Drug-receptor complexes

Table 3. Equilibrium Dissociation Constants for Drug—Receptor Complexes In Vitro...

Efficacy is a parameter which describes the strength of a single drug-receptor complex in evoking a response from the cell or tissue. The intrinsic efficacy of a drag is a proportionality constant that defines the power of the drug to induce a response. 

The dissociation constant for the drug-receptor complex. It is a measurement for the affinity of a drug to a receptor. The lower the value, the higher the affinity. 

KCff, or the dissociation constant of a diug, refers to the rate at which the drug-receptor complex dissociates into separate diug and receptor units. 

On the analogy of the physicochemical relation, one was led to define a biological Hammett equation which related the equilibrium constant of the drug-receptor complex to the electronic a parameters of the substituents (e.g. chlorine, bromine, methyl, ethyl, hydroxyl, carboxyl, acetyl, etc.) of the drug molecule. Since the equilibrium constant of a drug-receptor complex is reflected by the biological activity, this led to the first extrathermodynamic relationship in QS AR ... 

The above Hansch equations are also generally referred to as linear free energy relationships (LFER) as they are derived from the free energy concept of the drug-receptor complex. They also assume that biological activity is linearly related to the electronic and lipophilic contributions of the various substituents on the parent molecule. 

This equation shows that the most relevant computational information on the drug-receptor complex is encoded both in reactivity (hydrogen bond donor propensity) and in shape descriptors. 

Part IV Tools for Investigation of Drug - Receptor Complexes and for Ligand Screening... 

The response may be local or via a signal transduction process. The rate for the forward reaction of drug binding to receptor is proportional to the concentrations of both the drug and target. Conversely, the rate for the reverse reaction (i.e., dissociation of the drug-receptor complex) is proportional to the concentration of the drug-receptor complex. At equilibrium, both forward and reverse reactions are equal. Mathematically, we have... 

The dissociation and association constants have been combined into a new constant, Ka. The total concentration of receptor [Rt] equals unbound receptor concentration [R] plus drug-receptor complex concentration, [DR] ... 

If the drug effect ( ) is proportional to the concentration of drug-receptor complex ... 

The classical occupation theory of Clark rests on the assumption that drugs interact with independent binding sites and activate them, resulting in a biological response that is proportional to the amount of drug-receptor complex formed. The response ceases when this complex dissociates. Assuming a bimolecular reaction, one can write... 

The rate theory of Paton, as modified by Paton and Rang, rejects the assumption that the response is proportional to the number of occupied receptors, and instead proposes a relationship of response to the rate of drug-receptor complex formation. According... 

Drug -F Receptor Drug-Receptor Complex Altered Function... 

D + R- drug-receptor complex- effector molecule- effect... 

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