Influence of Light on Toxicity. 



397 



196 (1943) 



The influence of light on the toxicity of quinidin and quinin 



sulphates. 



By D. I. MACHT. 



[From the Pharmacological Laboratory of the Johns Hopkins 

 University, Baltimore, Md.l 



It is well known that solutions of quinin and quinidin sul- 

 phates are fluorescent. This fact suggested an inquiry into 

 whether such solutions are as toxic in the dark as when exposed 

 to light. Accordingly the present investigation was undertaken 

 to settle this question. Such an inquiry was deemed to be worth 

 while especially in view of the older observations by H. Tappeiner 

 and O. Raab in 1900, 1 who noted that solutions of the dye acridin 

 were much more toxic for paramcecia in sunlight than in the dark. 

 The present author began his studies on frogs. An aqueous solu- 

 tion of quinidin sulphate was made. Various doses of the same 

 were injected into the anterior lymph sacs of frogs and the effects 

 of the drug were studied by exposing some frogs to light while 

 keeping others in darkness. It was found that the quinidin solu- 

 tion was much more toxic when animals were exposed to sunlight 

 than when they were kept in the dark. Thus for instance in one 

 experiment a dose of quinidin sulphate, 0.5 mgm. per gm. weight, 

 was injected into the anterior lymph sac of a rana clamata. Ex- 

 actly the equivalent dose of quinidin from the same solution was 

 injected into a second frog in the same way. The first frog was 

 exposed to sunlight. It was found to be paralyzed 25 minutes 

 after injection, and the heart was found to have been arrested 

 completely 30 minutes after injection. The second frog was 

 placed in a dark cupboard and was still alive 24 hours after the 

 beginning of the experiment. Similar experiments with varying 

 doses of quinidin were performed many times and a comparison 

 of the data thus obtained clearly indicated that the toxicity of the 

 drug was much greater when the frogs were exposed to sunlight. 

 Insamuch as a difference in temperature may affect to some ex- 

 tent the condition of frogs, especially as regards their central 

 nervous system, control experiments were made to determine 



1 Zeit. f. Biologic 1900, xxxix, 37. 



