YOHIMBINE 325 



Tablets are sold under the name of vetol for use in veterinary {practice. The 

 stronger tablets contain Gm. .1, or gr. 1% of yohimbine hydrochloride, are colored 

 red and are suitable for the larger animals. The weaker tablets are gray and 

 contain Gm. 0.01, or gr. 1/6 of yohimbine and are suitable for sheep and swine, or 

 divided, for dogs. Treatment should be begun with the smaller doses thrice daily 

 and gradually increased to the larger if no effect is observed from tlie smaller 

 doses. The drug is given with food or drinlcing water, or in tablet form. 



Action. — External. — Yohimbine, in 1 to 2 per cent, solution, has a 

 decided local anesthetic action similar to that of cocaine on the nerve 

 trunks and terminations. Unlike cocaine it does not contract vessels 

 (dilates them) nor cause mydriasis in the eye. It also resembles cocaine 

 in its toxic action on the central nervous system. 



Action. — Internal. — Circulation. — Yohimbine occupies rather a 

 unique position in medicine. Its peculiar therapeutic action consists in 

 stimulation of the sexual organs. Cantharides, used for this purpose, is 

 a powerful irritant to the urinary tract which is not the case with yohim- 

 bine. 



Strychnine, phosphorus, and alcohol stimulate the spinal sexual cen- 

 tres but are uncertain aphrodisiacs. Yohimbine has a specific action in 

 causing local dilatation of the vessels of the testicles, ovaries, penis and 

 vulva so that swelling and congestion of these parts occur. 



The testicles of rabbits, under its influence, become many times their 

 natural size and the external genitals of the larger female animals may 

 be seen to become swollen. Moreover, the lumbar spinal centres con- 

 cerned with erection and the sexual act are directly excited by the drug. 

 The sexual reflexes are made more acute for this reason and because of 

 the increased irritability of the external genitals. 



In the male frequent and prolonged erections appear and sexual 

 excitement is marked in both males and females following its ingestion. 



The author has noted ovarian pain in women taking the drug which 

 may be attributed to swelling of the ovaries. The vascular dilatation is 

 due to direct action of yohimbine on the vessel walls. The cutaneous 

 vessels also dilate, the ears become warmer and redder and the combs in 

 fowl "become more brilliant. Vascular dilatation of the internal organs is 

 said to occur also, with marked lowering of blood pressure. 



The heart is not affected by ordinary doses. 



Nervous System. — Large doses stimulate the central nervous system 

 so that mental excitement and exhilaration (in man), and restlessness 

 ensue. 



Respiration. — Even medicinal doses stimulate the respiratory centre 

 and the movements become deeper and more rapid. 



Mammary Gland. — The action on this gland is similar to that on 

 other parts of the sexual apparatus and congestion and increased milk 

 secretion are observed. 



Toxicology. — Large doses induce restlessness and excitement, rapid 

 pulse and respiration, with fall in blood pressure. Toxic amounts cause 

 convulsions and paresis, diarrhea, salivation, dyspnea and heart weakness. 

 One-half a grain is said to have proved fatal to a dog. 



Uses. — Yohimbine is indicated in functional impotency in the male 



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