Receptor pharmacology

Receptor pharmacology - BDS, simplified

1. Receptor pharmacology

2. Definition: Receptor : Protein macromolecules on cell surface or cytoplasm Affinity : Capability of drug to bind to receptor Intrinsic activity : Ability of drug to elicit response after binding to receptor

3. Definition: Agonist High affinity and high IA Antagonist High affinity and IA absent Partial agonist High affinity and low IA Inverse agonist Produce effect opposite to agonist

4. Receptor types Ion channel receptor G- protein coupled receptor (Metabotropic) Kinase linked receptor Intra cellular receptors

5. Ion channel receptors Present on cell membrane Coupled to an ion channel Open when receptor occupied by agonist Eg : Benzodiazepine

6. G- protein coupled receptors Receptor bound to effector system through GTP binding protein G protein- α, β , Subunits Effector mechanisms Adenylate cyclase Phospholipase C Ion channel Types- Gs , Gi Eg . Adrenergic drugs

7. Kinase linked receptors Receptor directly linked to tyrosine kinase Autophosphorylation Eg , Insulin

8. Intracellular receptors Located in cytoplasm Alteration in gene transcription Eg : steroid hormone

9. Properties Desentisation After reaching high level response decreases over time Reversible Up regulation Prolonged exposure to high concentration of agonist causes reduction in number of receptors Down regulation Prolonged exposure to high concentration of antagonist causes increase in number of receptors

10. Spare receptors Unoccupied receptors serving as reserve Receptor related diseases Diabetes Myasthenia gravis Familial hypercholesterolemia

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