78 MEDULLA 



moved. Lipoidal substances separate out at this stage. To 

 eliminate further these lipoidal substances, the aqueous residue 

 is cautiously shaken with petroleum ether. The aqueous layer 

 is separated and precipitated by adding neutral lead acetate, 

 avoiding any excess of this reagent. The lead precipitate is 

 removed by centrifugalization and the remaining fluid con- 

 centrated in vacuo to about 200 cc. A slight excess of NH 4 OH 

 is added to precipitate the epinephrine. To repurify the crude 

 product thus obtained, it is dissolved in 2\ times its weight of 

 10 per cent H 2 S0 4 and an equal volume of ethyl alcohol is 

 added. After filtering, the epinephrine is again precipitated 

 by NH 4 OH. 204 



The racemic form of epinephrine as obtained synthetically 

 is only half as active as the naturally occurring levo-rotatory 

 form. This is due, as Cushny 143 first showed, to the fact that 

 d-epinephrine is only about one-fifteenth as active, for a given 

 weight of substance, as the naturally occurring levo-form. Due 

 regard of this fact has not always been taken and certain syn- 

 thetic products have been utilized whose pharmacological ac- 

 tion was much inferior to the natural product. 



To determine the activity of a given preparation one must 

 resort to the biological assay described in the next section. 

 The degree of racemization of a chemically pure preparation 

 can be determined more easily by the use of a polarimeter 627 



Epinephrine is usually supplied in commerce as a solution 

 of one part per thousand of the hydrochloride dissolved in 

 physiological salt solution. To stabilize the solution, about 

 \ per cent of chloretone is added. The solution is saturated 

 with carbon dioxide to exclude dissolved oxygen and stored 

 in amber colored containers. In faintly acid solution, the drug 

 is stable for a long period. However, in using such prepara- 

 tions, one must consider the possible pharmacological effects 

 of the free acid and the chloretone. Failure to do so has 

 caused some of the discrepancies recorded in the literature. 637 

 For refined work, obviously, a fresh solution of the crystalline 

 base should be used. 



