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When two drugs affect each other, it is a drug–drug interaction (DDI). The risk of a DDI increases with the number of drugs used. [1] A large share of elderly people regularly use five or more medications or supplements, with a significant risk of side-effects from drug–drug interactions. [2] Drug interactions can be of three kinds ...
Receptor theory is the application of receptor models to explain drug behavior. [1] Pharmacological receptor models preceded accurate knowledge of receptors by many years. [ 2 ] John Newport Langley and Paul Ehrlich introduced the concept that receptors can mediate drug action at the beginning of the 20th century.
Easson and Stedman [30] (1933) advanced a drug-receptor interaction model to account for the differential pharmacodynamic activity between enantiomeric pairs. In this model the more active enantiomer (the eutomer) take part in a minimum of three simultaneous intermolecular interactions with the receptor surface (good fit), Figure.
These pharmacophore points may be located on the ligand itself or may be projected points presumed to be located in the receptor. The features need to match different chemical groups with similar properties, in order to identify novel ligands. Ligand-receptor interactions are typically "polar positive", "polar negative" or "hydrophobic".
Topics of pharmacodynamics. Pharmacodynamics (PD) is the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs).The effects can include those manifested within animals (including humans), microorganisms, or combinations of organisms (for example, infection).
Furthermore, a drug effect ceases as a drug-receptor complex dissociates. Ariëns & Stephenson introduced the terms "affinity" & "efficacy" to describe the action of ligands bound to receptors. [15] [16] Affinity: The ability of a drug to combine with a receptor to create a drug-receptor complex.
Agonist vs. antagonist. In pharmacology the term agonist-antagonist or mixed agonist/antagonist is used to refer to a drug which under some conditions behaves as an agonist (a substance that fully activates the receptor that it binds to) while under other conditions, behaves as an antagonist (a substance that binds to a receptor but does not activate and can block the activity of other agonists).
Intrinsic activity (IA) and efficacy refer to the relative ability of a drug-receptor complex to produce a maximum functional response. This must be distinguished from the affinity, which is a measure of the ability of the drug to bind to its molecular target, and the EC 50, which is a measure of the potency of the drug and which is proportional to both efficacy and affinity.