In
pharmacology, Schild regression analysis, named for
Heinz Otto Schild
Heinz Otto Schild (18 May 190615 June 1984), was a pharmacologist now known for the development of the Schild plot.
Life
H.O. Schild was born into a Jewish family in what was Fiume, Austria-Hungary, and is now Rijeka, Croatia. During the rise ...
, 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
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