BPS2012 Pharmacology II – Drug Action HD 85 Notes

Summary:

The note titled “BPS2012 Pharmacology II on Drug Action HD 85” summarises key topics in pharmacology. It covers the concepts of agonists and antagonists, the structure and function of G protein-coupled receptors (GPCRs), signal transduction pathways, advanced ligand-receptor interactions, ion channels, enzymes, transporters, nuclear receptors, PKC (protein kinase C), NOS (nitric oxide synthase), receptor tyrosine kinases (RTK), and integrins. These topics encompass a broad range of mechanisms through which drugs interact with targets in the body. By understanding these concepts, pharmacologists can understand how drugs act on specific receptors, modulate signal transduction pathways, affect ion channels and enzymes, interact with transporters, engage nuclear receptors, and impact various cellular processes. This note provides a comprehensive overview of the fundamental aspects of drug action, offering valuable knowledge for studying pharmacology and developing therapeutic interventions.

Excerpt:

BPS2012 Pharmacology II on Drug Action

Agonists
– Receptor occupation / Drug-receptor complex formation
– Note: Ligand = agonist or antagonist
– If the ligand is an agonist, the formation of a ligand-receptor complex initiates a receptor-mediated pharmacological activity
– Law of mass action
– Assumptions:
– Receptors are free or bound
– Ligands can freely access receptors
– Binding is reversible
– Ligand-receptor complex formation does not change either the receptor or li inverse gand (agonist-receptor binding doesn’t change either the receptor or agonist)

BPS2012 Pharmacology II: Drug Action HD 85 notes
Partial agonists
– Both full and partial agonists bind with equal strength to the receptor
– Full and partial agonists elicit different responses
– Partial agonists are weaker activators of signaling, thus regardless of the concentration, they will never produce a maximal response
– 1956, Stephenson suggested a measure of agonist activity = efficacy
– Efficacy = capacity to initiate a response once it occupies a receptor
– Assumptions to elicit an effect, an agonist must:
– Bind to a receptor = affinity
– Activate the receptor = efficacy

BPS2012 Pharmacology II: Drug Action HD 85 notes
Antagonism
Antagonist
– binds to receptors, and stops the receptor from producing the desired
response.
– Affinity, no to little efficacy
– Types
– Physiological antagonism
– When two agonists cancel each other