ON THE TOXICITY OF LOCAL ANESTHETICS 



ONE of the most interesting chapters in pharmacology is the 

 discovery and development of the group of drugs acting as 

 local anaesthetics. Thirty years ago the only method of 

 producing local anaesthesia was by means of the ether spray ; 

 to-day we know of many drugs which act more or less specific- 

 ally on sensory nerves, and some of which are used to produce 

 anaesthesia not only for the minor but also for the major 

 operations of surgery. 



Of this group of specific local anaesthetics cocaine was the 

 first and for some time the only member. Isolated in 1860 

 by Niemann, 1 it was stated by him to produce, on tasting, 

 numbing of the sensibility of the tongue. This effect was cor- 

 roborated by de Marie, 2 Lossen, 3 and Moreno-y-Mays. 4 It was 

 not, however, until 1880 that the local anaesthetic action of 

 cocaine was definitely demonstrated. Then von Anrep 5 

 found that, after injecting a 0*6 per cent, solution of the 

 hydrochloride under the skin of his arm, the part became 

 insensitive to the pricking of a needle, and remained so for 

 nearly half an hour. He further observed that the painting 

 of the tongue with a 1 per cent, solution caused loss of sensi- 

 bility and loss of the sense of taste over the painted area ; 

 and that after injection into a frog the sensory nerves lost 

 their irritability before the motor nerves. He suggested the 



1 Liebig's Annalen, cxiv. p. 213 (1860). 



2 (1862), quoted in Schmiedeberg's Pharmakologie. 



3 Liebig's Annalen, cxxxiii. p. 358 (1865). 



* These de Paris, 1868, quoted by von Anrep ; Schmiedeberg, Pharmakologie ; etc. 

 5 Pfluger'8 Archiv, xxi. p. 38 (1880). 



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