Konorev Pharm Lect Pharmacodynamics Receptors Flashcards
what is an inert binding site?
a component of the biologic system to which a drug binds without changing any function
covalent bonds are reversible or irreversible?
irreversible; in order to get rid of response, must get new receptor made
which of the following processes are studied by pharmacodynamics?
A. metabolism of the drug in the liver
B. excretion of the drug with urine
C. relaxation of bronchial smooth m. by a drug
D. absorption of the drug from the site of administration
C
effect on body
which of the bonds will most likely make binding of the drug to a receptor irreversible?
covalent
what quantitatively describes the relationship between a drug and its effects?
dose-response curve
what is the typical result of the plot of drug dose (x) vs. drug effect (y)?
hyperbolic curve
what is the first portion of the dose-response curve? second?
linear phase; plateau phase
what is a more common presentation of dose-response curve?
logarithmic drug dose, creates sigmoid curve
what is Emax?
maximal effect that is produced by the drug
what is ED50?
(effective dose 50) the dose of a drug that produces 50% of its maximal effect
what does affinity describe?
how readily and tightly a drug binds to a receptor
What is the constant for describing affinity?
Kd
The lower the KD the ___ the affinity?
higher
what is selectivity?
property of a drug determined by its affinities at various binding sites
what does intrinsic activity describe?
the ability of a drug to change a receptor function and produce a physiological response upon its binding to a receptor
what does an agonist do?
binds to receptor and induces a change that produces a physiological response
has intrinsic activity
do antagonists have effect without presence of agonist?
no
what do full agonists do?
fully activate receptors, maximal pharm effect when all receptors are occupied, maximal intrinsic activity
what are inverse agonists?
decrease receptor signaling, decrease response at receptors with a significant level of constitutive receptor activity, intrinsic activity is present and related to the inhibition of receptor function
In the absence of other drugs, Pindolol causes an increase in HR by activating B-AR. In the presence of highly effective B-AR stimulants Pindolol causes a decrease in HR. Therefore, Pindolol should be classified as…?
A partial agonist
– partial agonist replaces where full agonist binds
the effect of an inverse agonist on a receptor activity in the absence of other ligands will be?
inhibition of the baseline receptor activity
what do competitive antagonists compete with?
endogenous chemicals or agonist drugs for binding of the receptor, can be displaced from receptor by other drugs (effects are surmountable)
are binding of non-competitive surmountable?
no
cholestyramine is a bile-acid binding resin that is used for the treatment of hypercholesterolemia. It absorbs aspirin, preventing its absorption in GI tract and antagonizing its effects. What is cholesyramine an example of?
chemical antagonist
Isoproteernol relaxes bronchial smooth m. by activating B-adrenergic receptors while pilocarpine causes contraction of this muscle by stimulating muscarinic receptors. What type of antagonism exists between isoproterenol and pilocarpine?
physiological antagonism
what is a receptor?
a specific molecule in a biological system that plays a REGULATORY ROLE
how do we control adverse effects of a drug?
avoid systemic administration
use highly selective drugs
what does potency describe?
the amount of drug required to produce a specific pharmacological effect
what does efficacy describe?
the maximal pharmacological effect that a drug can produce
related to the total number of receptors available to bind a drug= Bmax
what is a quantal dose response?
binary answer yes or no,
did the pts on drug A lose 10+lbs
what is an example of a graded response?
dose-response curve that depicts the mean amount of weight loss in a group of pts
what is a therapeutic window?
the range of doses of a drug or of its concentration in a bodily system that provides safe and effective therapy
median effective concentration (ED50) in the example below is 0.4 while median toxic (TD50) is 40. The value of therapeutic index (TI) is:
100
