502 



SCIENCE 



[N. S. Vol. LI. No. 1325 



coneentration. This is the first of the 

 aromatic side-chain alcohols to equal cocaine 

 as a surface anesthetic. 



The following diagram (adapted from Soll- 

 mann) illustrates the comparative eiEciency 

 of phenolic side-chain alcohols and the com- 

 monly used surface anesthetics: 



Minimum 



Anesthetic 

 Percentage Relative Efflclency for Surlace Anesthesia 



0.5 Coeaine , holocaine, benz oyl carbinol 



0.75 a-(phenethylol 



1.0 Beta-Eucaine, rose oil 



1.25 Benzyl alcohol 



2 Tropaeocame, alypin, quinine-urea 



1 Apothesline 



8 isiovocaine 



10 Amtipyrine 



The intracutaneous method of testing local 

 anesthetics was introduced by Hoffmann and 

 Kochmann (1914) and consists in the produc- 

 tion of wheals resembling mosquito bites, by 

 driving the anesthetic substance in between 

 the layers of the epidermis, under pressure, 

 with the hypodermic syringe. The subject of 

 the experiment, who is, of course, prevented 

 from watching the procedures, is required to 

 give a signal every time he perceives the 

 touch of a straw tipped with absorbent cotton. 

 None of our phenolic alcohols are found 

 irritating by this method and all destroy sen- 

 sation in a concentration of about 1/40 of 1 

 per cent., as low a strength as has proved 

 sufficient for any known anesthetic substance. 



This is illustrated by the following diagram 

 (also adapted from Sollmarm) : 



Minimum 



Anesthetic Relative Efflclency for Intracutaneous 



Percentage Anesthesia 



1/40 Benzoyl carbinol, rose oil, a-phene- 



' " thylol 



1/30-1/32 Benzyl alcohol, cocaine, no^'o- 



caine, tropacocame, alypin 



1/16 Beta-eucaine 



1/8 Quinin-urea 



1/4 Apothesine, antipyrine, K^SOj 



Dr. Arthur D. Hirschfelder,'' of Minne- 



13 Hirschfelder, A. D., A. Lundholm, H. Norr- 

 gaard, American Chemical Society, Division of 

 Btiochemistry, September 4, 1919. 



apolis, and his collaborators, have recently an- 

 nounced the results of experiments with 

 similar side-chain aromatic alcohols. A num- 

 ber of these are based upon the salicylic acid 

 radical. From Hirschfelder's results it is ob- 

 vious that saligenin in 2 per cent solution is 

 likely to prove a very valuable anesthetic. 

 In his hands this has given a 28—45 minute 

 human subcutaneous anesthesia and has com- 

 pletely anesthetized the mucous membranes 

 of the eye. 



Several benzyl alcohol homologues, there- 

 fore, which are more stable than benzyl alco- 

 hol itself, better surface anesthetics than pro- 

 caine, and at least five times less toxic, and 

 which further are presumably very unlikeiy 

 to become habit-forming drugs, are now re- 

 ceiving practical trials. 



The two above described tests, surface and 

 intracutaneous, represent the most important 

 of the procedures employed by the siirgeons. 

 Clinically, there are five main varieties of 

 local anesthesia, namely, (1) surface, (2) 

 terminal, (3) regional, (4) spinal, (5) venous. 



1. To anesthetize mucous membranes such 

 as the linings of the eye, nose, and throat, the 

 solution requires only to be painted upon the 

 siirface. 



2. To anesthetize the nerve ends in the skin, 

 however, it is necessary that the drug be 

 injected into the skin by means of the hypo- 

 dermic needle. This is owing to the fortunate 

 circumstance that the living la.yers of the 

 epidermis are quite impermeable to most 

 solutions with which they may come in con- 

 tact. Obviously where deper incisions are to 

 be made, subcutaneous injections must follow. 

 Schleich^'' modified the method of terminal 

 anesthesia very acceptably by showing that 

 if hypotonic solutions be injected under 

 pressure to the point at which the tissues 

 become rigid, the anesthetic may be reduced 

 in concentration. Tliis is in accord with 

 findings that either hypotonic or hypertonic 

 solutions of salts tend of themselves to pro- 

 duce local anesthesia, apparently owing to the 

 fact that in swelling or shrinking respectively, 



i« Schleich, 0. L., "Schmerzlose Operationen, " 

 Berlin, 1906. 



