8 P-AMINOBENZOIC ACID 



field. Most local anesthetics derived from PABA have the structure 



Ri 



/ 

 -COOXN 



\ 

 R2 



HoN- 



^ /y 



Table I lists some of the more common anesthetics of this type. The 

 specific substituents for the variables in the general formula are indicated. 



TABLE I 

 Common Local Anesthetics Derived from PABA 



The nature of the substituents X, Ri , Ro determines to a large extent the 

 degree of toxicity as well as of anesthetic efficiency of the particular ester. 

 In general, the longer the group X (up to ?i-butyl), the greater is the anes- 



