A new physiologically approached in vitro test for quick evaluation of the hemolytic activity of surfactants.

New physiologically approached in vitro assays are presented which allow rather quick and uncomplicated determinations of the hemolytic activity of surfactants, intended mainly to solubilize poorly soluble drugs in parenteral dosage forms. The extent and the rates of the hemoglobin release from erythrocytes during the incubation of blood with increasing additions of surfactants is thought to be a very suitable and realistic estimation of the membrane damaging side effects of amphiphilic substances. In this study the extent of free hemoglobin released into the plasma is determined by a spectrophotometric method, as well as by an enzymatic determination measuring the lactate dehydrogenase (LDH) activity. LDH is released in a similar way from damaged erythrocytes. The results of these two methods are compared. They correspond satisfactorily.