The influence of light on the toxicity of quinidin and quinin sulphates

Abstract

It is well known that solutions of quinin and quinidin sulphates 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 paramœcia in sunlight than in the dark. The present author began his studies on frogs. An aqueous solution 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 solution 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. Exactly 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.