Pharmacokinetics and pharmacodynamics Flashcards
(531 cards)
what is pharmacology?
the study of the effects of drugs
what is pharmacokinetics?
how the body affects the drug; Absorption, Distribution, Metabolism and Excretion (ADME)
what is pharmacodynamics?
how the drug affects the body
what is the role of zinc fingers in cytosolic/nuclear receptors?
can recognise discrete regions of DNA
what is potency?
measure of how well a drug works
what is EC50?
concentration (M) that gives half of the maximal response
what is an agonist?
a compound that binds to a receptor and activates it
what are types of normal response curves?
linear (normal scale) and sigmoidal (log scale)
what is a full vs partial agonist?
- full agonist can get a maximal response
- partial agonist cannot get maximal response when binding to receptor
what is Emax?
maximal response of a drug
what is intrinsic activity/efficacy? how is it calculated?
- the relative ability of a drug-receptor complex to produce a maximum functional response
- Emax of partial agonist ÷ Emax of full agonist
what is affinity?
how well a drug binds to a receptor
what is potency?
- a measure of drug activity expressed in terms of the amount required to produce an effect of given intensity
- highly potent drug evokes a given response at low concentrations
- lower potent drug evokes same response only at higher concentrations
what is an antagonist?
- a compound that reduces the effect of an agonist
- does not activate receptors
- affinity of the antagonist for the receptor affects its activity
what is a competitive antagonist? what is its effect on the dose-response curve?
- bind to receptors at same binding site as the endogenous ligand or agonist, but without activating the receptor
- competes for same binding site with agonist
- sufficient concentrations of an antagonist will displace the agonist from the binding sites
- dose-response curve shifts to the right; more agonist is required to elicit the same response; decreased potency
what are the types of competitive antagonists?
- reversible (surmountable)
- irreversible (insurmountable)
what are reversible (surmountable) competitive antagonists?
- bind via noncovalent intermolecular forces
- will eventually dissociate from the receptor, freeing it to be bound again
what are irreversible (insurmountable) competitive antagonists?
- bind via covalent intermolecular forces
- there is not enough free energy to break covalent bones in the local environment, so the bond is essentially permanent, so the complex will never dissociate
- receptor remains permanently antagonised until it is ubiquinated and destroyed
what is a non-competitive antagonist? what effect does it have on the dose-response curve?
- type of insurmountable antagonist that binds to an allosteric (other) site of the receptor, or by irreversibly binding to the active site of the receptor
- reduce maximum response that can be attained by any amount of agonist
- effects cannot be negated, no matter how much agonist is present
- shift right and down of the dose-response curve
what is the agonist and antagonist of the mAChR receptor?
muscarinic ACh receptor
- agonist: muscarine
- antagonist: atropine
what is the agonist and antagonist of the nAChR receptor?
nicotinic ACh receptor
- agonist: nicotine
- antagonist: curare
what is the agonist for the histamine receptor? what are its effects?
agonist: histamine
- contraction of the ileum
- acid secretion from parietal cells
what is the antagonist for the histamine receptor? what are its effects?
antagonist: mepyramine
- reversed contraction of the ileum
- no effect on acid secretion
what is efficacy?
how well a ligand activates the receptor