Pharmacodynamics Flashcards
Dose response curve
-agonist activity can be measured as well as adverse effects of drugs -increasing concentration of agonist results in the biological response to be greater -curve tends to follow a sigmoidal shape
Competitive antagonism
Reduces agonist potency but not efficacy
Allosteric Antagonists
Binds to a different site on the receptor than the endogenous ligand, this affects the receptor function through other conformational effects on the protein
Antagonist
interactions that prevent or block a biological effect
Intracellular receptors
located in cytoplasm bind lipid soluble ligands within the cell i.e.) steroid hormone receptors
Irreversible Antagonists
Binds irreversibly by the same binding site as and endogenous ligand
Partial Agonists
bind SAME site as endogenous ligand but elicit a weaker response, this can decrease the efficacy of the endogenous agonist
LD 50
measures the ED50 at eliciting a lethal effect
Therapeutic Index (TI)
reflects the margin of safety between drug efficacy and adverse effects TI=TD50/ED50
Long term effects of drugs use leads to:
Tolerance and Sensitization
Forms of Tolerance
Metabolic tolerance Pharmacodynamic Tolerance Behavioural tolerance
How do you define a receptor?
it has to be saturable, specific and reversible in binding
Agonist
interactions that elicit a biological effect on receptor
Non-competitive antagonists
cannot be displaced by agonists
Extracellular receptors
localized to cell surface bind water soluble ligands common target for psychoactive drugs i.e.) NTs
Reversible Antagonists
can be displaced by the endogenous agonist
ED50
aka “potency” is the dose required to elicit half maximal effect
Inverse Agonists
Binds receptor with full affinity, has opposite effect to full agonist
TD50
is a measure of the ED50 eliciting a toxic response
Pharmacodynamics
Study of physiological and biochemical interactions with their target tissues and receptors responsible for their ULTIMATE drug effects
