Schild regression

In pharmacology, Schild regression analysis, named for Heinz Otto Schild, is a tool for studying the effects of agonists and antagonists on the response caused by the receptor or on ligand-receptor binding. In pharmacology, Schild regression analysis, named for Heinz Otto Schild, is a tool for studying the effects of agonists and antagonists on the response caused by the receptor or on ligand-receptor binding. Dose-response curves can be constructed to describe response or ligand-receptor complex formation as a function of the ligand concentration. Antagonists make it harder to form these complexes by inhibiting interactions of the ligand with its receptor. This is seen as a change in the dose response curve: typically a rightward shift or a lowered maximum. A reversible competitive antagonist should cause a rightward shift in the dose response curve, such that the new curve is parallel to the old one and the maximum is unchanged. This is because reversible competitive antagonists are surmountable antagonists. The magnitude of the rightward shift can be quantified with the dose ratio, r. The dose ratio r is the ratio of the dose of agonist required for half maximal response with the antagonist B {displaystyle {ce {B}}} present divided by the agonist required for half maximal response without antagonist ('control'). In other words, the ratio of the EC50s of the inhibited and un-inhibited curves. Thus, r represents both the strength of an antagonist and the concentration of the antagonist that was applied. An equation derived from the Gaddum equation can be used to relate r to [ B ] {displaystyle } , as follows: