Abstract
Based on the theory to characterize the bacteriostatic and bactericidal actions of drugs proposed by Takahashi, further theoretical considerations were attempted on the bactericidality of a drug and its concentration dependence. An index term to show the bactericidality as a function of drug concentration was defined and the concentration dependence was graphically drawn on the basis of inhibitory parameters determined calorimetrically. The result was obtained that if the parameters characterizing the apparent cooperativity in drug actions obtained from the growth rate is different from those obtained from the growth retardation, the bactericidality changes largely depending on the drug concentration. The result was also found to be consistent with the observation for some drugs where the SCI plot defined previously does not show a straight line, but exhibits an upward curvature.
