drug receptor interactions Flashcards
define pharmacokinetics and pharmacodynamics
PK=what the body does to the drug
PD=what the drug does to the body
what is ADME
absorption, distribution, metabolism, elimination
By what medium are most drugs excreted
urine=ary
drugs with a large Vd (volume of distribution) are mostly
in the tissue
if a drug is mostly in the plasma, what Vd does it have?
small
what is a “large” Vd?
compared to a given body weight (volume - 70kg=70l), a few times bigger eg 500 l
what’s the formula for Vd> volume of distribution
amount of drug in the body/drug plasma concentration
what is a small Vd?
<10l
why would a drug stay in the plasma?
binds to albumin or molecule is too big
name some other proteins in teh plasma that drugs can bind to
lipoproteins globulin alpha1-acid glycoproteins
how would you find out how much drug is in left in the body
Vd is known constant, take away how much drug is in the plasma and Bob is your uncle
name 2 drugs with excessive protein binding
diclofenac 99.5% and mefloquine >98%
what drugs bind to albumin
acidic salicylates, frusemide, warfarin, basic drugs
what binds to alpha 1-acid glycoproteins
basic drugs - psychoactive drugs and propranolol
explain why cessation of one drug such as warfarin could have an effect on the efficacy of another drug
polypharmacy - both drugs are extensively bound to a protein. When warfarin is ceased, the other drug suddenly binds to all the receptors, meaning there will be a lot less in the system
what happens to bound drugs
not much. they stay hanging about in the person. not metabolised or excreted
what are the 4 main classes of receptors
GPCR, ligand-gated, kinase-linked and nuclear receptors
what’s the fastest type of receptor
ligand0 gated ion channels
what ligands can bind to ligand-gated ion channels
GABA, aCh, glutamate, 5-HT(seratonin release), ATP
where are there no slit junctions and what’s the implication
BBB, hydrophilic drugs and large molecules can’t get across
how do you get a drug into the brain that can’t cross the BBB. what is this called
inject it into the CSF - intrathecal
how many alpha helices in a ligand gated ion channel and which one opens when the ligand binds
4
2
what happens to a GPCR when a ligand binds
G protein is activated - GDP->GTP. Alpha part dissociates and activates downstream signals such as ion channel mediation
Which receptors are most associated with phosphorylation
protein kinases
