Pharmacodynamics- Lectures 12-13 Flashcards
What are agonists?
drugs that produce a response by changing the rate of a biological process form its basal rate; shifts equilibrium towards active state
What is a direct agonist?
a drug that binds directly to the receptor it evokes a response from
What is an indirect agonist?
a drug that increases the level of an endogenous agent
What determines potency?
affinity and intrinsic efficacy; only agonists can be potent
What is a partial agonist?
a drug that is incapable of producing the full response of a system, even when its concentration is sufficient to bind all of the receptors due to its intrinsic efficacy being too low; binds both conformations (active and inactive) so equilibrium achieved between the two states
What is an inverse agonist?
a drug that produces a response, but is in the opposite direction to that of a full or partial agonist; binds/stabilizes to inactive receptor, shifting equilibrium in that direction
How would you calculate the number of receptors bound to drug (B)?
Bmax x [D]
B = ——————–
KD + [D]
How would you calculate the effect of a drug?
Emax x [D]
E = ———————–
EC50 + [D]
What is an antagonist?
a drug that binds to a receptor and does not change their activity, but prevents an agonist from producing a response; binds equally to active and inactive forms so does not change equilibrium
What does it mean if the effect of an antagonist is surmountable?
if its antagonism can be overcome by increasing agonist concentration; if the antagonist shifts the concentration-response curve for the agonist to the R
How would one compare the abilities of different competitive antagonists to inhibit agonist-induced responses?
pA2 = -log(Ka)
What affects population dose-response relationships of drugs?
genetic variations, age, disease, gender, as well as other factors
