[Geometrical method for assessing the interaction of the antidote and the poison in a model experiment].

A method of construction of isobologram and its approximation is proposed for a quantitative assessment of the relationship between a change in LD50 of one substance (poison) and increasing doses of other (antidote). It is recommended to determine the coefficient of the action of the substances on each other. Its value in cases of antagonism is in the range of from 0 to - infinity and in cases of synergism from 0 to + infinity. A formula for the calculation of the coefficient and a geometrical method for the determination of its value are given. The method assumes the identification of a mean error of the coefficient and its confidence limits.