Experimental Quantification of Drug-Receptor Binding Interactions

6 EXPERIMENTAL QUANTIFICATION OF DRUG-RECEPTOR BINDING INTERACTIONS 

The drug-receptor interaction may be quantified through the use of binding constants, which are derived from in vivo pharmacological experiments or from the in vitro use of labeled ligands. 

As shown above, in the reaction of a drug with a single population of noninteracting sites. 

In the direct plot, equation (2.22) is solved for [DR] and its value substituted into equation (2.23)  

y can then be obtained from a plot of v against [D] if the receptor concentration is constant. This is, of course, the same as the direct plot of enzyme activity shown in every biochemistry textbook. As with all hyperbolic relationships, there are several drawbacks to this technique many data points are needed at the beginning of the curve, at low [D] values, where accuracy is limited. Also, determination of the maximum effect is almost impossible, since we are dealing with an asymptotic curve. 

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