What is pharmacodynamics
Studies of the biological and therapeutic effects of drugs
How do drugs act on our body
Drugs act on DNA
Drugs act via a chemical reaction
Drugs act by binding to protein molecules, also called primary drug targets/molecular targets
What are some primary drug targets (protein molecules)
Carrier molecules
Enzymes
Ion channels
Receptors
Carrier molecules (transporters)
Proteins that transport ions or small molecules across the cell membrane e.g. glucose, amino acids or neurotransmitters
Some drugs block the carrier molecule transport system e.g. SSRIs (selective serotonin reuptake inhibitors)
Enzymes
Biological catalysts that carry out countless reactions, have a specific “lock and key analogy”, active site, reversible.
How do drugs act on enzymes
Competitive and non-competitive inhibition
Competitive inhibition
Drug and substrate compete for active site on enzyme, normal reaction is thus slowed down or inhibited. e.g. NSAIDs
Non-competitive inhibition
Drug destroys enzyme and distorts its shape, permanent. e.g. nerve gas
Ion channels
Integral proteins embedded in the cell’s lipid bilayer membrane
Allow ions to move between intracellular and extracellular fluid.
How to drugs act on ion channels
directly linked to a receptor
May help to open or close an ion channel or physically block the ion channel.
Receptors
On cell membranes and in cell’s cytosol
Large group of proteins that are drug targets.
Drug binds to receptors “lock and key analogy” (specific). Bind to receptors as either an agonist or an antagonist.
Agonist
Activate receptors, produces the same response as the endogenous ligand. Potency depends on affinity or efficacy.
Antagonist
Bind to receptors and blocks access of endogenous ligand.
Efficacy = zero.
Types of antagonists
Competitive antagonist
Irreversible antagonist
Non-competitive antagonist.
