How Drugs Acts: Communication SEM1 Flashcards
Where do drugs come from
Plants
Fungi
Microorganisms
Synthetic chemicals
Biopharmaceuticals
What actions must drugs have
Selective action on a tissue or cell type
What does selective drug action reflect
Reflects specific expression patterns of protein drugs targets
What are the 4 protein targets where mammalian cells usually act by binding to one
Receptors
Ion channels
Enzymes
Carrier molecules (transporters)
Where can the 4 common molecular targets be found (receptors, ion channels, enzymes and carrier molecules)
Anchored in cell membrane
Outside cells - extracellular space
Inside cells - in cytoplasm, intracellular membranes, or nucleus
What is the receptor occupancy determined by a bound ligand
Determined by affinity (ability of drug to bind to receptor)
What equilibrium constant means higher ligand affinity
The smaller the equlibrium constant the higher the affinity of the ligand (e.g KD = 1x10-9 has higher affinity than KD= 1x10-6)
What is KA
KA is the ligand concentration at which 50% of receptors are occupied
How do agonist elicit a functional response
Agonists activate a receptor to elicit a functional response
What does efficacy mean
Given to the term when an agonist has activated and bound to a receptor to elicit an effect
What is the mechanism of competitive, reversible antagonists
competitive, reversible antagonists bind (reversibly) to the agonist binding site but do not activate the receptor
How much efficacy do antagonist have in their purest form
Zero efficacy because it doesn’t activate the receptor
What is irreversible competitive antagonism
Covalent interactions between antagonist and binding site and once bound the antagonist will not dissociate from the receptor
What do allosteric modulators do
Alter the action of agonist by binding to an accessory site on the receptor
What are the underlying mechanisms of local anaesthetics
They block voltage gated Na+ channels preventing action potentials in sensory neurones
