Tannic acid in colon examinations.

Abstract

Tannic acid or gallotannic acid as it is more properly called is an ester of gallic acid which was used for many years in the treatment of burns because of its power to precipitate proteins, until Wells, Humphrey and Coll in 1942 and Barnes and Rossiter in 1943 showed that the toxaemia of many so treated was secondary to centrilobular necrosis of the liver caused by absorbed tannic acid. Following this discovery the treatment of burns with tannic acid was gradually abandoned. In 1946 Hamilton advocated the use of tannic acid as an adjuvant in the barium enema for colonic examination. The effect in the colon is to inhibit the secretion of mucin, stimulate contraction of the colon and promote adhesion of barium to the mucosal surface. Since 1946 the use of tannic acid or compounds containing tannic acid has been very widespread and it has been used in millions of patients throughout the world. Little or no scientifically planned investigations were undertaken to assess the safety of the technique until the reports by McAlister, Anderson, Bloomberg and Margulis in 1963 and later in that year by Lucke, Hodge and Patt, of deaths which were or could be attributed to tannic acid in the barium enemas. The use of tannic acid for preparing patients for colonic investigation or for barium enema examinations themselves was prohibited by the Food and Drug Administration in the U.S.A. and the Ministry of Health in this country drew the attention of all radiologists to these reports. The use of the substance was stopped abruptly by most radiologists.