For some time we have been studying blood prothrombin levels in human beings. It seemed of particular interest to one of us (L. P.) to investigate the effect of certain drugs which are administered prophylactically or therapeutically over long periods on the prothrombin level. Among the most widely used compounds of this type are the antimalarials, and the present paper deals with the effect of quinine on the prothrombin time.
Five normal male subjects ranging in age from 18 to 43 years were chosen. Their nutritional state was satisfactory and they were advised to maintain a well balanced diet. The prothrombin time was normal in all instances. Two to four premedication controls, performed in each case, were in agreement within the range of normal variations. In carrying out the estimations the Page1 method was used. According to this technic viper venom and calcium chloride are added to plasma obtained