Pharmacodynamics Flashcards
Describe the term pharmacodynamics
The study of drug action on the body
Describe the term pharmacokinetics
The study of what the body does to the drug
Give 3 examples of protein drug targets
Enzymes
Transporters
Receptors
What are the 4 receptor families?
Ligand-gated ion channel
GPCR’s
Kinase- linked receptor
Nuclear receptor
What is an example a ligand gated ion channel?
Nicotinic Acetylcholine receptor at NMJ
What is an example of a GPCR?
Muscarinic Acetylcholine receptor
What is an example of a kinase-linked receptor?
Cytokine receptors
What is an example of nuclear receptors?
Oestrogen receptor
Define the term Kd
The dissociation constant- a measure of the tendency of the D-R complex to dissociate
What is Fractional Occupancy (pA)?
Concentration at which 50% the available receptors are bound
What is IC50?
Concentration of an inhibitor where the response (binding) is reduced by half
What is EC50?
Effective concentration of drug that gives 50% of max response
What is meant by receptor reserves?
agonist only needs to activate a small fraction of available receptors in order to bring about max response
What is inverse agonsim?
The receptor activation goes below the constitutive level of receptor activation
What 2 factors affect potency?
Efficacy and Affinity
What is the equation for Concentration ratio (schild plot)?
Log(r-1) = Log[B] - LogKb
Kb= Kd of anatgonist
Define the term pA2
The negative log of the concentration of antagonist, that makes it necessary to double the amount of agonist to elicit the same response
What is non-competitive anatgonism?
Antagonist bind to a different site on receptor OR it affects the D-R complex AFTER binding
What is chemical Antagonism?
When 2 substances combine in solution, such tht the effective action of the drug is lost
What is an example of Chemical Antagonsim?
Dimercaprol- used in heavy metal poisonings
How do you calculate Therapeutic Index?
Toxic dose/Effective dose
