Valor

VALOR (Latin), value — a name denoting a conventionally adopted numerical expression of the pharmacodynamic activity of medicinal preparations, determined by biological methods. Valor is established in those cases where, by means of chemical analysis, it is impossible to draw conclusions about the pharmacological activity of the preparation, which is why it becomes necessary to resort to the help of animal experiments. Mostly, valor is expressed in so-called 'units of action' (E. D.). By a unit of action is understood the minimal dose causing a certain pharmacological effect within a certain period of time on a given living object (frog, mouse, dog, individual surviving organs, etc.). By valor, therefore, is understood a certain pharmacological effect corresponding to a certain weight or volumetric quantity of substance in the medicinal preparation. Sometimes valor represents an abstract expression, being the result of a calculation according to a certain empirically established formula [see, for example, the article on the physiological evaluation of ergot in F (VII)]. The definition of valor (proper valorization) acquires the character of biological standardization if to it is joined the subsequent bringing of the preparation to a known standard strength. In 1926, the Hygienic Commission of the League of Nations made an attempt to unify heterogeneous methods of evaluating certain preparations by introducing 'international E. D.' — According to F (VII), valor is officially established for Fol. Digit., H. Adon. vern., Sem. Stroph., Sec. cornut., a series of preparations from them, for adrenaline and pituitrin. The evaluation of preparations by means of determining their valor received especially wide distribution in organotherapy and for derivatives of plant raw material, the active principles of which belong to the group of digitalis glycosides.