THE PHYSIOLOGICAL DISPOSITION OF LIDOCAINE AND ITS COMPARISON IN SOME RESPECTS WITH PROCAINE

The methyl orange method was applied for the determination of lidocaine in biological materials. Lidocaine was found to be well absorbed when injected intramuscularly in the rat and the addition of epinephrine greatly slowed its absorption. One hour after lidocaine was given intramuscularly to a rat, the highest concentration was found in the kidney. Lung, spleen, fat, heart and brain had appreciable levels whereas very low levels were present in the liver and blood. Lidocaine disappeared very rapidly from the blood when it was given intravenously. Only a small fraction of the administered drug could be recovered from the excreta. Liver was found to be the chief organ for the metabolism of lidocaine. The difference between the actions of lidocaine and procaine can be explained in part by the differences of their physiological disposition.