Pharmacodynamics DR Interactions and Pharmacodynamics Pharmacodynamics Describes the actions of drugs on the body and the influence of drug concentration on the magnitude of the response ID: 1014065
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1. Drug-Receptor Interactions and Pharmacodynamics
2. D-R Interact.ions and PharmacodynamicsPharmacodynamics Describes the actions of drugs on the body and the influence of drug concentration on the magnitude of the responseSignal Transduction Ligands Second Messenger Drug-Receptor Complex Drug + Receptor Drug-Receptor Complex Biologic Effect
3. Receptor?????
4. ReceptorAny biologic molecule to which a drug binds and produces a measurable response. enzymes, nucleic acids, and structural proteins can act as receptors for drugs or endogenous agonistsMost of receptors are ptnHydrophilic & hydrophobic ligands
5. Receptor StatesSpecificityMagnitude of responseR (inactive) R *(active)Agonist ???Antagonist ???Partial agonist ???Others
6. Receptor Families
7. Transmembrane ligand-gated ion channels(nicotinic, GABA & ion gated channels)Schematic illustration of ACh receptors
8. Transmembrane G protein-coupled receptorsEC domainIC domain interacts with G ptn or effector moleculeMany kinds of G ptns (Gs, Gi, Gq)All composed of α, β & 𝛾 subunitsThe responses lasts for several seconds to minutes
9. Transmembrane G protein-coupled receptors (cont.)
10.
11. Transmembrane G protein-coupled receptors (cont.)
12. G proteinsPhospholipase CGqIP3DAGGsAdenylyl cyclasecAMPA-B-
13. Enzyme-linked receptors(Insulin Receptors)Dimers or multisubunitsLasts min to hrsEx., epidermal growth factor(EGF), platelet-derived growth factor (PDGF), atrial natriuretic peptide (ANP), insulin & others
14. Intracellular receptorsTakes hours to days to give responseExamples: steroid H, structural pts, Es, RNA & ribosomes
15. Characteristics of Signal Transduction Signal Amplification e.g. albuterol Spare receptors insulin spare Rs = 99% β-adrenoceptors = 5-10%
16. Desensitization, & Down-Regulation of ReceptorsTachyphlaxis: repeated administration of the agonist lead to decrease in responsiveness of Rs Refractory Up-regulation of receptors