The General Use of Histamine Antagonists

most satisfactory and which disorders can be improved by their administration. Recently the equipotent doses of the commonly available preparations have been determined (Bain, Broadbent and Warin, 1949, and Bain, 1949). In this work weals have been induced in the skin of man by intradermal injections of histamine. The size of the weal is less if the injection is made at a suitable interval after one of the drugs has been taken by mouth. By using a series of subjects and carefully measuring the areas of weals provoked before and after giving different doses of the various agents it has been possible to make an accurate comparison of the effectiveness, weight for weight, of the drugs as histamine antagonists in the skin of man. Table I gives the names of the agents which are at present available on the market in this country and the doses that will give the same degree of antihistaminic effect. These equipotent values refer to the administration of single doses only. It is