

 stronger than 5 % are used there may be some destructive action on proto- 

 plasm and cells, as some local necrosis if injected under the skin, or 

 ulceration of the cornea, if dropped in the eye. Thus strong solutions 

 used for surgery are more prone to be followed by inflammation but such 

 are not required for production of local anesthesia. 



Action Internal. — Digestive Tract. — Cocaine exerts a local anesthetic 

 action upon the gastric mucous membrane, and in this way lessens the 

 appetite and sometimes stops vomiting. Intestinal peristalsis is increased 

 by moderate doses, but is decreased and destroyed by the paralytic action 

 of large doses of cocaine. 



Nervous System. — The general action of cocaine on the nervous sys- 

 tem may be summed up in descending stimulation followed by depression, 

 beginning with the cerebrum and affecting in order the cerebellum, medul- 

 la and spinal cord. Thus mental exhilaration and stimulation of the vital 

 medullary and heat-producing centres (in poisoning) occur. Full doses 

 of cocaine stimulate the psychical functions of the brain and cause intoxi- 

 cation, which is followed, in poisoning, by stupor and convulsions. The 

 convulsions are mainly of cerebral origin, but may be due in part to irri- 

 tation of the spinal reflex centres. These latter centres are first stimu- 

 lated by toxic doses, but depression and paralysis of the spinal cord 

 follows ; the sensory before the motor tract. The sensory nerves are 

 paralyzed and the motor nerves depressed by toxic doses. The voluntary 

 muscles, and probably motor nerve endings, are stimulated by medicinal 

 doses of cocaine, and the alkaloid relieves fatigue and, experimentally, 

 more than doubles the response to stimuli in wornout muscles. Volun- 

 tary muscles are paralyzed by the local application of large quantities of 

 cocaine. Cocaine is essentially a protoplasmic poison when applied even 

 in dilute solution, directly to animal or vegetable cells, including epithelial 

 cells, leukocytes, spermatozoa, muscle and nerves, and all motion or action 

 of these instantly ceases. 



Circulation. — The action of cocaine upon the heart and vessels is not 

 very marked, except in poisoning. The alkaloid is, however, a slight 

 cardiac stimulant in moderate doses, increasing the pulse rate and ten- 

 sion. The action upon the heart is caused, probably, by stimulation 

 of the accelerator center and cardiac muscle. There is a brief initial 

 stimulation of the cardio-inhibitory 'centre which is overcome by the 

 muscular and accelerator effect. Vascular tension is increased because of 

 stimulation of the medullary vasomotor centres, smooth muscle of the 

 vessel walls, and because of the increased action of the heart. On the 

 other hand, both small and large doses may diminish the pulse rate. 

 Toxic doses depress and paralyze the heart muscle and vaso-constrictor 

 centres, and rarely therapeutic doses, used in local anesthesia, may cause 

 sudden collapse through some inexplicable action. 



Respiration. — Cocaine is a respiratory stimulant in medicinal doses, 

 but a paralyzant in toxic amounts. The respiratory centre is first stimu- 



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