6 4 



Scientific Proceedings (103). 



Biologically tested, the cat unit of these solutions was found to be 

 0.107 mg. per kg., their optical rotation — 0.97 0 . After autoclav- 

 ing for 20 minutes at 15 pounds pressure, no alteration in either 

 optical activity or potency was observed in the acid or neutral 

 solutions. The alkaline mixture, however, now had an optical 

 rotation of — 0.93 0 and a cat unit value of 0.152. In short, when 

 strophanthin is autoclaved in alkaline solution (pH 8.6) the 

 molecule is partially decomposed, with resultant alteration in its 

 ability to rotate polarized light and significant reduction in 

 biologic activity. 



For bedside use it is convenient to employ crystalline strophan- 

 thin in dilute concentration, usually 0.01 per cent. Such a 

 solution autoclaved in a soft glass ampule, which, on heating, 

 gives off enough alkali to alter the reaction of its contents to 

 pH 9.0, becomes biologically practically inert, more than four 

 times the calculated lethal dose having no appreciable effect on 

 the cat's heart. The contents of a hard glass ampule, with no 

 significant alteration in pH after sterilization, retain full potency. 



To insure stability of reaction, it is advisable, therefore, to put 

 up solutions of crystalline strophanthin in hard glass (Pyrex) 

 ampules. In order to avoid even slight changes toward the 

 alkaline side, the drug has been prepared for clinical use in Af/50 

 standard phosphate solution, at pH 7.0. The buffer action of this 

 mixture can compensate, with a wide margin of safety, for the 

 amount of alkali yielded, on autoclaving, by the softest variety 

 of glass ampule. 



