It is frequently found to be directly proportional to the concentration of radioligand added. It is determined experimentally by measuring the residual binding of radioligand in the presence of a saturating concentration of a drug which, ideally, is chemically dissimilar to the radioligand but is selective for the same receptor. NSB See non-specific binding . The proportion of receptors to which a drug is bound. See also Hill equation for a related equation.
Operational model See mathematical model .
The negative logarithm of the molar concentration. Partial agonist An agonist which, no matter how high a concentration is applied, is unable to produce maximal activation of the receptors. In a preparation with a low receptor reserve , it is therefore unable to produce as great a maximal response as a full agonist . See also efficacy and intrinsic efficacy . It is usually calculated by Schild analysis by extrapolating the line on a Schild plot to the x-axis.