Absorption of Drugs from the Esophagus

Abstract

While studying the effect of acute esophageal obstruction in the dog, 1 it was noted that the production of a closed loop of the esophagus was invariably fatal. Although post mortem evidence indicated that death was due to an aspiration pneumonia or to rupture of the loop with subsequent pleuritis and mediastinitis, the possibility of toxin absorption from the esophageal loop was considered. The following experiments were performed to ascertain the absorptive ability of the esophagus under various conditions.

Dogs were used. Under sodium pentobarbital anesthesia, a closed loop of the esophagus was prepared by ligating the esophagus in the neck and in the thorax just above the diaphragm. The substances to be tested were introduced into the lumen of the esophageal loop and the absorption estimated either by chemical tests of the urine and saliva, or by observation of the characteristic physiological effects.

Five experiments were performed in each group. Potassium iodide (in 10% solution), sodium ferrocyanide (in 10% solution), and sodium nitrite (in 5% solution) were all slowly but definitely absorbed under the conditions of these experiments. Histamine hydrochloride (in doses up to 3 mg. per kilo), strychnine sulphate (in doses up to 5 mg. per kilo), cocaine hydrochloride (in doses up to 15 mg. per kilo), ephedrine hydrochloride (in doses up to 10 mg. per kilo), nicotine (in doses up to 2 mg. per kilo), and epinephrine hydrochloride (in doses up to 10 mg. per kilo) were not sufficiently absorbed to produce characteristic effects. Phenolsulphonphthalein, methylene blue, and antipyrine were not sufficiently absorbed during the course of 2 hours to be detected in the urine. Distention of the esophageal loop with air pressure up to 60 mm. of mercury after introduction of the above drugs which were not normally absorbed, caused various reflex disturbances of respiration and blood pressure, but did not apparently facilitate absorption.